Code refactoring for module resolution api (#51675)

* Refactoring so CacheWithRedirects has Key and Value type parameters

* ModuleResolutionCache or TypeRefDirectiveCache will look in directory before solving, so ResolutionCache doesnt need this check

* Test showing module resolution is not shared because resolution cache doesnt update own options

* Enable traceResolution on some of the project reference tests

* Simplify CacheWithRedirects and ensure the options are set in all common scenarios so cache can be shared between redirects

src/compiler/checker.ts

@@ -99,6 +99,7 @@ import {
     createFileDiagnostic,
     createGetCanonicalFileName,
     createGetSymbolWalker,
+    createModeAwareCacheKey,
     createPrinter,
     createPropertyNameNodeForIdentifierOrLiteral,
     createScanner,
@@ -337,8 +338,8 @@ import {
     hasAccessorModifier,
     hasAmbientModifier,
     hasContextSensitiveParameters,
-    hasDecorators,
     HasDecorators,
+    hasDecorators,
     hasDynamicName,
     hasEffectiveModifier,
     hasEffectiveModifiers,
@@ -347,8 +348,8 @@ import {
     hasExtension,
     HasIllegalDecorators,
     HasIllegalModifiers,
-    hasInitializer,
     HasInitializer,
+    hasInitializer,
     hasJSDocNodes,
     hasJSDocParameterTags,
     hasJsonModuleEmitEnabled,
@@ -7406,7 +7407,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             }
             const contextFile = getSourceFileOfNode(getOriginalNode(context.enclosingDeclaration));
             const resolutionMode = overrideImportMode || contextFile?.impliedNodeFormat;
-            const cacheKey = getSpecifierCacheKey(contextFile.path, resolutionMode);
+            const cacheKey = createModeAwareCacheKey(contextFile.path, resolutionMode);
             const links = getSymbolLinks(symbol);
             let specifier = links.specifierCache && links.specifierCache.get(cacheKey);
             if (!specifier) {
@@ -7435,10 +7436,6 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 links.specifierCache.set(cacheKey, specifier);
             }
             return specifier;
-
-            function getSpecifierCacheKey(path: string, mode: ResolutionMode | undefined) {
-                return mode === undefined ? path : `${mode}|${path}`;
-            }
         }
 
         function symbolToEntityNameNode(symbol: Symbol): EntityName {

src/compiler/moduleNameResolver.ts

@@ -5,6 +5,7 @@ import {
     changeAnyExtension,
     CharacterCodes,
     combinePaths,
+    CommandLineOption,
     comparePaths,
     Comparison,
     CompilerOptions,
@@ -35,6 +36,7 @@ import {
     getBaseFileName,
     GetCanonicalFileName,
     getCommonSourceDirectory,
+    getCompilerOptionValue,
     getDirectoryPath,
     GetEffectiveTypeRootsHost,
     getEmitModuleKind,
@@ -66,14 +68,13 @@ import {
     ModuleKind,
     ModuleResolutionHost,
     ModuleResolutionKind,
+    moduleResolutionOptionDeclarations,
     noop,
     noopPush,
     normalizePath,
     normalizeSlashes,
-    optionsHaveModuleResolutionChanges,
     PackageId,
     packageIdToString,
-    ParsedCommandLine,
     Path,
     pathIsRelative,
     Pattern,
@@ -718,58 +719,97 @@ export interface PerModuleNameCache {
     set(directory: string, result: ResolvedModuleWithFailedLookupLocations): void;
 }
 
-/** @internal */
-export interface CacheWithRedirects<T> {
-    getOwnMap: () => Map<string, T>;
-    redirectsMap: Map<Path, Map<string, T>>;
-    getOrCreateMapOfCacheRedirects(redirectedReference: ResolvedProjectReference | undefined): Map<string, T>;
-    clear(): void;
-    setOwnOptions(newOptions: CompilerOptions): void;
-    setOwnMap(newOwnMap: Map<string, T>): void;
+function compilerOptionValueToString(value: unknown): string {
+    if (value === null || typeof value !== "object") { // eslint-disable-line no-null/no-null
+        return "" + value;
+    }
+    if (isArray(value)) {
+        return `[${value.map(e => compilerOptionValueToString(e))?.join(",")}]`;
+    }
+    let str = "{";
+    for (const key in value) {
+        if (hasProperty(value, key)) {
+            str += `${key}: ${compilerOptionValueToString((value as any)[key])}`;
+        }
+    }
+    return str + "}";
 }
 
 /** @internal */
-export function createCacheWithRedirects<T>(options?: CompilerOptions): CacheWithRedirects<T> {
-    let ownMap: Map<string, T> = new Map();
-    const redirectsMap = new Map<Path, Map<string, T>>();
+export function getKeyForCompilerOptions(options: CompilerOptions, affectingOptionDeclarations: readonly CommandLineOption[]) {
+    return affectingOptionDeclarations.map(option => compilerOptionValueToString(getCompilerOptionValue(options, option))).join("|") + (options.pathsBasePath ? `|${options.pathsBasePath}` : undefined);
+}
+
+/** @internal */
+export interface CacheWithRedirects<K, V> {
+    getOrCreateMapOfCacheRedirects(redirectedReference: ResolvedProjectReference | undefined): Map<K, V>;
+    update(newOptions: CompilerOptions): void;
+    clear(): void;
+}
+
+/** @internal */
+export function createCacheWithRedirects<K, V>(ownOptions: CompilerOptions | undefined): CacheWithRedirects<K, V> {
+    type RedirectsCacheKey = string & { __compilerOptionsKey: any; };
+    const redirectsMap = new Map<CompilerOptions, Map<K, V>>();
+    const optionsToRedirectsKey = new Map<CompilerOptions, RedirectsCacheKey>();
+    const redirectsKeyToMap = new Map<RedirectsCacheKey, Map<K, V>>();
+    let ownMap = new Map<K, V>();
+    if (ownOptions) redirectsMap.set(ownOptions, ownMap);
     return {
-        getOwnMap,
-        redirectsMap,
         getOrCreateMapOfCacheRedirects,
+        update,
         clear,
-        setOwnOptions,
-        setOwnMap
     };
 
-    function getOwnMap() {
-        return ownMap;
+    function getOrCreateMapOfCacheRedirects(redirectedReference: ResolvedProjectReference | undefined): Map<K, V> {
+        return redirectedReference ?
+            getOrCreateMap(redirectedReference.commandLine.options) :
+            ownMap;
     }
 
-    function setOwnOptions(newOptions: CompilerOptions) {
-        options = newOptions;
-    }
-
-    function setOwnMap(newOwnMap: Map<string, T>) {
-        ownMap = newOwnMap;
-    }
-
-    function getOrCreateMapOfCacheRedirects(redirectedReference: ResolvedProjectReference | undefined) {
-        if (!redirectedReference) {
-            return ownMap;
+    function update(newOptions: CompilerOptions) {
+        if (ownOptions !== newOptions) {
+            if (ownOptions) ownMap = getOrCreateMap(newOptions); // set new map for new options as ownMap
+            else redirectsMap.set(newOptions, ownMap); // Use existing map if oldOptions = undefined
+            ownOptions = newOptions;
         }
-        const path = redirectedReference.sourceFile.path;
-        let redirects = redirectsMap.get(path);
-        if (!redirects) {
-            // Reuse map if redirected reference map uses same resolution
-            redirects = !options || optionsHaveModuleResolutionChanges(options, redirectedReference.commandLine.options) ? new Map() : ownMap;
-            redirectsMap.set(path, redirects);
+    }
+
+    function getOrCreateMap(redirectOptions: CompilerOptions): Map<K, V> {
+        let result = redirectsMap.get(redirectOptions);
+        if (result) return result;
+        const key = getRedirectsCacheKey(redirectOptions);
+        result = redirectsKeyToMap.get(key);
+        if (!result) {
+            if (ownOptions) {
+                const ownKey = getRedirectsCacheKey(ownOptions);
+                if (ownKey === key) result = ownMap;
+                else if (!redirectsKeyToMap.has(ownKey)) redirectsKeyToMap.set(ownKey, ownMap);
+            }
+            redirectsKeyToMap.set(key, result ??= new Map());
         }
-        return redirects;
+        redirectsMap.set(redirectOptions, result);
+        return result;
     }
 
     function clear() {
+        const ownKey = ownOptions && optionsToRedirectsKey.get(ownOptions);
         ownMap.clear();
         redirectsMap.clear();
+        optionsToRedirectsKey.clear();
+        redirectsKeyToMap.clear();
+        if (ownOptions) {
+            if (ownKey) optionsToRedirectsKey.set(ownOptions, ownKey);
+            redirectsMap.set(ownOptions, ownMap);
+        }
+    }
+
+    function getRedirectsCacheKey(options: CompilerOptions) {
+        let result = optionsToRedirectsKey.get(options);
+        if (!result) {
+            optionsToRedirectsKey.set(options, result = getKeyForCompilerOptions(options, moduleResolutionOptionDeclarations) as RedirectsCacheKey);
+        }
+        return result;
     }
 }
 
@@ -794,7 +834,7 @@ function createPackageJsonInfoCache(currentDirectory: string, getCanonicalFileNa
     }
 }
 
-function getOrCreateCache<T>(cacheWithRedirects: CacheWithRedirects<T>, redirectedReference: ResolvedProjectReference | undefined, key: string, create: () => T): T {
+function getOrCreateCache<K, V>(cacheWithRedirects: CacheWithRedirects<K, V>, redirectedReference: ResolvedProjectReference | undefined, key: K, create: () => V): V {
     const cache = cacheWithRedirects.getOrCreateMapOfCacheRedirects(redirectedReference);
     let result = cache.get(key);
     if (!result) {
@@ -804,35 +844,7 @@ function getOrCreateCache<T>(cacheWithRedirects: CacheWithRedirects<T>, redirect
     return result;
 }
 
-function updateRedirectsMap<T>(
-    options: CompilerOptions,
-    directoryToModuleNameMap: CacheWithRedirects<ModeAwareCache<T>>,
-    moduleNameToDirectoryMap?: CacheWithRedirects<PerModuleNameCache>
-) {
-    if (!options.configFile) return;
-    if (directoryToModuleNameMap.redirectsMap.size === 0) {
-        // The own map will be for projectCompilerOptions
-        Debug.assert(!moduleNameToDirectoryMap || moduleNameToDirectoryMap.redirectsMap.size === 0);
-        Debug.assert(directoryToModuleNameMap.getOwnMap().size === 0);
-        Debug.assert(!moduleNameToDirectoryMap || moduleNameToDirectoryMap.getOwnMap().size === 0);
-        directoryToModuleNameMap.redirectsMap.set(options.configFile.path, directoryToModuleNameMap.getOwnMap());
-        moduleNameToDirectoryMap?.redirectsMap.set(options.configFile.path, moduleNameToDirectoryMap.getOwnMap());
-    }
-    else {
-        // Set correct own map
-        Debug.assert(!moduleNameToDirectoryMap || moduleNameToDirectoryMap.redirectsMap.size > 0);
-        const ref: ResolvedProjectReference = {
-            sourceFile: options.configFile,
-            commandLine: { options } as ParsedCommandLine
-        };
-        directoryToModuleNameMap.setOwnMap(directoryToModuleNameMap.getOrCreateMapOfCacheRedirects(ref));
-        moduleNameToDirectoryMap?.setOwnMap(moduleNameToDirectoryMap.getOrCreateMapOfCacheRedirects(ref));
-    }
-    directoryToModuleNameMap.setOwnOptions(options);
-    moduleNameToDirectoryMap?.setOwnOptions(options);
-}
-
-function createPerDirectoryResolutionCache<T>(currentDirectory: string, getCanonicalFileName: GetCanonicalFileName, directoryToModuleNameMap: CacheWithRedirects<ModeAwareCache<T>>): PerDirectoryResolutionCache<T> {
+function createPerDirectoryResolutionCache<T>(currentDirectory: string, getCanonicalFileName: GetCanonicalFileName, directoryToModuleNameMap: CacheWithRedirects<Path, ModeAwareCache<T>>): PerDirectoryResolutionCache<T> {
     return {
         getOrCreateCacheForDirectory,
         clear,
@@ -844,19 +856,24 @@ function createPerDirectoryResolutionCache<T>(currentDirectory: string, getCanon
     }
 
     function update(options: CompilerOptions) {
-        updateRedirectsMap(options, directoryToModuleNameMap);
+        directoryToModuleNameMap.update(options);
     }
 
     function getOrCreateCacheForDirectory(directoryName: string, redirectedReference?: ResolvedProjectReference) {
         const path = toPath(directoryName, currentDirectory, getCanonicalFileName);
-        return getOrCreateCache<ModeAwareCache<T>>(directoryToModuleNameMap, redirectedReference, path, () => createModeAwareCache());
+        return getOrCreateCache(directoryToModuleNameMap, redirectedReference, path, () => createModeAwareCache());
     }
 }
 
+/** @internal */
+export type ModeAwareCacheKey = string & { __modeAwareCacheKey: any; };
+/** @internal */
+export function createModeAwareCacheKey(specifier: string, mode: ResolutionMode) {
+    return (mode === undefined ? specifier : `${mode}|${specifier}`) as ModeAwareCacheKey;
+}
 /** @internal */
 export function createModeAwareCache<T>(): ModeAwareCache<T> {
     const underlying = new Map<ModeAwareCacheKey, T>();
-    type ModeAwareCacheKey = string & { __modeAwareCacheKey: any; };
     const memoizedReverseKeys = new Map<ModeAwareCacheKey, [specifier: string, mode: ResolutionMode]>();
 
     const cache: ModeAwareCache<T> = {
@@ -887,7 +904,7 @@ export function createModeAwareCache<T>(): ModeAwareCache<T> {
     return cache;
 
     function getUnderlyingCacheKey(specifier: string, mode: ResolutionMode) {
-        const result = (mode === undefined ? specifier : `${mode}|${specifier}`) as ModeAwareCacheKey;
+        const result = createModeAwareCacheKey(specifier, mode);
         memoizedReverseKeys.set(result, [specifier, mode]);
         return result;
     }
@@ -919,24 +936,10 @@ export function createModuleResolutionCache(
     currentDirectory: string,
     getCanonicalFileName: (s: string) => string,
     options?: CompilerOptions
-): ModuleResolutionCache;
-/** @internal */
-export function createModuleResolutionCache(
-    currentDirectory: string,
-    getCanonicalFileName: GetCanonicalFileName,
-    options: undefined,
-    directoryToModuleNameMap: CacheWithRedirects<ModeAwareCache<ResolvedModuleWithFailedLookupLocations>>,
-    moduleNameToDirectoryMap: CacheWithRedirects<PerModuleNameCache>,
-): ModuleResolutionCache;
-export function createModuleResolutionCache(
-    currentDirectory: string,
-    getCanonicalFileName: GetCanonicalFileName,
-    options?: CompilerOptions,
-    directoryToModuleNameMap?: CacheWithRedirects<ModeAwareCache<ResolvedModuleWithFailedLookupLocations>>,
-    moduleNameToDirectoryMap?: CacheWithRedirects<PerModuleNameCache>,
 ): ModuleResolutionCache {
-    const perDirectoryResolutionCache = createPerDirectoryResolutionCache(currentDirectory, getCanonicalFileName, directoryToModuleNameMap ||= createCacheWithRedirects(options));
-    moduleNameToDirectoryMap ||= createCacheWithRedirects(options);
+    const directoryToModuleNameMap = createCacheWithRedirects<Path, ModeAwareCache<ResolvedModuleWithFailedLookupLocations>>(options);
+    const perDirectoryResolutionCache = createPerDirectoryResolutionCache(currentDirectory, getCanonicalFileName, directoryToModuleNameMap);
+    const moduleNameToDirectoryMap = createCacheWithRedirects<ModeAwareCacheKey, PerModuleNameCache>(options);
     const packageJsonInfoCache = createPackageJsonInfoCache(currentDirectory, getCanonicalFileName);
 
     return {
@@ -956,20 +959,21 @@ export function createModuleResolutionCache(
 
     function clearAllExceptPackageJsonInfoCache() {
         perDirectoryResolutionCache.clear();
-        moduleNameToDirectoryMap!.clear();
+        moduleNameToDirectoryMap.clear();
     }
 
     function update(options: CompilerOptions) {
-        updateRedirectsMap(options, directoryToModuleNameMap!, moduleNameToDirectoryMap);
+        directoryToModuleNameMap.update(options);
+        moduleNameToDirectoryMap.update(options);
     }
 
     function getOrCreateCacheForModuleName(nonRelativeModuleName: string, mode: ResolutionMode, redirectedReference?: ResolvedProjectReference): PerModuleNameCache {
         Debug.assert(!isExternalModuleNameRelative(nonRelativeModuleName));
-        return getOrCreateCache(moduleNameToDirectoryMap!, redirectedReference, mode === undefined ? nonRelativeModuleName : `${mode}|${nonRelativeModuleName}`, createPerModuleNameCache);
+        return getOrCreateCache(moduleNameToDirectoryMap, redirectedReference, createModeAwareCacheKey(nonRelativeModuleName, mode), createPerModuleNameCache);
     }
 
     function createPerModuleNameCache(): PerModuleNameCache {
-        const directoryPathMap = new Map<string, ResolvedModuleWithFailedLookupLocations>();
+        const directoryPathMap = new Map<Path, ResolvedModuleWithFailedLookupLocations>();
 
         return { get, set };
 
@@ -1046,23 +1050,9 @@ export function createTypeReferenceDirectiveResolutionCache(
     getCanonicalFileName: (s: string) => string,
     options?: CompilerOptions,
     packageJsonInfoCache?: PackageJsonInfoCache,
-): TypeReferenceDirectiveResolutionCache;
-/** @internal */
-export function createTypeReferenceDirectiveResolutionCache(
-    currentDirectory: string,
-    getCanonicalFileName: GetCanonicalFileName,
-    options: undefined,
-    packageJsonInfoCache: PackageJsonInfoCache | undefined,
-    directoryToModuleNameMap: CacheWithRedirects<ModeAwareCache<ResolvedTypeReferenceDirectiveWithFailedLookupLocations>>,
-): TypeReferenceDirectiveResolutionCache;
-export function createTypeReferenceDirectiveResolutionCache(
-    currentDirectory: string,
-    getCanonicalFileName: GetCanonicalFileName,
-    options?: CompilerOptions,
-    packageJsonInfoCache?: PackageJsonInfoCache | undefined,
-    directoryToModuleNameMap?: CacheWithRedirects<ModeAwareCache<ResolvedTypeReferenceDirectiveWithFailedLookupLocations>>,
 ): TypeReferenceDirectiveResolutionCache {
-    const perDirectoryResolutionCache = createPerDirectoryResolutionCache(currentDirectory, getCanonicalFileName, directoryToModuleNameMap ||= createCacheWithRedirects(options));
+    const directoryToModuleNameMap = createCacheWithRedirects<Path, ModeAwareCache<ResolvedTypeReferenceDirectiveWithFailedLookupLocations>>(options);
+    const perDirectoryResolutionCache = createPerDirectoryResolutionCache(currentDirectory, getCanonicalFileName, directoryToModuleNameMap);
     packageJsonInfoCache ||= createPackageJsonInfoCache(currentDirectory, getCanonicalFileName);
 
     return {

src/compiler/program.ts

@@ -814,17 +814,16 @@ export function loadWithTypeDirectiveCache<T>(names: string[] | readonly FileRef
         return [];
     }
     const resolutions: T[] = [];
-    const cache = new Map<string, T>();
+    const cache = createModeAwareCache<T>();
     for (const name of names) {
         let result: T;
         const mode = getModeForFileReference(name, containingFileMode);
         const strName = getResolutionName(name);
-        const cacheKey = mode !== undefined ? `${mode}|${strName}` : strName;
-        if (cache.has(cacheKey)) {
-            result = cache.get(cacheKey)!;
+        if (cache.has(strName, mode)) {
+            result = cache.get(strName, mode)!;
         }
         else {
-            cache.set(cacheKey, result = loader(strName, containingFile, redirectedReference, mode));
+            cache.set(strName, mode, result = loader(strName, containingFile, redirectedReference, mode));
         }
         resolutions.push(result);
     }
@@ -944,7 +943,7 @@ export function loadWithModeAwareCache<T>(names: readonly StringLiteralLike[] |
         return [];
     }
     const resolutions: T[] = [];
-    const cache = new Map<string, T>();
+    const cache = createModeAwareCache<T>();
     let i = 0;
     for (const entry of resolutionInfo ? resolutionInfo.names : names) {
         let result: T;
@@ -953,12 +952,11 @@ export function loadWithModeAwareCache<T>(names: readonly StringLiteralLike[] |
             getModeForResolutionAtIndex(containingFile, i);
         i++;
         const name = isString(entry) ? entry : entry.text;
-        const cacheKey = mode !== undefined ? `${mode}|${name}` : name;
-        if (cache.has(cacheKey)) {
-            result = cache.get(cacheKey)!;
+        if (cache.has(name, mode)) {
+            result = cache.get(name, mode)!;
         }
         else {
-            cache.set(cacheKey, result = loader(name, mode, containingFileName, redirectedReference));
+            cache.set(name, mode, result = loader(name, mode, containingFileName, redirectedReference));
         }
         resolutions.push(result);
     }

src/compiler/resolutionCache.ts

@@ -2,14 +2,12 @@ import * as ts from "./_namespaces/ts";
 import {
     arrayToMap,
     CachedDirectoryStructureHost,
-    CacheWithRedirects,
     CharacterCodes,
     clearMap,
     closeFileWatcher,
     closeFileWatcherOf,
     CompilerOptions,
     contains,
-    createCacheWithRedirects,
     createModeAwareCache,
     createModuleResolutionCache,
     createMultiMap,
@@ -65,7 +63,6 @@ import {
     parseNodeModuleFromPath,
     Path,
     pathContainsNodeModules,
-    PerModuleNameCache,
     Program,
     removeSuffix,
     removeTrailingDirectorySeparator,
@@ -292,24 +289,18 @@ export function createResolutionCache(resolutionHost: ResolutionCacheHost, rootD
     // The key in the map is source file's path.
     // The values are Map of resolutions with key being name lookedup.
     const resolvedModuleNames = new Map<Path, ModeAwareCache<CachedResolvedModuleWithFailedLookupLocations>>();
-    const perDirectoryResolvedModuleNames: CacheWithRedirects<ModeAwareCache<CachedResolvedModuleWithFailedLookupLocations>> = createCacheWithRedirects();
-    const nonRelativeModuleNameCache: CacheWithRedirects<PerModuleNameCache> = createCacheWithRedirects();
     const moduleResolutionCache = createModuleResolutionCache(
         getCurrentDirectory(),
         resolutionHost.getCanonicalFileName,
-        /*options*/ undefined,
-        perDirectoryResolvedModuleNames,
-        nonRelativeModuleNameCache,
+        resolutionHost.getCompilationSettings(),
     );
 
     const resolvedTypeReferenceDirectives = new Map<Path, ModeAwareCache<CachedResolvedTypeReferenceDirectiveWithFailedLookupLocations>>();
-    const perDirectoryResolvedTypeReferenceDirectives: CacheWithRedirects<ModeAwareCache<CachedResolvedTypeReferenceDirectiveWithFailedLookupLocations>> = createCacheWithRedirects();
     const typeReferenceDirectiveResolutionCache = createTypeReferenceDirectiveResolutionCache(
         getCurrentDirectory(),
         resolutionHost.getCanonicalFileName,
-        /*options*/ undefined,
+        resolutionHost.getCompilationSettings(),
         moduleResolutionCache.getPackageJsonInfoCache(),
-        perDirectoryResolvedTypeReferenceDirectives
     );
 
     /**
@@ -387,6 +378,8 @@ export function createResolutionCache(resolutionHost: ResolutionCacheHost, rootD
         affectingPathChecksForFile = undefined;
         moduleResolutionCache.clear();
         typeReferenceDirectiveResolutionCache.clear();
+        moduleResolutionCache.update(resolutionHost.getCompilationSettings());
+        typeReferenceDirectiveResolutionCache.update(resolutionHost.getCompilationSettings());
         impliedFormatPackageJsons.clear();
         hasChangedAutomaticTypeDirectiveNames = false;
     }
@@ -514,8 +507,7 @@ export function createResolutionCache(resolutionHost: ResolutionCacheHost, rootD
         names: readonly string[] | readonly FileReference[];
         containingFile: string;
         redirectedReference: ResolvedProjectReference | undefined;
-        cache: Map<Path, ModeAwareCache<T>>;
-        perDirectoryCacheWithRedirects: CacheWithRedirects<ModeAwareCache<T>>;
+        perFileCache: Map<Path, ModeAwareCache<T>>;
         loader: (name: string, containingFile: string, options: CompilerOptions, host: ModuleResolutionHost, redirectedReference?: ResolvedProjectReference, containingSourceFile?: SourceFile, resolutionMode?: ResolutionMode) => T;
         getResolutionWithResolvedFileName: GetResolutionWithResolvedFileName<T, R>;
         shouldRetryResolution: (t: T) => boolean;
@@ -527,19 +519,12 @@ export function createResolutionCache(resolutionHost: ResolutionCacheHost, rootD
     }
     function resolveNamesWithLocalCache<T extends ResolutionWithFailedLookupLocations, R extends ResolutionWithResolvedFileName>({
         names, containingFile, redirectedReference,
-        cache, perDirectoryCacheWithRedirects,
+        perFileCache,
         loader, getResolutionWithResolvedFileName,
         shouldRetryResolution, reusedNames, resolutionInfo, logChanges, containingSourceFile, containingSourceFileMode
     }: ResolveNamesWithLocalCacheInput<T, R>): (R | undefined)[] {
         const path = resolutionHost.toPath(containingFile);
-        const resolutionsInFile = cache.get(path) || cache.set(path, createModeAwareCache()).get(path)!;
-        const dirPath = getDirectoryPath(path);
-        const perDirectoryCache = perDirectoryCacheWithRedirects.getOrCreateMapOfCacheRedirects(redirectedReference);
-        let perDirectoryResolution = perDirectoryCache.get(dirPath);
-        if (!perDirectoryResolution) {
-            perDirectoryResolution = createModeAwareCache();
-            perDirectoryCache.set(dirPath, perDirectoryResolution);
-        }
+        const resolutionsInFile = perFileCache.get(path) || perFileCache.set(path, createModeAwareCache()).get(path)!;
         const resolvedModules: (R | undefined)[] = [];
         const compilerOptions = resolutionHost.getCompilationSettings();
         const hasInvalidatedNonRelativeUnresolvedImport = logChanges && isFileWithInvalidatedNonRelativeUnresolvedImports(path);
@@ -575,39 +560,9 @@ export function createResolutionCache(resolutionHost: ResolutionCacheHost, rootD
                 // If the name is unresolved import that was invalidated, recalculate
                 (hasInvalidatedNonRelativeUnresolvedImport && !isExternalModuleNameRelative(name) && shouldRetryResolution(resolution))) {
                 const existingResolution = resolution;
-                const resolutionInDirectory = perDirectoryResolution.get(name, mode);
-                if (resolutionInDirectory) {
-                    resolution = resolutionInDirectory;
-                    const host = resolutionHost.getCompilerHost?.() || resolutionHost;
-                    if (isTraceEnabled(compilerOptions, host)) {
-                        const resolved = getResolutionWithResolvedFileName(resolution);
-                        trace(
-                            host,
-                            loader === resolveModuleName as unknown ?
-                                resolved?.resolvedFileName ?
-                                    resolved.packageId ?
-                                        Diagnostics.Reusing_resolution_of_module_0_from_1_found_in_cache_from_location_2_it_was_successfully_resolved_to_3_with_Package_ID_4 :
-                                        Diagnostics.Reusing_resolution_of_module_0_from_1_found_in_cache_from_location_2_it_was_successfully_resolved_to_3 :
-                                    Diagnostics.Reusing_resolution_of_module_0_from_1_found_in_cache_from_location_2_it_was_not_resolved :
-                                resolved?.resolvedFileName ?
-                                    resolved.packageId ?
-                                        Diagnostics.Reusing_resolution_of_type_reference_directive_0_from_1_found_in_cache_from_location_2_it_was_successfully_resolved_to_3_with_Package_ID_4 :
-                                        Diagnostics.Reusing_resolution_of_type_reference_directive_0_from_1_found_in_cache_from_location_2_it_was_successfully_resolved_to_3 :
-                                    Diagnostics.Reusing_resolution_of_type_reference_directive_0_from_1_found_in_cache_from_location_2_it_was_not_resolved,
-                            name,
-                            containingFile,
-                            getDirectoryPath(containingFile),
-                            resolved?.resolvedFileName,
-                            resolved?.packageId && packageIdToString(resolved.packageId)
-                        );
-                    }
-                }
-                else {
-                    resolution = loader(name, containingFile, compilerOptions, resolutionHost.getCompilerHost?.() || resolutionHost, redirectedReference, containingSourceFile, mode);
-                    perDirectoryResolution.set(name, mode, resolution);
-                    if (resolutionHost.onDiscoveredSymlink && resolutionIsSymlink(resolution)) {
-                        resolutionHost.onDiscoveredSymlink();
-                    }
+                resolution = loader(name, containingFile, compilerOptions, resolutionHost.getCompilerHost?.() || resolutionHost, redirectedReference, containingSourceFile, mode);
+                if (resolutionHost.onDiscoveredSymlink && resolutionIsSymlink(resolution)) {
+                    resolutionHost.onDiscoveredSymlink();
                 }
                 resolutionsInFile.set(name, mode, resolution);
                 watchFailedLookupLocationsOfExternalModuleResolutions(name, resolution, path, getResolutionWithResolvedFileName);
@@ -703,8 +658,7 @@ export function createResolutionCache(resolutionHost: ResolutionCacheHost, rootD
             names: typeDirectiveNames,
             containingFile,
             redirectedReference,
-            cache: resolvedTypeReferenceDirectives,
-            perDirectoryCacheWithRedirects: perDirectoryResolvedTypeReferenceDirectives,
+            perFileCache: resolvedTypeReferenceDirectives,
             loader: resolveTypeReferenceDirective,
             getResolutionWithResolvedFileName: getResolvedTypeReferenceDirective,
             shouldRetryResolution: resolution => resolution.resolvedTypeReferenceDirective === undefined,
@@ -725,8 +679,7 @@ export function createResolutionCache(resolutionHost: ResolutionCacheHost, rootD
             names: moduleNames,
             containingFile,
             redirectedReference,
-            cache: resolvedModuleNames,
-            perDirectoryCacheWithRedirects: perDirectoryResolvedModuleNames,
+            perFileCache: resolvedModuleNames,
             loader: resolveModuleName,
             getResolutionWithResolvedFileName: getResolvedModule,
             shouldRetryResolution: resolution => !resolution.resolvedModule || !resolutionExtensionIsTSOrJson(resolution.resolvedModule.extension),

src/compiler/types.ts

@@ -4,6 +4,7 @@ import {
     EmitHelperFactory,
     MapLike,
     ModeAwareCache,
+    ModeAwareCacheKey,
     ModuleResolutionCache,
     MultiMap,
     NodeFactoryFlags,
@@ -5503,7 +5504,7 @@ export interface SymbolLinks {
     enumKind?: EnumKind;                        // Enum declaration classification
     originatingImport?: ImportDeclaration | ImportCall; // Import declaration which produced the symbol, present if the symbol is marked as uncallable but had call signatures in `resolveESModuleSymbol`
     lateSymbol?: Symbol;                        // Late-bound symbol for a computed property
-    specifierCache?: Map<string, string>;     // For symbols corresponding to external modules, a cache of incoming path -> module specifier name mappings
+    specifierCache?: Map<ModeAwareCacheKey, string>; // For symbols corresponding to external modules, a cache of incoming path -> module specifier name mappings
     extendedContainers?: Symbol[];              // Containers (other than the parent) which this symbol is aliased in
     extendedContainersByFile?: Map<NodeId, Symbol[]>; // Containers (other than the parent) which this symbol is aliased in
     variances?: VarianceFlags[];                // Alias symbol type argument variance cache

src/services/documentRegistry.ts

@@ -8,17 +8,14 @@ import {
     ensureScriptKind,
     firstDefinedIterator,
     forEachEntry,
-    getCompilerOptionValue,
     getEmitScriptTarget,
     getImpliedNodeFormatForFile,
+    getKeyForCompilerOptions,
     getOrUpdate,
     getSetExternalModuleIndicator,
-    hasProperty,
     identity,
-    isArray,
     IScriptSnapshot,
     isDeclarationFileName,
-    map,
     MinimalResolutionCacheHost,
     Path,
     ResolutionMode,
@@ -407,24 +404,8 @@ export function createDocumentRegistryInternal(useCaseSensitiveFileNames?: boole
     };
 }
 
-function compilerOptionValueToString(value: unknown): string {
-    if (value === null || typeof value !== "object") { // eslint-disable-line no-null/no-null
-        return "" + value;
-    }
-    if (isArray(value)) {
-        return `[${map(value, e => compilerOptionValueToString(e))?.join(",")}]`;
-    }
-    let str = "{";
-    for (const key in value) {
-        if (hasProperty(value, key)) {
-            str += `${key}: ${compilerOptionValueToString((value as any)[key])}`;
-        }
-    }
-    return str + "}";
-}
-
 function getKeyForCompilationSettings(settings: CompilerOptions): DocumentRegistryBucketKey {
-    return sourceFileAffectingCompilerOptions.map(option => compilerOptionValueToString(getCompilerOptionValue(settings, option))).join("|") + (settings.pathsBasePath ? `|${settings.pathsBasePath}` : undefined) as DocumentRegistryBucketKey;
+    return getKeyForCompilerOptions(settings, sourceFileAffectingCompilerOptions) as DocumentRegistryBucketKey;
 }
 
 function getDocumentRegistryBucketKeyWithMode(key: DocumentRegistryBucketKey, mode: ResolutionMode) {

src/testRunner/unittests/tscWatch/projectsWithReferences.ts

@@ -30,7 +30,7 @@ describe("unittests:: tsc-watch:: projects with references: invoking when refere
             ],
             { currentDirectory: `/user/username/projects/sample1` }
         ),
-        commandLineArgs: ["-w", "-p", "tests"],
+        commandLineArgs: ["-w", "-p", "tests", "--traceResolution", "--explainFiles"],
         changes: [
             {
                 caption: "local edit in logic ts, and build logic",
@@ -91,7 +91,7 @@ describe("unittests:: tsc-watch:: projects with references: invoking when refere
             ],
             { currentDirectory: `/user/username/projects/transitiveReferences` }
         ),
-        commandLineArgs: ["-w", "-p", "tsconfig.c.json"],
+        commandLineArgs: ["-w", "-p", "tsconfig.c.json", "--traceResolution", "--explainFiles"],
         changes: [
             {
                 caption: "non local edit b ts, and build b",
@@ -179,7 +179,7 @@ describe("unittests:: tsc-watch:: projects with references: invoking when refere
             ],
             { currentDirectory: `/user/username/projects/transitiveReferences` }
         ),
-        commandLineArgs: ["-w", "-p", "tsconfig.c.json"],
+        commandLineArgs: ["-w", "-p", "tsconfig.c.json", "--traceResolution", "--explainFiles"],
         changes: ts.emptyArray,
         baselineDependencies: true,
     });
@@ -234,7 +234,7 @@ X;`,
             ],
             { currentDirectory: `/user/username/projects/transitiveReferences` }
         ),
-        commandLineArgs: ["-w", "-p", "c"],
+        commandLineArgs: ["-w", "-p", "c", "--traceResolution", "--explainFiles"],
         changes: [
             {
                 caption: "non local edit b ts, and build b",
@@ -353,7 +353,7 @@ X;`,
             ],
             { currentDirectory: `/user/username/projects/transitiveReferences` }
         ),
-        commandLineArgs: ["-w", "-p", "c"],
+        commandLineArgs: ["-w", "-p", "c", "--traceResolution", "--explainFiles"],
         changes: [
             {
                 caption: "non local edit b ts, and build b",
@@ -439,7 +439,7 @@ X;`,
             ],
             { currentDirectory: `/user/username/projects/sample1` }
         ),
-        commandLineArgs: ["-w", "-p", "logic"],
+        commandLineArgs: ["-w", "-p", "logic", "--traceResolution", "--explainFiles"],
         changes: [
             {
                 caption: "change declration map in core",

src/testRunner/unittests/tsserver/resolutionCache.ts

@@ -1,10 +1,14 @@
 import * as ts from "../../_namespaces/ts";
+import * as Utils from "../../_namespaces/Utils";
 import {
     createServerHost,
     File,
     libFile,
     TestServerHost,
 } from "../virtualFileSystemWithWatch";
+import {
+    compilerOptionsToConfigJson,
+} from "../tsc/helpers";
 import {
     baselineTsserverLogs,
     checkNumberOfProjects,
@@ -630,3 +634,73 @@ export const x = 10;`
         });
     });
 });
+
+describe("unittests:: tsserver:: resolutionCache:: tsserverProjectSystem with project references", () => {
+    it("sharing across references", () => {
+        const host = createServerHost({
+            "/src/projects/node_modules/moduleX/index.d.ts": "export const x = 10;",
+            "/src/projects/common/tsconfig.json": JSON.stringify({
+                compilerOptions: compilerOptionsToConfigJson({
+                    composite: true,
+                    traceResolution: true,
+                }),
+            }),
+            "/src/projects/common/moduleA.ts": "export const a = 10;",
+            "/src/projects/common/moduleB.ts": Utils.dedent`
+                import { x } from "moduleX";
+                export const b = x;
+            `,
+            "/src/projects/app/tsconfig.json": JSON.stringify({
+                compilerOptions: compilerOptionsToConfigJson({
+                    composite: true,
+                    traceResolution: true,
+                }),
+                references: [{ path: "../common" }],
+            }),
+            "/src/projects/app/appA.ts": Utils.dedent`
+                import { x } from "moduleX";
+                export const y = x;
+            `,
+            "/src/projects/app/appB.ts": Utils.dedent`
+                import { x } from "../common/moduleB";
+                export const y = x;
+            `,
+        });
+        const session = createSession(host, { logger: createLoggerWithInMemoryLogs(host) });
+        openFilesForSession(["/src/projects/app/appB.ts"], session);
+        baselineTsserverLogs("resolutionCache", "sharing across references", session);
+    });
+
+    it("not sharing across references", () => {
+        const host = createServerHost({
+            "/src/projects/node_modules/moduleX/index.d.ts": "export const x = 10;",
+            "/src/projects/common/tsconfig.json": JSON.stringify({
+                compilerOptions: { composite: true, traceResolution: true },
+            }),
+            "/src/projects/common/moduleA.ts": "export const a = 10;",
+            "/src/projects/common/moduleB.ts": Utils.dedent`
+                import { x } from "moduleX";
+                export const b = x;
+            `,
+            "/src/projects/app/tsconfig.json": JSON.stringify({
+                compilerOptions: {
+                    composite: true,
+                    traceResolution: true,
+                    typeRoots: [], // Just some sample option that is different across the projects
+                },
+                references: [{ path: "../common" }],
+            }),
+            "/src/projects/app/appA.ts": Utils.dedent`
+                import { x } from "moduleX";
+                export const y = x;
+            `,
+            "/src/projects/app/appB.ts": Utils.dedent`
+                import { x } from "../common/moduleB";
+                export const y = x;
+            `,
+        });
+        const session = createSession(host, { logger: createLoggerWithInMemoryLogs(host) });
+        openFilesForSession(["/src/projects/app/appB.ts"], session);
+        baselineTsserverLogs("resolutionCache", "not sharing across references", session);
+    });
+});

tests/baselines/reference/tscWatch/projectsWithReferences/on-sample-project.js

@@ -395,17 +395,50 @@ export declare const m: typeof mod;
 }
 
 
-/a/lib/tsc.js -w -p tests
+/a/lib/tsc.js -w -p tests --traceResolution --explainFiles
 Output::
 >> Screen clear
 [12:01:16 AM] Starting compilation in watch mode...
 
+======== Resolving module '../core/index' from '/user/username/projects/sample1/tests/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/sample1/core/index', target file types: TypeScript, Declaration.
+File '/user/username/projects/sample1/core/index.ts' exist - use it as a name resolution result.
+======== Module name '../core/index' was successfully resolved to '/user/username/projects/sample1/core/index.ts'. ========
+======== Resolving module '../logic/index' from '/user/username/projects/sample1/tests/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/sample1/logic/index', target file types: TypeScript, Declaration.
+File '/user/username/projects/sample1/logic/index.ts' exist - use it as a name resolution result.
+======== Module name '../logic/index' was successfully resolved to '/user/username/projects/sample1/logic/index.ts'. ========
+======== Resolving module '../core/anotherModule' from '/user/username/projects/sample1/tests/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/sample1/core/anotherModule', target file types: TypeScript, Declaration.
+File '/user/username/projects/sample1/core/anotherModule.ts' exist - use it as a name resolution result.
+======== Module name '../core/anotherModule' was successfully resolved to '/user/username/projects/sample1/core/anotherModule.ts'. ========
+======== Resolving module '../core/anotherModule' from '/user/username/projects/sample1/logic/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/sample1/logic/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '../core/anotherModule' was successfully resolved to '/user/username/projects/sample1/core/anotherModule.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+core/index.d.ts
+  Imported via '../core/index' from file 'tests/index.ts'
+  File is output of project reference source 'core/index.ts'
+core/anotherModule.d.ts
+  Imported via '../core/anotherModule' from file 'logic/index.d.ts'
+  Imported via '../core/anotherModule' from file 'tests/index.ts'
+  File is output of project reference source 'core/anotherModule.ts'
+logic/index.d.ts
+  Imported via '../logic/index' from file 'tests/index.ts'
+  File is output of project reference source 'logic/index.ts'
+tests/index.ts
+  Part of 'files' list in tsconfig.json
 [12:01:17 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/sample1/tests/index.ts"]
-Program options: {"composite":true,"declaration":true,"forceConsistentCasingInFileNames":true,"skipDefaultLibCheck":true,"watch":true,"project":"/user/username/projects/sample1/tests","configFilePath":"/user/username/projects/sample1/tests/tsconfig.json"}
+Program options: {"composite":true,"declaration":true,"forceConsistentCasingInFileNames":true,"skipDefaultLibCheck":true,"watch":true,"project":"/user/username/projects/sample1/tests","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/sample1/tests/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -733,12 +766,27 @@ Output::
 >> Screen clear
 [12:01:51 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../core/anotherModule' from '/user/username/projects/sample1/logic/index.ts' of old program, it was successfully resolved to '/user/username/projects/sample1/core/anotherModule.ts'.
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+core/index.d.ts
+  Imported via '../core/index' from file 'tests/index.ts'
+  File is output of project reference source 'core/index.ts'
+core/anotherModule.d.ts
+  Imported via '../core/anotherModule' from file 'logic/index.d.ts'
+  Imported via '../core/anotherModule' from file 'tests/index.ts'
+  File is output of project reference source 'core/anotherModule.ts'
+logic/index.d.ts
+  Imported via '../logic/index' from file 'tests/index.ts'
+  File is output of project reference source 'logic/index.ts'
+tests/index.ts
+  Part of 'files' list in tsconfig.json
 [12:01:58 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/sample1/tests/index.ts"]
-Program options: {"composite":true,"declaration":true,"forceConsistentCasingInFileNames":true,"skipDefaultLibCheck":true,"watch":true,"project":"/user/username/projects/sample1/tests","configFilePath":"/user/username/projects/sample1/tests/tsconfig.json"}
+Program options: {"composite":true,"declaration":true,"forceConsistentCasingInFileNames":true,"skipDefaultLibCheck":true,"watch":true,"project":"/user/username/projects/sample1/tests","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/sample1/tests/tsconfig.json"}
 Program structureReused: Completely
 Program files::
 /a/lib/lib.d.ts
@@ -1009,12 +1057,33 @@ Output::
 >> Screen clear
 [12:02:20 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../core/index' from '/user/username/projects/sample1/tests/index.ts' of old program, it was successfully resolved to '/user/username/projects/sample1/core/index.ts'.
+Reusing resolution of module '../logic/index' from '/user/username/projects/sample1/tests/index.ts' of old program, it was successfully resolved to '/user/username/projects/sample1/logic/index.ts'.
+Reusing resolution of module '../core/anotherModule' from '/user/username/projects/sample1/tests/index.ts' of old program, it was successfully resolved to '/user/username/projects/sample1/core/anotherModule.ts'.
+======== Resolving module '../core/anotherModule' from '/user/username/projects/sample1/logic/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/sample1/logic/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '../core/anotherModule' was successfully resolved to '/user/username/projects/sample1/core/anotherModule.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+core/index.d.ts
+  Imported via '../core/index' from file 'tests/index.ts'
+  File is output of project reference source 'core/index.ts'
+core/anotherModule.d.ts
+  Imported via '../core/anotherModule' from file 'logic/decls/index.d.ts'
+  Imported via '../core/anotherModule' from file 'tests/index.ts'
+  File is output of project reference source 'core/anotherModule.ts'
+logic/decls/index.d.ts
+  Imported via '../logic/index' from file 'tests/index.ts'
+  File is output of project reference source 'logic/index.ts'
+tests/index.ts
+  Part of 'files' list in tsconfig.json
 [12:02:27 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/sample1/tests/index.ts"]
-Program options: {"composite":true,"declaration":true,"forceConsistentCasingInFileNames":true,"skipDefaultLibCheck":true,"watch":true,"project":"/user/username/projects/sample1/tests","configFilePath":"/user/username/projects/sample1/tests/tsconfig.json"}
+Program options: {"composite":true,"declaration":true,"forceConsistentCasingInFileNames":true,"skipDefaultLibCheck":true,"watch":true,"project":"/user/username/projects/sample1/tests","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/sample1/tests/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts

tests/baselines/reference/tscWatch/projectsWithReferences/on-transitive-references-in-different-folders-with-no-files-clause.js

@@ -186,17 +186,53 @@ a_1.X;
 
 
 
-/a/lib/tsc.js -w -p c
+/a/lib/tsc.js -w -p c --traceResolution --explainFiles
 Output::
 >> Screen clear
 [12:00:59 AM] Starting compilation in watch mode...
 
+======== Resolving module '../b' from '/user/username/projects/transitiveReferences/c/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/b', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/b.ts' does not exist.
+File '/user/username/projects/transitiveReferences/b.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/b.d.ts' does not exist.
+File '/user/username/projects/transitiveReferences/b/package.json' does not exist.
+File '/user/username/projects/transitiveReferences/b/index.ts' exist - use it as a name resolution result.
+======== Module name '../b' was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences/c', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution '../refs/*', candidate module location: '../refs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/refs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/refs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/b/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  File is output of project reference source 'a/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Matched by default include pattern '**/*'
 [12:01:03 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -370,12 +406,25 @@ Output::
 >> Screen clear
 [12:01:19 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'.
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  File is output of project reference source 'a/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Matched by default include pattern '**/*'
 [12:01:23 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Completely
 Program files::
 /a/lib/lib.d.ts
@@ -468,12 +517,48 @@ Output::
 >> Screen clear
 [12:01:31 AM] File change detected. Starting incremental compilation...
 
+======== Resolving module '../b' from '/user/username/projects/transitiveReferences/c/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/b', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/b.ts' does not exist.
+File '/user/username/projects/transitiveReferences/b.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/b.d.ts' does not exist.
+File '/user/username/projects/transitiveReferences/b/package.json' does not exist.
+File '/user/username/projects/transitiveReferences/b/index.ts' exist - use it as a name resolution result.
+======== Module name '../b' was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences/c', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution '../nrefs/*', candidate module location: '../nrefs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/nrefs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/nrefs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/nrefs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/nrefs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/nrefs/a.d.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/b/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  File is output of project reference source 'a/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+nrefs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Matched by default include pattern '**/*'
 [12:01:35 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../nrefs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../nrefs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -561,12 +646,48 @@ Output::
 >> Screen clear
 [12:01:39 AM] File change detected. Starting incremental compilation...
 
+======== Resolving module '../b' from '/user/username/projects/transitiveReferences/c/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/b', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/b.ts' does not exist.
+File '/user/username/projects/transitiveReferences/b.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/b.d.ts' does not exist.
+File '/user/username/projects/transitiveReferences/b/package.json' does not exist.
+File '/user/username/projects/transitiveReferences/b/index.ts' exist - use it as a name resolution result.
+======== Module name '../b' was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences/c', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution '../refs/*', candidate module location: '../refs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/refs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/refs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/b/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  File is output of project reference source 'a/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Matched by default include pattern '**/*'
 [12:01:43 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -654,12 +775,29 @@ Output::
 >> Screen clear
 [12:01:47 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../b' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/b/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/nrefs/a.d.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+nrefs/a.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Matched by default include pattern '**/*'
 [12:01:48 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -748,12 +886,28 @@ Output::
 >> Screen clear
 [12:01:53 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../b' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/b/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+refs/a.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  Imported via "@ref/a" from file 'c/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+c/index.ts
+  Matched by default include pattern '**/*'
 [12:01:54 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -829,17 +983,39 @@ Output::
 >> Screen clear
 [12:01:56 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../b' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences/c', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution '../refs/*', candidate module location: '../refs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/refs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/refs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
 c/tsconfig.json:1:84 - error TS6053: File '/user/username/projects/transitiveReferences/b' not found.
 
 1 {"compilerOptions":{"baseUrl":"./","paths":{"@ref/*":["../refs/*"]}},"references":[{"path":"../b"}]}
                                                                                      ~~~~~~~~~~~~~~~
 
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+refs/a.d.ts
+  Imported via '@ref/a' from file 'b/index.ts'
+  Imported via "@ref/a" from file 'c/index.ts'
+b/index.ts
+  Imported via '../b' from file 'c/index.ts'
+c/index.ts
+  Matched by default include pattern '**/*'
 [12:02:03 AM] Found 1 error. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -917,12 +1093,30 @@ Output::
 >> Screen clear
 [12:02:06 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../b' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/b/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  File is output of project reference source 'a/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Matched by default include pattern '**/*'
 [12:02:10 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -1010,17 +1204,31 @@ Output::
 >> Screen clear
 [12:02:12 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../b' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'.
 b/tsconfig.json:1:96 - error TS6053: File '/user/username/projects/transitiveReferences/a' not found.
 
 1 {"compilerOptions":{"composite":true,"baseUrl":"./","paths":{"@ref/*":["../*"]}},"references":[{"path":"../a"}]}
                                                                                                  ~~~~~~~~~~~~~~~
 
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Matched by default include pattern '**/*'
 [12:02:16 AM] Found 1 error. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -1108,12 +1316,27 @@ Output::
 >> Screen clear
 [12:02:20 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../b' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'.
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  File is output of project reference source 'a/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Matched by default include pattern '**/*'
 [12:02:21 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts

tests/baselines/reference/tscWatch/projectsWithReferences/on-transitive-references-in-different-folders.js

@@ -186,17 +186,53 @@ a_1.X;
 
 
 
-/a/lib/tsc.js -w -p c
+/a/lib/tsc.js -w -p c --traceResolution --explainFiles
 Output::
 >> Screen clear
 [12:00:59 AM] Starting compilation in watch mode...
 
+======== Resolving module '../b' from '/user/username/projects/transitiveReferences/c/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/b', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/b.ts' does not exist.
+File '/user/username/projects/transitiveReferences/b.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/b.d.ts' does not exist.
+File '/user/username/projects/transitiveReferences/b/package.json' does not exist.
+File '/user/username/projects/transitiveReferences/b/index.ts' exist - use it as a name resolution result.
+======== Module name '../b' was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences/c', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution '../refs/*', candidate module location: '../refs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/refs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/refs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/b/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  File is output of project reference source 'a/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Part of 'files' list in tsconfig.json
 [12:01:03 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -368,12 +404,25 @@ Output::
 >> Screen clear
 [12:01:19 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'.
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  File is output of project reference source 'a/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Part of 'files' list in tsconfig.json
 [12:01:23 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Completely
 Program files::
 /a/lib/lib.d.ts
@@ -464,12 +513,48 @@ Output::
 >> Screen clear
 [12:01:31 AM] File change detected. Starting incremental compilation...
 
+======== Resolving module '../b' from '/user/username/projects/transitiveReferences/c/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/b', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/b.ts' does not exist.
+File '/user/username/projects/transitiveReferences/b.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/b.d.ts' does not exist.
+File '/user/username/projects/transitiveReferences/b/package.json' does not exist.
+File '/user/username/projects/transitiveReferences/b/index.ts' exist - use it as a name resolution result.
+======== Module name '../b' was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences/c', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution '../nrefs/*', candidate module location: '../nrefs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/nrefs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/nrefs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/nrefs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/nrefs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/nrefs/a.d.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/b/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  File is output of project reference source 'a/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+nrefs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Part of 'files' list in tsconfig.json
 [12:01:35 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../nrefs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../nrefs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -555,12 +640,48 @@ Output::
 >> Screen clear
 [12:01:39 AM] File change detected. Starting incremental compilation...
 
+======== Resolving module '../b' from '/user/username/projects/transitiveReferences/c/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/b', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/b.ts' does not exist.
+File '/user/username/projects/transitiveReferences/b.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/b.d.ts' does not exist.
+File '/user/username/projects/transitiveReferences/b/package.json' does not exist.
+File '/user/username/projects/transitiveReferences/b/index.ts' exist - use it as a name resolution result.
+======== Module name '../b' was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences/c', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution '../refs/*', candidate module location: '../refs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/refs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/refs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/b/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  File is output of project reference source 'a/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Part of 'files' list in tsconfig.json
 [12:01:43 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -646,12 +767,29 @@ Output::
 >> Screen clear
 [12:01:47 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../b' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/b/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/nrefs/a.d.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+nrefs/a.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Part of 'files' list in tsconfig.json
 [12:01:48 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -736,12 +874,28 @@ Output::
 >> Screen clear
 [12:01:53 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../b' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/b/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+refs/a.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  Imported via "@ref/a" from file 'c/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+c/index.ts
+  Part of 'files' list in tsconfig.json
 [12:01:54 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -813,17 +967,39 @@ Output::
 >> Screen clear
 [12:01:56 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../b' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences/c', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution '../refs/*', candidate module location: '../refs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/refs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/refs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
 c/tsconfig.json:1:105 - error TS6053: File '/user/username/projects/transitiveReferences/b' not found.
 
 1 {"compilerOptions":{"baseUrl":"./","paths":{"@ref/*":["../refs/*"]}},"files":["index.ts"],"references":[{"path":"../b"}]}
                                                                                                           ~~~~~~~~~~~~~~~
 
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+refs/a.d.ts
+  Imported via '@ref/a' from file 'b/index.ts'
+  Imported via "@ref/a" from file 'c/index.ts'
+b/index.ts
+  Imported via '../b' from file 'c/index.ts'
+c/index.ts
+  Part of 'files' list in tsconfig.json
 [12:02:03 AM] Found 1 error. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -899,12 +1075,30 @@ Output::
 >> Screen clear
 [12:02:06 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../b' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/b/tsconfig.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  File is output of project reference source 'a/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Part of 'files' list in tsconfig.json
 [12:02:10 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -990,17 +1184,31 @@ Output::
 >> Screen clear
 [12:02:12 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../b' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'.
 b/tsconfig.json:1:117 - error TS6053: File '/user/username/projects/transitiveReferences/a' not found.
 
 1 {"compilerOptions":{"composite":true,"baseUrl":"./","paths":{"@ref/*":["../*"]}},"files":["index.ts"],"references":[{"path":"../a"}]}
                                                                                                                       ~~~~~~~~~~~~~~~
 
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Part of 'files' list in tsconfig.json
 [12:02:16 AM] Found 1 error. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -1086,12 +1294,27 @@ Output::
 >> Screen clear
 [12:02:20 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../b' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b/index.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/b/index.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/a/index.ts'.
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a/index.d.ts
+  Imported via '@ref/a' from file 'b/index.d.ts'
+  File is output of project reference source 'a/index.ts'
+b/index.d.ts
+  Imported via '../b' from file 'c/index.ts'
+  File is output of project reference source 'b/index.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c/index.ts'
+c/index.ts
+  Part of 'files' list in tsconfig.json
 [12:02:21 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c/index.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences/c","paths":{"@ref/*":["../refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences/c","watch":true,"project":"/user/username/projects/transitiveReferences/c","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/c/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts

tests/baselines/reference/tscWatch/projectsWithReferences/on-transitive-references.js

@@ -210,17 +210,49 @@ a_1.X;
 
 
 
-/a/lib/tsc.js -w -p tsconfig.c.json
+/a/lib/tsc.js -w -p tsconfig.c.json --traceResolution --explainFiles
 Output::
 >> Screen clear
 [12:00:53 AM] Starting compilation in watch mode...
 
+======== Resolving module './b' from '/user/username/projects/transitiveReferences/c.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/b', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/b.ts' exist - use it as a name resolution result.
+======== Module name './b' was successfully resolved to '/user/username/projects/transitiveReferences/b.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/c.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution './refs/*', candidate module location: './refs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/refs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/refs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/tsconfig.b.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/a.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a.d.ts
+  Imported via '@ref/a' from file 'b.d.ts'
+  File is output of project reference source 'a.ts'
+b.d.ts
+  Imported via './b' from file 'c.ts'
+  File is output of project reference source 'b.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c.ts'
+c.ts
+  Part of 'files' list in tsconfig.json
 [12:00:57 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -385,12 +417,25 @@ Output::
 >> Screen clear
 [12:01:13 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/b.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/a.ts'.
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a.d.ts
+  Imported via '@ref/a' from file 'b.d.ts'
+  File is output of project reference source 'a.ts'
+b.d.ts
+  Imported via './b' from file 'c.ts'
+  File is output of project reference source 'b.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c.ts'
+c.ts
+  Part of 'files' list in tsconfig.json
 [12:01:17 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
 Program structureReused: Completely
 Program files::
 /a/lib/lib.d.ts
@@ -473,12 +518,44 @@ Output::
 >> Screen clear
 [12:01:25 AM] File change detected. Starting incremental compilation...
 
+======== Resolving module './b' from '/user/username/projects/transitiveReferences/c.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/b', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/b.ts' exist - use it as a name resolution result.
+======== Module name './b' was successfully resolved to '/user/username/projects/transitiveReferences/b.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/c.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution './nrefs/*', candidate module location: './nrefs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/nrefs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/nrefs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/nrefs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/nrefs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/nrefs/a.d.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/tsconfig.b.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/a.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a.d.ts
+  Imported via '@ref/a' from file 'b.d.ts'
+  File is output of project reference source 'a.ts'
+b.d.ts
+  Imported via './b' from file 'c.ts'
+  File is output of project reference source 'b.ts'
+nrefs/a.d.ts
+  Imported via "@ref/a" from file 'c.ts'
+c.ts
+  Part of 'files' list in tsconfig.json
 [12:01:29 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./nrefs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./nrefs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -556,12 +633,44 @@ Output::
 >> Screen clear
 [12:01:33 AM] File change detected. Starting incremental compilation...
 
+======== Resolving module './b' from '/user/username/projects/transitiveReferences/c.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/b', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/b.ts' exist - use it as a name resolution result.
+======== Module name './b' was successfully resolved to '/user/username/projects/transitiveReferences/b.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/c.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution './refs/*', candidate module location: './refs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/refs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/refs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/tsconfig.b.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/a.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a.d.ts
+  Imported via '@ref/a' from file 'b.d.ts'
+  File is output of project reference source 'a.ts'
+b.d.ts
+  Imported via './b' from file 'c.ts'
+  File is output of project reference source 'b.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c.ts'
+c.ts
+  Part of 'files' list in tsconfig.json
 [12:01:37 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -639,12 +748,29 @@ Output::
 >> Screen clear
 [12:01:41 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module './b' from '/user/username/projects/transitiveReferences/c.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/tsconfig.b.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/nrefs/a.d.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+nrefs/a.d.ts
+  Imported via '@ref/a' from file 'b.d.ts'
+b.d.ts
+  Imported via './b' from file 'c.ts'
+  File is output of project reference source 'b.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c.ts'
+c.ts
+  Part of 'files' list in tsconfig.json
 [12:01:42 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -723,12 +849,28 @@ Output::
 >> Screen clear
 [12:01:47 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module './b' from '/user/username/projects/transitiveReferences/c.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/tsconfig.b.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+refs/a.d.ts
+  Imported via '@ref/a' from file 'b.d.ts'
+  Imported via "@ref/a" from file 'c.ts'
+b.d.ts
+  Imported via './b' from file 'c.ts'
+  File is output of project reference source 'b.ts'
+c.ts
+  Part of 'files' list in tsconfig.json
 [12:01:48 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -794,17 +936,39 @@ Output::
 >> Screen clear
 [12:01:50 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module './b' from '/user/username/projects/transitiveReferences/c.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution './refs/*', candidate module location: './refs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/refs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/refs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
 tsconfig.c.json:1:100 - error TS6053: File '/user/username/projects/transitiveReferences/tsconfig.b.json' not found.
 
 1 {"files":["c.ts"],"compilerOptions":{"baseUrl":"./","paths":{"@ref/*":["./refs/*"]}},"references":[{"path":"tsconfig.b.json"}]}
                                                                                                      ~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+refs/a.d.ts
+  Imported via '@ref/a' from file 'b.ts'
+  Imported via "@ref/a" from file 'c.ts'
+b.ts
+  Imported via './b' from file 'c.ts'
+c.ts
+  Part of 'files' list in tsconfig.json
 [12:01:57 AM] Found 1 error. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -885,12 +1049,30 @@ Output::
 >> Screen clear
 [12:02:00 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module './b' from '/user/username/projects/transitiveReferences/c.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/b.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/tsconfig.b.json'.
+Module resolution kind is not specified, using 'NodeJs'.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/a.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a.d.ts
+  Imported via '@ref/a' from file 'b.d.ts'
+  File is output of project reference source 'a.ts'
+b.d.ts
+  Imported via './b' from file 'c.ts'
+  File is output of project reference source 'b.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c.ts'
+c.ts
+  Part of 'files' list in tsconfig.json
 [12:02:04 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -968,17 +1150,31 @@ Output::
 >> Screen clear
 [12:02:06 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module './b' from '/user/username/projects/transitiveReferences/c.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/b.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/a.ts'.
 tsconfig.b.json:10:21 - error TS6053: File '/user/username/projects/transitiveReferences/tsconfig.a.json' not found.
 
 10     "references": [ { "path": "tsconfig.a.json" } ]
                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a.ts
+  Imported via '@ref/a' from file 'b.d.ts'
+b.d.ts
+  Imported via './b' from file 'c.ts'
+  File is output of project reference source 'b.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c.ts'
+c.ts
+  Part of 'files' list in tsconfig.json
 [12:02:10 AM] Found 1 error. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -1057,12 +1253,27 @@ Output::
 >> Screen clear
 [12:02:14 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module './b' from '/user/username/projects/transitiveReferences/c.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/b.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/c.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'.
+Reusing resolution of module '@ref/a' from '/user/username/projects/transitiveReferences/b.ts' of old program, it was successfully resolved to '/user/username/projects/transitiveReferences/a.ts'.
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a.d.ts
+  Imported via '@ref/a' from file 'b.d.ts'
+  File is output of project reference source 'a.ts'
+b.d.ts
+  Imported via './b' from file 'c.ts'
+  File is output of project reference source 'b.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c.ts'
+c.ts
+  Part of 'files' list in tsconfig.json
 [12:02:15 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts

tests/baselines/reference/tscWatch/projectsWithReferences/when-declarationMap-changes-for-dependency.js

@@ -163,17 +163,37 @@ export declare function multiply(a: number, b: number): number;
 }
 
 
-/a/lib/tsc.js -w -p logic
+/a/lib/tsc.js -w -p logic --traceResolution --explainFiles
 Output::
 >> Screen clear
 [12:00:50 AM] Starting compilation in watch mode...
 
+======== Resolving module '../core/index' from '/user/username/projects/sample1/logic/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/sample1/core/index', target file types: TypeScript, Declaration.
+File '/user/username/projects/sample1/core/index.ts' exist - use it as a name resolution result.
+======== Module name '../core/index' was successfully resolved to '/user/username/projects/sample1/core/index.ts'. ========
+======== Resolving module '../core/anotherModule' from '/user/username/projects/sample1/logic/index.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/sample1/core/anotherModule', target file types: TypeScript, Declaration.
+File '/user/username/projects/sample1/core/anotherModule.ts' exist - use it as a name resolution result.
+======== Module name '../core/anotherModule' was successfully resolved to '/user/username/projects/sample1/core/anotherModule.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+core/index.d.ts
+  Imported via '../core/index' from file 'logic/index.ts'
+  File is output of project reference source 'core/index.ts'
+core/anotherModule.d.ts
+  Imported via '../core/anotherModule' from file 'logic/index.ts'
+  File is output of project reference source 'core/anotherModule.ts'
+logic/index.ts
+  Matched by default include pattern '**/*'
 [12:00:59 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/sample1/logic/index.ts"]
-Program options: {"composite":true,"declaration":true,"sourceMap":true,"forceConsistentCasingInFileNames":true,"skipDefaultLibCheck":true,"watch":true,"project":"/user/username/projects/sample1/logic","configFilePath":"/user/username/projects/sample1/logic/tsconfig.json"}
+Program options: {"composite":true,"declaration":true,"sourceMap":true,"forceConsistentCasingInFileNames":true,"skipDefaultLibCheck":true,"watch":true,"project":"/user/username/projects/sample1/logic","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/sample1/logic/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -432,12 +452,24 @@ Output::
 >> Screen clear
 [12:01:18 AM] File change detected. Starting incremental compilation...
 
+Reusing resolution of module '../core/index' from '/user/username/projects/sample1/logic/index.ts' of old program, it was successfully resolved to '/user/username/projects/sample1/core/index.ts'.
+Reusing resolution of module '../core/anotherModule' from '/user/username/projects/sample1/logic/index.ts' of old program, it was successfully resolved to '/user/username/projects/sample1/core/anotherModule.ts'.
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+core/index.d.ts
+  Imported via '../core/index' from file 'logic/index.ts'
+  File is output of project reference source 'core/index.ts'
+core/anotherModule.d.ts
+  Imported via '../core/anotherModule' from file 'logic/index.ts'
+  File is output of project reference source 'core/anotherModule.ts'
+logic/index.ts
+  Matched by default include pattern '**/*'
 [12:01:19 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/sample1/logic/index.ts"]
-Program options: {"composite":true,"declaration":true,"sourceMap":true,"forceConsistentCasingInFileNames":true,"skipDefaultLibCheck":true,"watch":true,"project":"/user/username/projects/sample1/logic","configFilePath":"/user/username/projects/sample1/logic/tsconfig.json"}
+Program options: {"composite":true,"declaration":true,"sourceMap":true,"forceConsistentCasingInFileNames":true,"skipDefaultLibCheck":true,"watch":true,"project":"/user/username/projects/sample1/logic","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/sample1/logic/tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts

tests/baselines/reference/tscWatch/projectsWithReferences/when-referenced-project-uses-different-module-resolution.js

@@ -197,17 +197,49 @@ a_1.X;
 
 
 
-/a/lib/tsc.js -w -p tsconfig.c.json
+/a/lib/tsc.js -w -p tsconfig.c.json --traceResolution --explainFiles
 Output::
 >> Screen clear
 [12:00:53 AM] Starting compilation in watch mode...
 
+======== Resolving module './b' from '/user/username/projects/transitiveReferences/c.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/b', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/b.ts' exist - use it as a name resolution result.
+======== Module name './b' was successfully resolved to '/user/username/projects/transitiveReferences/b.ts'. ========
+======== Resolving module '@ref/a' from '/user/username/projects/transitiveReferences/c.ts'. ========
+Module resolution kind is not specified, using 'NodeJs'.
+'baseUrl' option is set to '/user/username/projects/transitiveReferences', using this value to resolve non-relative module name '@ref/a'.
+'paths' option is specified, looking for a pattern to match module name '@ref/a'.
+Module name '@ref/a', matched pattern '@ref/*'.
+Trying substitution './refs/*', candidate module location: './refs/a'.
+Loading module as file / folder, candidate module location '/user/username/projects/transitiveReferences/refs/a', target file types: TypeScript, Declaration.
+File '/user/username/projects/transitiveReferences/refs/a.ts' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.tsx' does not exist.
+File '/user/username/projects/transitiveReferences/refs/a.d.ts' exist - use it as a name resolution result.
+======== Module name '@ref/a' was successfully resolved to '/user/username/projects/transitiveReferences/refs/a.d.ts'. ========
+======== Resolving module 'a' from '/user/username/projects/transitiveReferences/b.ts'. ========
+Using compiler options of project reference redirect '/user/username/projects/transitiveReferences/tsconfig.b.json'.
+Explicitly specified module resolution kind: 'Classic'.
+======== Module name 'a' was successfully resolved to '/user/username/projects/transitiveReferences/a.ts'. ========
+../../../../a/lib/lib.d.ts
+  Default library for target 'es3'
+a.d.ts
+  Imported via "a" from file 'b.d.ts'
+  File is output of project reference source 'a.ts'
+b.d.ts
+  Imported via './b' from file 'c.ts'
+  File is output of project reference source 'b.ts'
+refs/a.d.ts
+  Imported via "@ref/a" from file 'c.ts'
+c.ts
+  Part of 'files' list in tsconfig.json
 [12:00:57 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/user/username/projects/transitiveReferences/c.ts"]
-Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
+Program options: {"baseUrl":"/user/username/projects/transitiveReferences","paths":{"@ref/*":["./refs/*"]},"pathsBasePath":"/user/username/projects/transitiveReferences","watch":true,"project":"/user/username/projects/transitiveReferences/tsconfig.c.json","traceResolution":true,"explainFiles":true,"configFilePath":"/user/username/projects/transitiveReferences/tsconfig.c.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts

tests/baselines/reference/tsserver/resolutionCache/non-relative-module-name-from-files-in-same-folder.js

@@ -81,18 +81,22 @@ Info 34   [00:01:11.000] DirectoryWatcher:: Added:: WatchInfo: /user/username/pr
 Info 35   [00:01:12.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/src/node_modules 1 undefined WatchType: node_modules for closed script infos and package.jsons affecting module specifier cache
 Info 36   [00:01:13.000] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules 1 undefined WatchType: node_modules for closed script infos and package.jsons affecting module specifier cache
 Info 37   [00:01:14.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules 1 undefined WatchType: node_modules for closed script infos and package.jsons affecting module specifier cache
-Info 38   [00:01:15.000] Reusing resolution of module 'module1' from '/user/username/projects/myproject/src/file2.ts' found in cache from location '/user/username/projects/myproject/src', it was successfully resolved to '/user/username/projects/myproject/src/node_modules/module1/index.ts'.
-Info 39   [00:01:16.000] Reusing resolution of module 'module2' from '/user/username/projects/myproject/src/file2.ts' found in cache from location '/user/username/projects/myproject/src', it was successfully resolved to '/user/username/projects/myproject/node_modules/module2/index.ts'.
-Info 40   [00:01:17.000] FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined WatchType: Closed Script info
-Info 41   [00:01:18.000] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/src 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Failed Lookup Locations
-Info 42   [00:01:19.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/src 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Failed Lookup Locations
-Info 43   [00:01:20.000] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Failed Lookup Locations
-Info 44   [00:01:21.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Failed Lookup Locations
-Info 45   [00:01:22.000] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
-Info 46   [00:01:23.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
-Info 47   [00:01:24.000] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 1 structureChanged: true structureIsReused:: Not Elapsed:: *ms
-Info 48   [00:01:25.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
-Info 49   [00:01:26.000] 	Files (5)
+Info 38   [00:01:15.000] ======== Resolving module 'module1' from '/user/username/projects/myproject/src/file2.ts'. ========
+Info 39   [00:01:16.000] Resolution for module 'module1' was found in cache from location '/user/username/projects/myproject/src'.
+Info 40   [00:01:17.000] ======== Module name 'module1' was successfully resolved to '/user/username/projects/myproject/src/node_modules/module1/index.ts'. ========
+Info 41   [00:01:18.000] ======== Resolving module 'module2' from '/user/username/projects/myproject/src/file2.ts'. ========
+Info 42   [00:01:19.000] Resolution for module 'module2' was found in cache from location '/user/username/projects/myproject/src'.
+Info 43   [00:01:20.000] ======== Module name 'module2' was successfully resolved to '/user/username/projects/myproject/node_modules/module2/index.ts'. ========
+Info 44   [00:01:21.000] FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined WatchType: Closed Script info
+Info 45   [00:01:22.000] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/src 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Failed Lookup Locations
+Info 46   [00:01:23.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/src 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Failed Lookup Locations
+Info 47   [00:01:24.000] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Failed Lookup Locations
+Info 48   [00:01:25.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Failed Lookup Locations
+Info 49   [00:01:26.000] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
+Info 50   [00:01:27.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
+Info 51   [00:01:28.000] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 1 structureChanged: true structureIsReused:: Not Elapsed:: *ms
+Info 52   [00:01:29.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info 53   [00:01:30.000] 	Files (5)
 	/a/lib/lib.d.ts
 	/user/username/projects/myproject/src/node_modules/module1/index.ts
 	/user/username/projects/myproject/node_modules/module2/index.ts
@@ -113,18 +117,18 @@ Info 49   [00:01:26.000] 	Files (5)
 	src/file2.ts
 	  Matched by default include pattern '**/*'
 
-Info 50   [00:01:27.000] -----------------------------------------------
-Info 51   [00:01:28.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
-Info 51   [00:01:29.000] 	Files (5)
+Info 54   [00:01:31.000] -----------------------------------------------
+Info 55   [00:01:32.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info 55   [00:01:33.000] 	Files (5)
 
-Info 51   [00:01:30.000] -----------------------------------------------
-Info 51   [00:01:31.000] Open files: 
-Info 51   [00:01:32.000] 	FileName: /user/username/projects/myproject/src/file1.ts ProjectRootPath: undefined
-Info 51   [00:01:33.000] 		Projects: /user/username/projects/myproject/tsconfig.json
-Info 51   [00:01:40.000] FileWatcher:: Triggered with /user/username/projects/myproject/src/file2.ts 1:: WatchInfo: /user/username/projects/myproject/src/file2.ts 500 undefined WatchType: Closed Script info
-Info 52   [00:01:41.000] Scheduled: /user/username/projects/myproject/tsconfig.json
-Info 53   [00:01:42.000] Scheduled: *ensureProjectForOpenFiles*
-Info 54   [00:01:43.000] Elapsed:: *ms FileWatcher:: Triggered with /user/username/projects/myproject/src/file2.ts 1:: WatchInfo: /user/username/projects/myproject/src/file2.ts 500 undefined WatchType: Closed Script info
+Info 55   [00:01:34.000] -----------------------------------------------
+Info 55   [00:01:35.000] Open files: 
+Info 55   [00:01:36.000] 	FileName: /user/username/projects/myproject/src/file1.ts ProjectRootPath: undefined
+Info 55   [00:01:37.000] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info 55   [00:01:44.000] FileWatcher:: Triggered with /user/username/projects/myproject/src/file2.ts 1:: WatchInfo: /user/username/projects/myproject/src/file2.ts 500 undefined WatchType: Closed Script info
+Info 56   [00:01:45.000] Scheduled: /user/username/projects/myproject/tsconfig.json
+Info 57   [00:01:46.000] Scheduled: *ensureProjectForOpenFiles*
+Info 58   [00:01:47.000] Elapsed:: *ms FileWatcher:: Triggered with /user/username/projects/myproject/src/file2.ts 1:: WatchInfo: /user/username/projects/myproject/src/file2.ts 500 undefined WatchType: Closed Script info
 Before running timeout callbacks
 //// [/user/username/projects/myproject/src/file1.ts]
 import { module1 } from "module1";import { module2 } from "module2";import { module1 } from "module1";import { module2 } from "module2";
@@ -155,31 +159,31 @@ FsWatchesRecursive::
 /user/username/projects/myproject/src:
   {}
 
-Info 55   [00:01:44.000] Running: /user/username/projects/myproject/tsconfig.json
-Info 56   [00:01:45.000] Starting updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json
-Info 57   [00:01:46.000] Reusing resolution of module 'module1' from '/user/username/projects/myproject/src/file1.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/src/node_modules/module1/index.ts'.
-Info 58   [00:01:47.000] Reusing resolution of module 'module2' from '/user/username/projects/myproject/src/file1.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/node_modules/module2/index.ts'.
-Info 59   [00:01:48.000] Reusing resolution of module 'module1' from '/user/username/projects/myproject/src/file2.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/src/node_modules/module1/index.ts'.
-Info 60   [00:01:49.000] Reusing resolution of module 'module2' from '/user/username/projects/myproject/src/file2.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/node_modules/module2/index.ts'.
-Info 61   [00:01:50.000] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 2 structureChanged: true structureIsReused:: SafeModules Elapsed:: *ms
-Info 62   [00:01:51.000] Different program with same set of files
-Info 63   [00:01:52.000] Running: *ensureProjectForOpenFiles*
-Info 64   [00:01:53.000] Before ensureProjectForOpenFiles:
-Info 65   [00:01:54.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
-Info 65   [00:01:55.000] 	Files (5)
+Info 59   [00:01:48.000] Running: /user/username/projects/myproject/tsconfig.json
+Info 60   [00:01:49.000] Starting updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json
+Info 61   [00:01:50.000] Reusing resolution of module 'module1' from '/user/username/projects/myproject/src/file1.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/src/node_modules/module1/index.ts'.
+Info 62   [00:01:51.000] Reusing resolution of module 'module2' from '/user/username/projects/myproject/src/file1.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/node_modules/module2/index.ts'.
+Info 63   [00:01:52.000] Reusing resolution of module 'module1' from '/user/username/projects/myproject/src/file2.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/src/node_modules/module1/index.ts'.
+Info 64   [00:01:53.000] Reusing resolution of module 'module2' from '/user/username/projects/myproject/src/file2.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/node_modules/module2/index.ts'.
+Info 65   [00:01:54.000] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 2 structureChanged: true structureIsReused:: SafeModules Elapsed:: *ms
+Info 66   [00:01:55.000] Different program with same set of files
+Info 67   [00:01:56.000] Running: *ensureProjectForOpenFiles*
+Info 68   [00:01:57.000] Before ensureProjectForOpenFiles:
+Info 69   [00:01:58.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info 69   [00:01:59.000] 	Files (5)
 
-Info 65   [00:01:56.000] -----------------------------------------------
-Info 65   [00:01:57.000] Open files: 
-Info 65   [00:01:58.000] 	FileName: /user/username/projects/myproject/src/file1.ts ProjectRootPath: undefined
-Info 65   [00:01:59.000] 		Projects: /user/username/projects/myproject/tsconfig.json
-Info 65   [00:02:00.000] After ensureProjectForOpenFiles:
-Info 66   [00:02:01.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
-Info 66   [00:02:02.000] 	Files (5)
+Info 69   [00:02:00.000] -----------------------------------------------
+Info 69   [00:02:01.000] Open files: 
+Info 69   [00:02:02.000] 	FileName: /user/username/projects/myproject/src/file1.ts ProjectRootPath: undefined
+Info 69   [00:02:03.000] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info 69   [00:02:04.000] After ensureProjectForOpenFiles:
+Info 70   [00:02:05.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info 70   [00:02:06.000] 	Files (5)
 
-Info 66   [00:02:03.000] -----------------------------------------------
-Info 66   [00:02:04.000] Open files: 
-Info 66   [00:02:05.000] 	FileName: /user/username/projects/myproject/src/file1.ts ProjectRootPath: undefined
-Info 66   [00:02:06.000] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info 70   [00:02:07.000] -----------------------------------------------
+Info 70   [00:02:08.000] Open files: 
+Info 70   [00:02:09.000] 	FileName: /user/username/projects/myproject/src/file1.ts ProjectRootPath: undefined
+Info 70   [00:02:10.000] 		Projects: /user/username/projects/myproject/tsconfig.json
 After running timeout callbacks
 
 PolledWatches::

tests/baselines/reference/tsserver/resolutionCache/not-sharing-across-references.js

@@ -0,0 +1,182 @@
+Info 0    [00:00:29.000] Provided types map file "/a/lib/typesMap.json" doesn't exist
+Info 1    [00:00:30.000] request:
+    {
+      "command": "open",
+      "arguments": {
+        "file": "/src/projects/app/appB.ts"
+      },
+      "seq": 1,
+      "type": "request"
+    }
+Before request
+//// [/src/projects/node_modules/moduleX/index.d.ts]
+export const x = 10;
+
+//// [/src/projects/common/tsconfig.json]
+{"compilerOptions":{"composite":true,"traceResolution":true}}
+
+//// [/src/projects/common/moduleA.ts]
+export const a = 10;
+
+//// [/src/projects/common/moduleB.ts]
+import { x } from "moduleX";
+export const b = x;
+
+
+//// [/src/projects/app/tsconfig.json]
+{"compilerOptions":{"composite":true,"traceResolution":true,"typeRoots":[]},"references":[{"path":"../common"}]}
+
+//// [/src/projects/app/appA.ts]
+import { x } from "moduleX";
+export const y = x;
+
+
+//// [/src/projects/app/appB.ts]
+import { x } from "../common/moduleB";
+export const y = x;
+
+
+
+PolledWatches::
+
+FsWatches::
+
+FsWatchesRecursive::
+
+Info 2    [00:00:31.000] Search path: /src/projects/app
+Info 3    [00:00:32.000] For info: /src/projects/app/appB.ts :: Config file name: /src/projects/app/tsconfig.json
+Info 4    [00:00:33.000] Creating configuration project /src/projects/app/tsconfig.json
+Info 5    [00:00:34.000] FileWatcher:: Added:: WatchInfo: /src/projects/app/tsconfig.json 2000 undefined Project: /src/projects/app/tsconfig.json WatchType: Config file
+Info 6    [00:00:35.000] Config: /src/projects/app/tsconfig.json : {
+ "rootNames": [
+  "/src/projects/app/appA.ts",
+  "/src/projects/app/appB.ts"
+ ],
+ "options": {
+  "composite": true,
+  "traceResolution": true,
+  "typeRoots": [],
+  "configFilePath": "/src/projects/app/tsconfig.json"
+ },
+ "projectReferences": [
+  {
+   "path": "/src/projects/common",
+   "originalPath": "../common"
+  }
+ ]
+}
+Info 7    [00:00:36.000] DirectoryWatcher:: Added:: WatchInfo: /src/projects/app 1 undefined Config: /src/projects/app/tsconfig.json WatchType: Wild card directory
+Info 8    [00:00:37.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /src/projects/app 1 undefined Config: /src/projects/app/tsconfig.json WatchType: Wild card directory
+Info 9    [00:00:38.000] FileWatcher:: Added:: WatchInfo: /src/projects/app/appA.ts 500 undefined WatchType: Closed Script info
+Info 10   [00:00:39.000] Starting updateGraphWorker: Project: /src/projects/app/tsconfig.json
+Info 11   [00:00:40.000] Config: /src/projects/common/tsconfig.json : {
+ "rootNames": [
+  "/src/projects/common/moduleA.ts",
+  "/src/projects/common/moduleB.ts"
+ ],
+ "options": {
+  "composite": true,
+  "traceResolution": true,
+  "configFilePath": "/src/projects/common/tsconfig.json"
+ }
+}
+Info 12   [00:00:41.000] FileWatcher:: Added:: WatchInfo: /src/projects/common/tsconfig.json 2000 undefined Project: /src/projects/app/tsconfig.json WatchType: Config file
+Info 13   [00:00:42.000] DirectoryWatcher:: Added:: WatchInfo: /src/projects/common 1 undefined Config: /src/projects/common/tsconfig.json WatchType: Wild card directory
+Info 14   [00:00:43.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /src/projects/common 1 undefined Config: /src/projects/common/tsconfig.json WatchType: Wild card directory
+Info 15   [00:00:44.000] ======== Resolving module 'moduleX' from '/src/projects/app/appA.ts'. ========
+Info 16   [00:00:45.000] Module resolution kind is not specified, using 'NodeJs'.
+Info 17   [00:00:46.000] Loading module 'moduleX' from 'node_modules' folder, target file types: TypeScript, Declaration.
+Info 18   [00:00:47.000] Directory '/src/projects/app/node_modules' does not exist, skipping all lookups in it.
+Info 19   [00:00:48.000] File '/src/projects/node_modules/moduleX/package.json' does not exist.
+Info 20   [00:00:49.000] File '/src/projects/node_modules/moduleX.ts' does not exist.
+Info 21   [00:00:50.000] File '/src/projects/node_modules/moduleX.tsx' does not exist.
+Info 22   [00:00:51.000] File '/src/projects/node_modules/moduleX.d.ts' does not exist.
+Info 23   [00:00:52.000] File '/src/projects/node_modules/moduleX/index.ts' does not exist.
+Info 24   [00:00:53.000] File '/src/projects/node_modules/moduleX/index.tsx' does not exist.
+Info 25   [00:00:54.000] File '/src/projects/node_modules/moduleX/index.d.ts' exist - use it as a name resolution result.
+Info 26   [00:00:55.000] Resolving real path for '/src/projects/node_modules/moduleX/index.d.ts', result '/src/projects/node_modules/moduleX/index.d.ts'.
+Info 27   [00:00:56.000] ======== Module name 'moduleX' was successfully resolved to '/src/projects/node_modules/moduleX/index.d.ts'. ========
+Info 28   [00:00:57.000] DirectoryWatcher:: Added:: WatchInfo: /src/projects/node_modules 1 undefined WatchType: node_modules for closed script infos and package.jsons affecting module specifier cache
+Info 29   [00:00:58.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /src/projects/node_modules 1 undefined WatchType: node_modules for closed script infos and package.jsons affecting module specifier cache
+Info 30   [00:00:59.000] ======== Resolving module '../common/moduleB' from '/src/projects/app/appB.ts'. ========
+Info 31   [00:01:00.000] Module resolution kind is not specified, using 'NodeJs'.
+Info 32   [00:01:01.000] Loading module as file / folder, candidate module location '/src/projects/common/moduleB', target file types: TypeScript, Declaration.
+Info 33   [00:01:02.000] File '/src/projects/common/moduleB.ts' exist - use it as a name resolution result.
+Info 34   [00:01:03.000] ======== Module name '../common/moduleB' was successfully resolved to '/src/projects/common/moduleB.ts'. ========
+Info 35   [00:01:04.000] FileWatcher:: Added:: WatchInfo: /src/projects/common/moduleB.ts 500 undefined WatchType: Closed Script info
+Info 36   [00:01:05.000] ======== Resolving module 'moduleX' from '/src/projects/common/moduleB.ts'. ========
+Info 37   [00:01:06.000] Using compiler options of project reference redirect '/src/projects/common/tsconfig.json'.
+Info 38   [00:01:07.000] Module resolution kind is not specified, using 'NodeJs'.
+Info 39   [00:01:08.000] Loading module 'moduleX' from 'node_modules' folder, target file types: TypeScript, Declaration.
+Info 40   [00:01:09.000] Directory '/src/projects/common/node_modules' does not exist, skipping all lookups in it.
+Info 41   [00:01:10.000] File '/src/projects/node_modules/moduleX/package.json' does not exist according to earlier cached lookups.
+Info 42   [00:01:11.000] File '/src/projects/node_modules/moduleX.ts' does not exist.
+Info 43   [00:01:12.000] File '/src/projects/node_modules/moduleX.tsx' does not exist.
+Info 44   [00:01:13.000] File '/src/projects/node_modules/moduleX.d.ts' does not exist.
+Info 45   [00:01:14.000] File '/src/projects/node_modules/moduleX/index.ts' does not exist.
+Info 46   [00:01:15.000] File '/src/projects/node_modules/moduleX/index.tsx' does not exist.
+Info 47   [00:01:16.000] File '/src/projects/node_modules/moduleX/index.d.ts' exist - use it as a name resolution result.
+Info 48   [00:01:17.000] Resolving real path for '/src/projects/node_modules/moduleX/index.d.ts', result '/src/projects/node_modules/moduleX/index.d.ts'.
+Info 49   [00:01:18.000] ======== Module name 'moduleX' was successfully resolved to '/src/projects/node_modules/moduleX/index.d.ts'. ========
+Info 50   [00:01:19.000] DirectoryWatcher:: Added:: WatchInfo: /src/projects/app/node_modules 1 undefined Project: /src/projects/app/tsconfig.json WatchType: Failed Lookup Locations
+Info 51   [00:01:20.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /src/projects/app/node_modules 1 undefined Project: /src/projects/app/tsconfig.json WatchType: Failed Lookup Locations
+Info 52   [00:01:21.000] FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined Project: /src/projects/app/tsconfig.json WatchType: Missing file
+Info 53   [00:01:22.000] Finishing updateGraphWorker: Project: /src/projects/app/tsconfig.json Version: 1 structureChanged: true structureIsReused:: Not Elapsed:: *ms
+Info 54   [00:01:23.000] Project '/src/projects/app/tsconfig.json' (Configured)
+Info 55   [00:01:24.000] 	Files (4)
+	/src/projects/node_modules/moduleX/index.d.ts
+	/src/projects/app/appA.ts
+	/src/projects/common/moduleB.ts
+	/src/projects/app/appB.ts
+
+
+	../node_modules/moduleX/index.d.ts
+	  Imported via "moduleX" from file 'appA.ts'
+	  Imported via "moduleX" from file '../common/moduleB.ts'
+	appA.ts
+	  Matched by default include pattern '**/*'
+	../common/moduleB.ts
+	  Imported via "../common/moduleB" from file 'appB.ts'
+	appB.ts
+	  Matched by default include pattern '**/*'
+
+Info 56   [00:01:25.000] -----------------------------------------------
+Info 57   [00:01:26.000] Search path: /src/projects/app
+Info 58   [00:01:27.000] For info: /src/projects/app/tsconfig.json :: No config files found.
+Info 59   [00:01:28.000] Project '/src/projects/app/tsconfig.json' (Configured)
+Info 59   [00:01:29.000] 	Files (4)
+
+Info 59   [00:01:30.000] -----------------------------------------------
+Info 59   [00:01:31.000] Open files: 
+Info 59   [00:01:32.000] 	FileName: /src/projects/app/appB.ts ProjectRootPath: undefined
+Info 59   [00:01:33.000] 		Projects: /src/projects/app/tsconfig.json
+After request
+
+PolledWatches::
+/src/projects/app/node_modules:
+  {"pollingInterval":500}
+/a/lib/lib.d.ts:
+  {"pollingInterval":500}
+
+FsWatches::
+/src/projects/app/tsconfig.json:
+  {}
+/src/projects/app/appa.ts:
+  {}
+/src/projects/common/tsconfig.json:
+  {}
+/src/projects/common/moduleb.ts:
+  {}
+
+FsWatchesRecursive::
+/src/projects/app:
+  {}
+/src/projects/common:
+  {}
+/src/projects/node_modules:
+  {}
+
+Info 59   [00:01:34.000] response:
+    {
+      "responseRequired": false
+    }

tests/baselines/reference/tsserver/resolutionCache/relative-module-name-from-files-in-same-folder.js

@@ -67,14 +67,18 @@ Info 18   [00:00:47.000] Module resolution kind is not specified, using 'NodeJs'
 Info 19   [00:00:48.000] Loading module as file / folder, candidate module location '/user/username/projects/myproject/module2', target file types: TypeScript, Declaration.
 Info 20   [00:00:49.000] File '/user/username/projects/myproject/module2.ts' exist - use it as a name resolution result.
 Info 21   [00:00:50.000] ======== Module name '../module2' was successfully resolved to '/user/username/projects/myproject/module2.ts'. ========
-Info 22   [00:00:51.000] Reusing resolution of module './module1' from '/user/username/projects/myproject/src/file2.ts' found in cache from location '/user/username/projects/myproject/src', it was successfully resolved to '/user/username/projects/myproject/src/module1.ts'.
-Info 23   [00:00:52.000] Reusing resolution of module '../module2' from '/user/username/projects/myproject/src/file2.ts' found in cache from location '/user/username/projects/myproject/src', it was successfully resolved to '/user/username/projects/myproject/module2.ts'.
-Info 24   [00:00:53.000] FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined WatchType: Closed Script info
-Info 25   [00:00:54.000] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
-Info 26   [00:00:55.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
-Info 27   [00:00:56.000] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 1 structureChanged: true structureIsReused:: Not Elapsed:: *ms
-Info 28   [00:00:57.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
-Info 29   [00:00:58.000] 	Files (5)
+Info 22   [00:00:51.000] ======== Resolving module './module1' from '/user/username/projects/myproject/src/file2.ts'. ========
+Info 23   [00:00:52.000] Resolution for module './module1' was found in cache from location '/user/username/projects/myproject/src'.
+Info 24   [00:00:53.000] ======== Module name './module1' was successfully resolved to '/user/username/projects/myproject/src/module1.ts'. ========
+Info 25   [00:00:54.000] ======== Resolving module '../module2' from '/user/username/projects/myproject/src/file2.ts'. ========
+Info 26   [00:00:55.000] Resolution for module '../module2' was found in cache from location '/user/username/projects/myproject/src'.
+Info 27   [00:00:56.000] ======== Module name '../module2' was successfully resolved to '/user/username/projects/myproject/module2.ts'. ========
+Info 28   [00:00:57.000] FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined WatchType: Closed Script info
+Info 29   [00:00:58.000] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
+Info 30   [00:00:59.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
+Info 31   [00:01:00.000] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 1 structureChanged: true structureIsReused:: Not Elapsed:: *ms
+Info 32   [00:01:01.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info 33   [00:01:02.000] 	Files (5)
 	/a/lib/lib.d.ts
 	/user/username/projects/myproject/module2.ts
 	/user/username/projects/myproject/src/module1.ts
@@ -97,18 +101,18 @@ Info 29   [00:00:58.000] 	Files (5)
 	src/file2.ts
 	  Matched by default include pattern '**/*'
 
-Info 30   [00:00:59.000] -----------------------------------------------
-Info 31   [00:01:00.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
-Info 31   [00:01:01.000] 	Files (5)
+Info 34   [00:01:03.000] -----------------------------------------------
+Info 35   [00:01:04.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info 35   [00:01:05.000] 	Files (5)
 
-Info 31   [00:01:02.000] -----------------------------------------------
-Info 31   [00:01:03.000] Open files: 
-Info 31   [00:01:04.000] 	FileName: /user/username/projects/myproject/src/file1.ts ProjectRootPath: undefined
-Info 31   [00:01:05.000] 		Projects: /user/username/projects/myproject/tsconfig.json
-Info 31   [00:01:12.000] FileWatcher:: Triggered with /user/username/projects/myproject/src/file2.ts 1:: WatchInfo: /user/username/projects/myproject/src/file2.ts 500 undefined WatchType: Closed Script info
-Info 32   [00:01:13.000] Scheduled: /user/username/projects/myproject/tsconfig.json
-Info 33   [00:01:14.000] Scheduled: *ensureProjectForOpenFiles*
-Info 34   [00:01:15.000] Elapsed:: *ms FileWatcher:: Triggered with /user/username/projects/myproject/src/file2.ts 1:: WatchInfo: /user/username/projects/myproject/src/file2.ts 500 undefined WatchType: Closed Script info
+Info 35   [00:01:06.000] -----------------------------------------------
+Info 35   [00:01:07.000] Open files: 
+Info 35   [00:01:08.000] 	FileName: /user/username/projects/myproject/src/file1.ts ProjectRootPath: undefined
+Info 35   [00:01:09.000] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info 35   [00:01:16.000] FileWatcher:: Triggered with /user/username/projects/myproject/src/file2.ts 1:: WatchInfo: /user/username/projects/myproject/src/file2.ts 500 undefined WatchType: Closed Script info
+Info 36   [00:01:17.000] Scheduled: /user/username/projects/myproject/tsconfig.json
+Info 37   [00:01:18.000] Scheduled: *ensureProjectForOpenFiles*
+Info 38   [00:01:19.000] Elapsed:: *ms FileWatcher:: Triggered with /user/username/projects/myproject/src/file2.ts 1:: WatchInfo: /user/username/projects/myproject/src/file2.ts 500 undefined WatchType: Closed Script info
 Before running timeout callbacks
 //// [/user/username/projects/myproject/src/file1.ts]
 import { module1 } from "./module1";import { module2 } from "../module2";import { module1 } from "./module1";import { module2 } from "../module2";
@@ -137,31 +141,31 @@ FsWatchesRecursive::
 /user/username/projects/myproject:
   {}
 
-Info 35   [00:01:16.000] Running: /user/username/projects/myproject/tsconfig.json
-Info 36   [00:01:17.000] Starting updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json
-Info 37   [00:01:18.000] Reusing resolution of module './module1' from '/user/username/projects/myproject/src/file1.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/src/module1.ts'.
-Info 38   [00:01:19.000] Reusing resolution of module '../module2' from '/user/username/projects/myproject/src/file1.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/module2.ts'.
-Info 39   [00:01:20.000] Reusing resolution of module './module1' from '/user/username/projects/myproject/src/file2.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/src/module1.ts'.
-Info 40   [00:01:21.000] Reusing resolution of module '../module2' from '/user/username/projects/myproject/src/file2.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/module2.ts'.
-Info 41   [00:01:22.000] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 2 structureChanged: true structureIsReused:: SafeModules Elapsed:: *ms
-Info 42   [00:01:23.000] Different program with same set of files
-Info 43   [00:01:24.000] Running: *ensureProjectForOpenFiles*
-Info 44   [00:01:25.000] Before ensureProjectForOpenFiles:
-Info 45   [00:01:26.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
-Info 45   [00:01:27.000] 	Files (5)
+Info 39   [00:01:20.000] Running: /user/username/projects/myproject/tsconfig.json
+Info 40   [00:01:21.000] Starting updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json
+Info 41   [00:01:22.000] Reusing resolution of module './module1' from '/user/username/projects/myproject/src/file1.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/src/module1.ts'.
+Info 42   [00:01:23.000] Reusing resolution of module '../module2' from '/user/username/projects/myproject/src/file1.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/module2.ts'.
+Info 43   [00:01:24.000] Reusing resolution of module './module1' from '/user/username/projects/myproject/src/file2.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/src/module1.ts'.
+Info 44   [00:01:25.000] Reusing resolution of module '../module2' from '/user/username/projects/myproject/src/file2.ts' of old program, it was successfully resolved to '/user/username/projects/myproject/module2.ts'.
+Info 45   [00:01:26.000] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 2 structureChanged: true structureIsReused:: SafeModules Elapsed:: *ms
+Info 46   [00:01:27.000] Different program with same set of files
+Info 47   [00:01:28.000] Running: *ensureProjectForOpenFiles*
+Info 48   [00:01:29.000] Before ensureProjectForOpenFiles:
+Info 49   [00:01:30.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info 49   [00:01:31.000] 	Files (5)
 
-Info 45   [00:01:28.000] -----------------------------------------------
-Info 45   [00:01:29.000] Open files: 
-Info 45   [00:01:30.000] 	FileName: /user/username/projects/myproject/src/file1.ts ProjectRootPath: undefined
-Info 45   [00:01:31.000] 		Projects: /user/username/projects/myproject/tsconfig.json
-Info 45   [00:01:32.000] After ensureProjectForOpenFiles:
-Info 46   [00:01:33.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
-Info 46   [00:01:34.000] 	Files (5)
+Info 49   [00:01:32.000] -----------------------------------------------
+Info 49   [00:01:33.000] Open files: 
+Info 49   [00:01:34.000] 	FileName: /user/username/projects/myproject/src/file1.ts ProjectRootPath: undefined
+Info 49   [00:01:35.000] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info 49   [00:01:36.000] After ensureProjectForOpenFiles:
+Info 50   [00:01:37.000] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info 50   [00:01:38.000] 	Files (5)
 
-Info 46   [00:01:35.000] -----------------------------------------------
-Info 46   [00:01:36.000] Open files: 
-Info 46   [00:01:37.000] 	FileName: /user/username/projects/myproject/src/file1.ts ProjectRootPath: undefined
-Info 46   [00:01:38.000] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info 50   [00:01:39.000] -----------------------------------------------
+Info 50   [00:01:40.000] Open files: 
+Info 50   [00:01:41.000] 	FileName: /user/username/projects/myproject/src/file1.ts ProjectRootPath: undefined
+Info 50   [00:01:42.000] 		Projects: /user/username/projects/myproject/tsconfig.json
 After running timeout callbacks
 
 PolledWatches::

tests/baselines/reference/tsserver/resolutionCache/sharing-across-references.js

@@ -0,0 +1,178 @@
+Info 0    [00:00:29.000] Provided types map file "/a/lib/typesMap.json" doesn't exist
+Info 1    [00:00:30.000] request:
+    {
+      "command": "open",
+      "arguments": {
+        "file": "/src/projects/app/appB.ts"
+      },
+      "seq": 1,
+      "type": "request"
+    }
+Before request
+//// [/src/projects/node_modules/moduleX/index.d.ts]
+export const x = 10;
+
+//// [/src/projects/common/tsconfig.json]
+{"compilerOptions":{"composite":true,"traceResolution":true}}
+
+//// [/src/projects/common/moduleA.ts]
+export const a = 10;
+
+//// [/src/projects/common/moduleB.ts]
+import { x } from "moduleX";
+export const b = x;
+
+
+//// [/src/projects/app/tsconfig.json]
+{"compilerOptions":{"composite":true,"traceResolution":true},"references":[{"path":"../common"}]}
+
+//// [/src/projects/app/appA.ts]
+import { x } from "moduleX";
+export const y = x;
+
+
+//// [/src/projects/app/appB.ts]
+import { x } from "../common/moduleB";
+export const y = x;
+
+
+
+PolledWatches::
+
+FsWatches::
+
+FsWatchesRecursive::
+
+Info 2    [00:00:31.000] Search path: /src/projects/app
+Info 3    [00:00:32.000] For info: /src/projects/app/appB.ts :: Config file name: /src/projects/app/tsconfig.json
+Info 4    [00:00:33.000] Creating configuration project /src/projects/app/tsconfig.json
+Info 5    [00:00:34.000] FileWatcher:: Added:: WatchInfo: /src/projects/app/tsconfig.json 2000 undefined Project: /src/projects/app/tsconfig.json WatchType: Config file
+Info 6    [00:00:35.000] Config: /src/projects/app/tsconfig.json : {
+ "rootNames": [
+  "/src/projects/app/appA.ts",
+  "/src/projects/app/appB.ts"
+ ],
+ "options": {
+  "composite": true,
+  "traceResolution": true,
+  "configFilePath": "/src/projects/app/tsconfig.json"
+ },
+ "projectReferences": [
+  {
+   "path": "/src/projects/common",
+   "originalPath": "../common"
+  }
+ ]
+}
+Info 7    [00:00:36.000] DirectoryWatcher:: Added:: WatchInfo: /src/projects/app 1 undefined Config: /src/projects/app/tsconfig.json WatchType: Wild card directory
+Info 8    [00:00:37.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /src/projects/app 1 undefined Config: /src/projects/app/tsconfig.json WatchType: Wild card directory
+Info 9    [00:00:38.000] FileWatcher:: Added:: WatchInfo: /src/projects/app/appA.ts 500 undefined WatchType: Closed Script info
+Info 10   [00:00:39.000] Starting updateGraphWorker: Project: /src/projects/app/tsconfig.json
+Info 11   [00:00:40.000] Config: /src/projects/common/tsconfig.json : {
+ "rootNames": [
+  "/src/projects/common/moduleA.ts",
+  "/src/projects/common/moduleB.ts"
+ ],
+ "options": {
+  "composite": true,
+  "traceResolution": true,
+  "configFilePath": "/src/projects/common/tsconfig.json"
+ }
+}
+Info 12   [00:00:41.000] FileWatcher:: Added:: WatchInfo: /src/projects/common/tsconfig.json 2000 undefined Project: /src/projects/app/tsconfig.json WatchType: Config file
+Info 13   [00:00:42.000] DirectoryWatcher:: Added:: WatchInfo: /src/projects/common 1 undefined Config: /src/projects/common/tsconfig.json WatchType: Wild card directory
+Info 14   [00:00:43.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /src/projects/common 1 undefined Config: /src/projects/common/tsconfig.json WatchType: Wild card directory
+Info 15   [00:00:44.000] ======== Resolving module 'moduleX' from '/src/projects/app/appA.ts'. ========
+Info 16   [00:00:45.000] Module resolution kind is not specified, using 'NodeJs'.
+Info 17   [00:00:46.000] Loading module 'moduleX' from 'node_modules' folder, target file types: TypeScript, Declaration.
+Info 18   [00:00:47.000] Directory '/src/projects/app/node_modules' does not exist, skipping all lookups in it.
+Info 19   [00:00:48.000] File '/src/projects/node_modules/moduleX/package.json' does not exist.
+Info 20   [00:00:49.000] File '/src/projects/node_modules/moduleX.ts' does not exist.
+Info 21   [00:00:50.000] File '/src/projects/node_modules/moduleX.tsx' does not exist.
+Info 22   [00:00:51.000] File '/src/projects/node_modules/moduleX.d.ts' does not exist.
+Info 23   [00:00:52.000] File '/src/projects/node_modules/moduleX/index.ts' does not exist.
+Info 24   [00:00:53.000] File '/src/projects/node_modules/moduleX/index.tsx' does not exist.
+Info 25   [00:00:54.000] File '/src/projects/node_modules/moduleX/index.d.ts' exist - use it as a name resolution result.
+Info 26   [00:00:55.000] Resolving real path for '/src/projects/node_modules/moduleX/index.d.ts', result '/src/projects/node_modules/moduleX/index.d.ts'.
+Info 27   [00:00:56.000] ======== Module name 'moduleX' was successfully resolved to '/src/projects/node_modules/moduleX/index.d.ts'. ========
+Info 28   [00:00:57.000] DirectoryWatcher:: Added:: WatchInfo: /src/projects/node_modules 1 undefined WatchType: node_modules for closed script infos and package.jsons affecting module specifier cache
+Info 29   [00:00:58.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /src/projects/node_modules 1 undefined WatchType: node_modules for closed script infos and package.jsons affecting module specifier cache
+Info 30   [00:00:59.000] ======== Resolving module '../common/moduleB' from '/src/projects/app/appB.ts'. ========
+Info 31   [00:01:00.000] Module resolution kind is not specified, using 'NodeJs'.
+Info 32   [00:01:01.000] Loading module as file / folder, candidate module location '/src/projects/common/moduleB', target file types: TypeScript, Declaration.
+Info 33   [00:01:02.000] File '/src/projects/common/moduleB.ts' exist - use it as a name resolution result.
+Info 34   [00:01:03.000] ======== Module name '../common/moduleB' was successfully resolved to '/src/projects/common/moduleB.ts'. ========
+Info 35   [00:01:04.000] FileWatcher:: Added:: WatchInfo: /src/projects/common/moduleB.ts 500 undefined WatchType: Closed Script info
+Info 36   [00:01:05.000] ======== Resolving module 'moduleX' from '/src/projects/common/moduleB.ts'. ========
+Info 37   [00:01:06.000] Using compiler options of project reference redirect '/src/projects/common/tsconfig.json'.
+Info 38   [00:01:07.000] Module resolution kind is not specified, using 'NodeJs'.
+Info 39   [00:01:08.000] Loading module 'moduleX' from 'node_modules' folder, target file types: TypeScript, Declaration.
+Info 40   [00:01:09.000] Directory '/src/projects/common/node_modules' does not exist, skipping all lookups in it.
+Info 41   [00:01:10.000] Resolution for module 'moduleX' was found in cache from location '/src/projects'.
+Info 42   [00:01:11.000] ======== Module name 'moduleX' was successfully resolved to '/src/projects/node_modules/moduleX/index.d.ts'. ========
+Info 43   [00:01:12.000] DirectoryWatcher:: Added:: WatchInfo: /src/projects/app/node_modules 1 undefined Project: /src/projects/app/tsconfig.json WatchType: Failed Lookup Locations
+Info 44   [00:01:13.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /src/projects/app/node_modules 1 undefined Project: /src/projects/app/tsconfig.json WatchType: Failed Lookup Locations
+Info 45   [00:01:14.000] FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined Project: /src/projects/app/tsconfig.json WatchType: Missing file
+Info 46   [00:01:15.000] DirectoryWatcher:: Added:: WatchInfo: /src/projects/app/node_modules/@types 1 undefined Project: /src/projects/app/tsconfig.json WatchType: Type roots
+Info 47   [00:01:16.000] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /src/projects/app/node_modules/@types 1 undefined Project: /src/projects/app/tsconfig.json WatchType: Type roots
+Info 48   [00:01:17.000] Finishing updateGraphWorker: Project: /src/projects/app/tsconfig.json Version: 1 structureChanged: true structureIsReused:: Not Elapsed:: *ms
+Info 49   [00:01:18.000] Project '/src/projects/app/tsconfig.json' (Configured)
+Info 50   [00:01:19.000] 	Files (4)
+	/src/projects/node_modules/moduleX/index.d.ts
+	/src/projects/app/appA.ts
+	/src/projects/common/moduleB.ts
+	/src/projects/app/appB.ts
+
+
+	../node_modules/moduleX/index.d.ts
+	  Imported via "moduleX" from file 'appA.ts'
+	  Imported via "moduleX" from file '../common/moduleB.ts'
+	appA.ts
+	  Matched by default include pattern '**/*'
+	../common/moduleB.ts
+	  Imported via "../common/moduleB" from file 'appB.ts'
+	appB.ts
+	  Matched by default include pattern '**/*'
+
+Info 51   [00:01:20.000] -----------------------------------------------
+Info 52   [00:01:21.000] Search path: /src/projects/app
+Info 53   [00:01:22.000] For info: /src/projects/app/tsconfig.json :: No config files found.
+Info 54   [00:01:23.000] Project '/src/projects/app/tsconfig.json' (Configured)
+Info 54   [00:01:24.000] 	Files (4)
+
+Info 54   [00:01:25.000] -----------------------------------------------
+Info 54   [00:01:26.000] Open files: 
+Info 54   [00:01:27.000] 	FileName: /src/projects/app/appB.ts ProjectRootPath: undefined
+Info 54   [00:01:28.000] 		Projects: /src/projects/app/tsconfig.json
+After request
+
+PolledWatches::
+/src/projects/app/node_modules:
+  {"pollingInterval":500}
+/a/lib/lib.d.ts:
+  {"pollingInterval":500}
+/src/projects/app/node_modules/@types:
+  {"pollingInterval":500}
+
+FsWatches::
+/src/projects/app/tsconfig.json:
+  {}
+/src/projects/app/appa.ts:
+  {}
+/src/projects/common/tsconfig.json:
+  {}
+/src/projects/common/moduleb.ts:
+  {}
+
+FsWatchesRecursive::
+/src/projects/app:
+  {}
+/src/projects/common:
+  {}
+/src/projects/node_modules:
+  {}
+
+Info 54   [00:01:29.000] response:
+    {
+      "responseRequired": false
+    }