Merge

src/services/breakpoints.ts

@@ -722,5 +722,5 @@ namespace ts.BreakpointResolver {
                 return spanInNode(node.parent);
             }
         }
-   }
+    }
 }

src/services/navigationBar.ts

@@ -188,7 +188,10 @@ namespace ts.NavigationBar {
                     case SyntaxKind.ModuleDeclaration:
                         let moduleDeclaration = <ModuleDeclaration>node;
                         topLevelNodes.push(node);
-                        addTopLevelNodes((<Block>getInnermostModule(moduleDeclaration).body).statements, topLevelNodes);
+                        const inner = getInnermostModule(moduleDeclaration);
+                        if (inner.body) {
+                            addTopLevelNodes((<Block>inner.body).statements, topLevelNodes);
+                        }
                         break;
 
                     case SyntaxKind.FunctionDeclaration:
@@ -453,7 +456,8 @@ namespace ts.NavigationBar {
             function createModuleItem(node: ModuleDeclaration): NavigationBarItem {
                 const moduleName = getModuleName(node);
 
-                const childItems = getItemsWorker(getChildNodes((<Block>getInnermostModule(node).body).statements), createChildItem);
+                const body = <Block>getInnermostModule(node).body;
+                const childItems = body ? getItemsWorker(getChildNodes(body.statements), createChildItem) : [];
 
                 return getNavigationBarItem(moduleName,
                     ts.ScriptElementKind.moduleElement,
@@ -611,7 +615,7 @@ namespace ts.NavigationBar {
         }
 
         function getInnermostModule(node: ModuleDeclaration): ModuleDeclaration {
-            while (node.body.kind === SyntaxKind.ModuleDeclaration) {
+            while (node.body && node.body.kind === SyntaxKind.ModuleDeclaration) {
                 node = <ModuleDeclaration>node.body;
             }
 

src/services/services.ts

@@ -406,37 +406,56 @@ namespace ts {
                     const sourceFileOfDeclaration = getSourceFileOfNode(declaration);
                     // If it is parameter - try and get the jsDoc comment with @param tag from function declaration's jsDoc comments
                     if (canUseParsedParamTagComments && declaration.kind === SyntaxKind.Parameter) {
-                        ts.forEach(getJsDocCommentTextRange(declaration.parent, sourceFileOfDeclaration), jsDocCommentTextRange => {
-                            const cleanedParamJsDocComment = getCleanedParamJsDocComment(jsDocCommentTextRange.pos, jsDocCommentTextRange.end, sourceFileOfDeclaration);
-                            if (cleanedParamJsDocComment) {
-                                addRange(jsDocCommentParts, cleanedParamJsDocComment);
-                            }
-                        });
+                        if ((declaration.parent.kind === SyntaxKind.FunctionExpression || declaration.parent.kind === SyntaxKind.ArrowFunction) &&
+                            declaration.parent.parent.kind === SyntaxKind.VariableDeclaration) {
+                            addCommentParts(declaration.parent.parent.parent, sourceFileOfDeclaration, getCleanedParamJsDocComment);
+                        }
+                        addCommentParts(declaration.parent, sourceFileOfDeclaration, getCleanedParamJsDocComment);
                     }
 
                     // If this is left side of dotted module declaration, there is no doc comments associated with this node
-                    if (declaration.kind === SyntaxKind.ModuleDeclaration && (<ModuleDeclaration>declaration).body.kind === SyntaxKind.ModuleDeclaration) {
+                    if (declaration.kind === SyntaxKind.ModuleDeclaration && (<ModuleDeclaration>declaration).body && (<ModuleDeclaration>declaration).body.kind === SyntaxKind.ModuleDeclaration) {
                         return;
                     }
 
+                    if ((declaration.kind === SyntaxKind.FunctionExpression || declaration.kind === SyntaxKind.ArrowFunction) &&
+                        declaration.parent.kind === SyntaxKind.VariableDeclaration) {
+                        addCommentParts(declaration.parent.parent, sourceFileOfDeclaration, getCleanedJsDocComment);
+                    }
+
                     // If this is dotted module name, get the doc comments from the parent
                     while (declaration.kind === SyntaxKind.ModuleDeclaration && declaration.parent.kind === SyntaxKind.ModuleDeclaration) {
                         declaration = <ModuleDeclaration>declaration.parent;
                     }
+                    addCommentParts(declaration.kind === SyntaxKind.VariableDeclaration ? declaration.parent.parent : declaration,
+                                    sourceFileOfDeclaration,
+                                    getCleanedJsDocComment);
 
-                    // Get the cleaned js doc comment text from the declaration
-                    ts.forEach(getJsDocCommentTextRange(
-                        declaration.kind === SyntaxKind.VariableDeclaration ? declaration.parent.parent : declaration, sourceFileOfDeclaration), jsDocCommentTextRange => {
-                            const cleanedJsDocComment = getCleanedJsDocComment(jsDocCommentTextRange.pos, jsDocCommentTextRange.end, sourceFileOfDeclaration);
-                            if (cleanedJsDocComment) {
-                                addRange(jsDocCommentParts, cleanedJsDocComment);
-                            }
-                        });
+                    if (declaration.kind === SyntaxKind.VariableDeclaration) {
+                        const init = (declaration as VariableDeclaration).initializer;
+                        if (init && (init.kind === SyntaxKind.FunctionExpression || init.kind === SyntaxKind.ArrowFunction)) {
+                            // Get the cleaned js doc comment text from the initializer
+                            addCommentParts(init, sourceFileOfDeclaration, getCleanedJsDocComment);
+                        }
+                    }
                 }
             });
 
             return jsDocCommentParts;
 
+            function addCommentParts(commented: Node,
+                                     sourceFileOfDeclaration: SourceFile,
+                                     getCommentPart: (pos: number, end: number, file: SourceFile) => SymbolDisplayPart[]): void {
+                const ranges = getJsDocCommentTextRange(commented, sourceFileOfDeclaration);
+                // Get the cleaned js doc comment text from the declaration
+                ts.forEach(ranges, jsDocCommentTextRange => {
+                    const cleanedComment = getCommentPart(jsDocCommentTextRange.pos, jsDocCommentTextRange.end, sourceFileOfDeclaration);
+                    if (cleanedComment) {
+                        addRange(jsDocCommentParts, cleanedComment);
+                    }
+                });
+            }
+
             function getJsDocCommentTextRange(node: Node, sourceFile: SourceFile): TextRange[] {
                 return ts.map(getJsDocComments(node, sourceFile),
                     jsDocComment => {
@@ -1045,10 +1064,10 @@ namespace ts {
         getCancellationToken?(): HostCancellationToken;
         getCurrentDirectory(): string;
         getDefaultLibFileName(options: CompilerOptions): string;
-        log? (s: string): void;
-        trace? (s: string): void;
-        error? (s: string): void;
-        useCaseSensitiveFileNames? (): boolean;
+        log?(s: string): void;
+        trace?(s: string): void;
+        error?(s: string): void;
+        useCaseSensitiveFileNames?(): boolean;
 
         /*
          * LS host can optionally implement this method if it wants to be completely in charge of module name resolution.
@@ -1921,6 +1940,40 @@ namespace ts {
         sourceMapText?: string;
     }
 
+
+
+    let commandLineOptions_stringToEnum: CommandLineOptionOfCustomType[];
+
+    /** JS users may pass in string values for enum compiler options (such as ModuleKind), so convert. */
+    function fixupCompilerOptions(options: CompilerOptions, diagnostics: Diagnostic[]): CompilerOptions {
+        // Lazily create this value to fix module loading errors.
+        commandLineOptions_stringToEnum = commandLineOptions_stringToEnum || <CommandLineOptionOfCustomType[]>filter(optionDeclarations, o =>
+            typeof o.type === "object" && !forEachValue(<Map<any>> o.type, v => typeof v !== "number"));
+
+        options = clone(options);
+
+        for (const opt of commandLineOptions_stringToEnum) {
+            if (!hasProperty(options, opt.name)) {
+                continue;
+            }
+
+            const value = options[opt.name];
+            // Value should be a key of opt.type
+            if (typeof value === "string") {
+                // If value is not a string, this will fail
+                options[opt.name] = parseCustomTypeOption(opt, value, diagnostics);
+            }
+            else {
+                if (!forEachValue(opt.type, v => v === value)) {
+                    // Supplied value isn't a valid enum value.
+                    diagnostics.push(createCompilerDiagnosticForInvalidCustomType(opt));
+                }
+            }
+        }
+
+        return options;
+    }
+
     /*
      * This function will compile source text from 'input' argument using specified compiler options.
      * If not options are provided - it will use a set of default compiler options.
@@ -1931,7 +1984,9 @@ namespace ts {
      * - noResolve = true
      */
     export function transpileModule(input: string, transpileOptions: TranspileOptions): TranspileOutput {
-        const options = transpileOptions.compilerOptions ? clone(transpileOptions.compilerOptions) : getDefaultCompilerOptions();
+        const diagnostics: Diagnostic[] = [];
+
+        const options: CompilerOptions = transpileOptions.compilerOptions ? fixupCompilerOptions(transpileOptions.compilerOptions, diagnostics) : getDefaultCompilerOptions();
 
         options.isolatedModules = true;
 
@@ -1990,9 +2045,7 @@ namespace ts {
 
         const program = createProgram([inputFileName], options, compilerHost);
 
-        let diagnostics: Diagnostic[];
         if (transpileOptions.reportDiagnostics) {
-            diagnostics = [];
             addRange(/*to*/ diagnostics, /*from*/ program.getSyntacticDiagnostics(sourceFile));
             addRange(/*to*/ diagnostics, /*from*/ program.getOptionsDiagnostics());
         }
@@ -2482,7 +2535,7 @@ namespace ts {
                 }
 
                 // should be start of dependency list
-                if (token !== SyntaxKind.OpenBracketToken)  {
+                if (token !== SyntaxKind.OpenBracketToken) {
                     return true;
                 }
 
@@ -2921,6 +2974,7 @@ namespace ts {
             const changesInCompilationSettingsAffectSyntax = oldSettings &&
                 (oldSettings.target !== newSettings.target ||
                  oldSettings.module !== newSettings.module ||
+                 oldSettings.moduleResolution !== newSettings.moduleResolution ||
                  oldSettings.noResolve !== newSettings.noResolve ||
                  oldSettings.jsx !== newSettings.jsx ||
                  oldSettings.allowJs !== newSettings.allowJs);
@@ -4016,10 +4070,15 @@ namespace ts {
             }
         }
 
-
         function getCompletionsAtPosition(fileName: string, position: number): CompletionInfo {
             synchronizeHostData();
 
+            const sourceFile = getValidSourceFile(fileName);
+
+            if (isInString(sourceFile, position)) {
+                return getStringLiteralCompletionEntries(sourceFile, position);
+            }
+
             const completionData = getCompletionData(fileName, position);
             if (!completionData) {
                 return undefined;
@@ -4032,12 +4091,10 @@ namespace ts {
                 return { isMemberCompletion: false, isNewIdentifierLocation: false, entries: getAllJsDocCompletionEntries() };
             }
 
-            const sourceFile = getValidSourceFile(fileName);
-
             const entries: CompletionEntry[] = [];
 
             if (isSourceFileJavaScript(sourceFile)) {
-                const uniqueNames = getCompletionEntriesFromSymbols(symbols, entries);
+                const uniqueNames = getCompletionEntriesFromSymbols(symbols, entries, location, /*performCharacterChecks*/ false);
                 addRange(entries, getJavaScriptCompletionEntries(sourceFile, location.pos, uniqueNames));
             }
             else {
@@ -4061,7 +4118,7 @@ namespace ts {
                     }
                 }
 
-                getCompletionEntriesFromSymbols(symbols, entries);
+                getCompletionEntriesFromSymbols(symbols, entries, location, /*performCharacterChecks*/ true);
             }
 
             // Add keywords if this is not a member completion list
@@ -4111,11 +4168,11 @@ namespace ts {
                 }));
             }
 
-            function createCompletionEntry(symbol: Symbol, location: Node): CompletionEntry {
+            function createCompletionEntry(symbol: Symbol, location: Node, performCharacterChecks: boolean): CompletionEntry {
                 // Try to get a valid display name for this symbol, if we could not find one, then ignore it.
                 // We would like to only show things that can be added after a dot, so for instance numeric properties can
                 // not be accessed with a dot (a.1 <- invalid)
-                const displayName = getCompletionEntryDisplayNameForSymbol(symbol, program.getCompilerOptions().target, /*performCharacterChecks*/ true, location);
+                const displayName = getCompletionEntryDisplayNameForSymbol(symbol, program.getCompilerOptions().target, performCharacterChecks, location);
                 if (!displayName) {
                     return undefined;
                 }
@@ -4136,12 +4193,12 @@ namespace ts {
                 };
             }
 
-            function getCompletionEntriesFromSymbols(symbols: Symbol[], entries: CompletionEntry[]): Map<string> {
+            function getCompletionEntriesFromSymbols(symbols: Symbol[], entries: CompletionEntry[], location: Node, performCharacterChecks: boolean): Map<string> {
                 const start = new Date().getTime();
                 const uniqueNames: Map<string> = {};
                 if (symbols) {
                     for (const symbol of symbols) {
-                        const entry = createCompletionEntry(symbol, location);
+                        const entry = createCompletionEntry(symbol, location, performCharacterChecks);
                         if (entry) {
                             const id = escapeIdentifier(entry.name);
                             if (!lookUp(uniqueNames, id)) {
@@ -4155,6 +4212,93 @@ namespace ts {
                 log("getCompletionsAtPosition: getCompletionEntriesFromSymbols: " + (new Date().getTime() - start));
                 return uniqueNames;
             }
+
+            function getStringLiteralCompletionEntries(sourceFile: SourceFile, position: number) {
+                const node = findPrecedingToken(position, sourceFile);
+                if (!node || node.kind !== SyntaxKind.StringLiteral) {
+                    return undefined;
+                }
+
+                const argumentInfo = SignatureHelp.getContainingArgumentInfo(node, position, sourceFile);
+                if (argumentInfo) {
+                    // Get string literal completions from specialized signatures of the target
+                    return getStringLiteralCompletionEntriesFromCallExpression(argumentInfo);
+                }
+                else if (isElementAccessExpression(node.parent) && node.parent.argumentExpression === node) {
+                    // Get all names of properties on the expression
+                    return getStringLiteralCompletionEntriesFromElementAccess(node.parent);
+                }
+                else {
+                    // Otherwise, get the completions from the contextual type if one exists
+                    return getStringLiteralCompletionEntriesFromContextualType(<StringLiteral>node);
+                }
+            }
+
+            function getStringLiteralCompletionEntriesFromCallExpression(argumentInfo: SignatureHelp.ArgumentListInfo) {
+                const typeChecker = program.getTypeChecker();
+                const candidates: Signature[] = [];
+                const entries: CompletionEntry[] = [];
+
+                typeChecker.getResolvedSignature(argumentInfo.invocation, candidates);
+
+                for (const candidate of candidates) {
+                    if (candidate.parameters.length > argumentInfo.argumentIndex) {
+                        const parameter = candidate.parameters[argumentInfo.argumentIndex];
+                        addStringLiteralCompletionsFromType(typeChecker.getTypeAtLocation(parameter.valueDeclaration), entries);
+                    }
+                }
+
+                if (entries.length) {
+                    return { isMemberCompletion: false, isNewIdentifierLocation: true, entries };
+                }
+
+                return undefined;
+            }
+
+            function getStringLiteralCompletionEntriesFromElementAccess(node: ElementAccessExpression) {
+                const typeChecker = program.getTypeChecker();
+                const type = typeChecker.getTypeAtLocation(node.expression);
+                const entries: CompletionEntry[] = [];
+                if (type) {
+                    getCompletionEntriesFromSymbols(type.getApparentProperties(), entries, node, /*performCharacterChecks*/false);
+                    if (entries.length) {
+                        return { isMemberCompletion: true, isNewIdentifierLocation: true, entries };
+                    }
+                }
+                return undefined;
+            }
+
+            function getStringLiteralCompletionEntriesFromContextualType(node: StringLiteral) {
+                const typeChecker = program.getTypeChecker();
+                const type = typeChecker.getContextualType(node);
+                if (type) {
+                    const entries: CompletionEntry[] = [];
+                    addStringLiteralCompletionsFromType(type, entries);
+                    if (entries.length) {
+                        return { isMemberCompletion: false, isNewIdentifierLocation: false, entries };
+                    }
+                }
+                return undefined;
+            }
+
+            function addStringLiteralCompletionsFromType(type: Type, result: CompletionEntry[]): void {
+                if (!type) {
+                    return;
+                }
+                if (type.flags & TypeFlags.Union) {
+                    forEach((<UnionType>type).types, t => addStringLiteralCompletionsFromType(t, result));
+                }
+                else {
+                    if (type.flags & TypeFlags.StringLiteral) {
+                        result.push({
+                            name: (<StringLiteralType>type).text,
+                            kindModifiers: ScriptElementKindModifier.none,
+                            kind: ScriptElementKind.variableElement,
+                            sortText: "0"
+                        });
+                    }
+                }
+            }
         }
 
         function getCompletionEntryDetails(fileName: string, position: number, entryName: string): CompletionEntryDetails {
@@ -4319,7 +4463,7 @@ namespace ts {
                     // try get the call/construct signature from the type if it matches
                     let callExpression: CallExpression;
                     if (location.kind === SyntaxKind.CallExpression || location.kind === SyntaxKind.NewExpression) {
-                        callExpression = <CallExpression> location;
+                        callExpression = <CallExpression>location;
                     }
                     else if (isCallExpressionTarget(location) || isNewExpressionTarget(location)) {
                         callExpression = <CallExpression>location.parent;

src/services/signatureHelp.ts

@@ -162,15 +162,16 @@ namespace ts.SignatureHelp {
     //    // Did not find matching token
     //    return null;
     // }
+
     const emptyArray: any[] = [];
 
-    const enum ArgumentListKind {
+    export const enum ArgumentListKind {
         TypeArguments,
         CallArguments,
         TaggedTemplateArguments
     }
 
-    interface ArgumentListInfo {
+    export interface ArgumentListInfo {
         kind: ArgumentListKind;
         invocation: CallLikeExpression;
         argumentsSpan: TextSpan;
@@ -188,7 +189,8 @@ namespace ts.SignatureHelp {
             return undefined;
         }
 
-        const argumentInfo = getContainingArgumentInfo(startingToken);
+        const argumentInfo = getContainingArgumentInfo(startingToken, position, sourceFile);
+
         cancellationToken.throwIfCancellationRequested();
 
         // Semantic filtering of signature help
@@ -205,431 +207,432 @@ namespace ts.SignatureHelp {
             // We didn't have any sig help items produced by the TS compiler.  If this is a JS
             // file, then see if we can figure out anything better.
             if (isSourceFileJavaScript(sourceFile)) {
-                return createJavaScriptSignatureHelpItems(argumentInfo);
+                return createJavaScriptSignatureHelpItems(argumentInfo, program);
             }
 
             return undefined;
         }
 
-        return createSignatureHelpItems(candidates, resolvedSignature, argumentInfo);
+        return createSignatureHelpItems(candidates, resolvedSignature, argumentInfo, typeChecker);
+    }
 
-        function createJavaScriptSignatureHelpItems(argumentInfo: ArgumentListInfo): SignatureHelpItems {
-            if (argumentInfo.invocation.kind !== SyntaxKind.CallExpression) {
-                return undefined;
-            }
+    function createJavaScriptSignatureHelpItems(argumentInfo: ArgumentListInfo, program: Program): SignatureHelpItems {
+        if (argumentInfo.invocation.kind !== SyntaxKind.CallExpression) {
+            return undefined;
+        }
 
-            // See if we can find some symbol with the call expression name that has call signatures.
-            const callExpression = <CallExpression>argumentInfo.invocation;
-            const expression = callExpression.expression;
-            const name = expression.kind === SyntaxKind.Identifier
-                ? <Identifier> expression
-                : expression.kind === SyntaxKind.PropertyAccessExpression
-                    ? (<PropertyAccessExpression>expression).name
-                    : undefined;
+        // See if we can find some symbol with the call expression name that has call signatures.
+        const callExpression = <CallExpression>argumentInfo.invocation;
+        const expression = callExpression.expression;
+        const name = expression.kind === SyntaxKind.Identifier
+            ? <Identifier>expression
+            : expression.kind === SyntaxKind.PropertyAccessExpression
+                ? (<PropertyAccessExpression>expression).name
+                : undefined;
 
-            if (!name || !name.text) {
-                return undefined;
-            }
+        if (!name || !name.text) {
+            return undefined;
+        }
 
-            const typeChecker = program.getTypeChecker();
-            for (const sourceFile of program.getSourceFiles()) {
-                const nameToDeclarations = sourceFile.getNamedDeclarations();
-                const declarations = getProperty(nameToDeclarations, name.text);
+        const typeChecker = program.getTypeChecker();
+        for (const sourceFile of program.getSourceFiles()) {
+            const nameToDeclarations = sourceFile.getNamedDeclarations();
+            const declarations = getProperty(nameToDeclarations, name.text);
 
-                if (declarations) {
-                    for (const declaration of declarations) {
-                        const symbol = declaration.symbol;
-                        if (symbol) {
-                            const type = typeChecker.getTypeOfSymbolAtLocation(symbol, declaration);
-                            if (type) {
-                                const callSignatures = type.getCallSignatures();
-                                if (callSignatures && callSignatures.length) {
-                                    return createSignatureHelpItems(callSignatures, callSignatures[0], argumentInfo);
-                                }
+            if (declarations) {
+                for (const declaration of declarations) {
+                    const symbol = declaration.symbol;
+                    if (symbol) {
+                        const type = typeChecker.getTypeOfSymbolAtLocation(symbol, declaration);
+                        if (type) {
+                            const callSignatures = type.getCallSignatures();
+                            if (callSignatures && callSignatures.length) {
+                                return createSignatureHelpItems(callSignatures, callSignatures[0], argumentInfo, typeChecker);
                             }
                         }
                     }
                 }
             }
         }
+    }
 
-        /**
-         * Returns relevant information for the argument list and the current argument if we are
-         * in the argument of an invocation; returns undefined otherwise.
-         */
-        function getImmediatelyContainingArgumentInfo(node: Node): ArgumentListInfo {
-            if (node.parent.kind === SyntaxKind.CallExpression || node.parent.kind === SyntaxKind.NewExpression) {
-                const callExpression = <CallExpression>node.parent;
-                // There are 3 cases to handle:
-                //   1. The token introduces a list, and should begin a sig help session
-                //   2. The token is either not associated with a list, or ends a list, so the session should end
-                //   3. The token is buried inside a list, and should give sig help
-                //
-                // The following are examples of each:
-                //
-                //    Case 1:
-                //          foo<#T, U>(#a, b)    -> The token introduces a list, and should begin a sig help session
-                //    Case 2:
-                //          fo#o<T, U>#(a, b)#   -> The token is either not associated with a list, or ends a list, so the session should end
-                //    Case 3:
-                //          foo<T#, U#>(a#, #b#) -> The token is buried inside a list, and should give sig help
-                // Find out if 'node' is an argument, a type argument, or neither
-                if (node.kind === SyntaxKind.LessThanToken ||
-                    node.kind === SyntaxKind.OpenParenToken) {
-                    // Find the list that starts right *after* the < or ( token.
-                    // If the user has just opened a list, consider this item 0.
-                    const list = getChildListThatStartsWithOpenerToken(callExpression, node, sourceFile);
-                    const isTypeArgList = callExpression.typeArguments && callExpression.typeArguments.pos === list.pos;
-                    Debug.assert(list !== undefined);
-                    return {
-                        kind: isTypeArgList ? ArgumentListKind.TypeArguments : ArgumentListKind.CallArguments,
-                        invocation: callExpression,
-                        argumentsSpan: getApplicableSpanForArguments(list),
-                        argumentIndex: 0,
-                        argumentCount: getArgumentCount(list)
-                    };
-                }
-
-                // findListItemInfo can return undefined if we are not in parent's argument list
-                // or type argument list. This includes cases where the cursor is:
-                //   - To the right of the closing paren, non-substitution template, or template tail.
-                //   - Between the type arguments and the arguments (greater than token)
-                //   - On the target of the call (parent.func)
-                //   - On the 'new' keyword in a 'new' expression
-                const listItemInfo = findListItemInfo(node);
-                if (listItemInfo) {
-                    const list = listItemInfo.list;
-                    const isTypeArgList = callExpression.typeArguments && callExpression.typeArguments.pos === list.pos;
-
-                    const argumentIndex = getArgumentIndex(list, node);
-                    const argumentCount = getArgumentCount(list);
-
-                    Debug.assert(argumentIndex === 0 || argumentIndex < argumentCount,
-                        `argumentCount < argumentIndex, ${argumentCount} < ${argumentIndex}`);
-
-                    return {
-                        kind: isTypeArgList ? ArgumentListKind.TypeArguments : ArgumentListKind.CallArguments,
-                        invocation: callExpression,
-                        argumentsSpan: getApplicableSpanForArguments(list),
-                        argumentIndex: argumentIndex,
-                        argumentCount: argumentCount
-                    };
-                }
-            }
-            else if (node.kind === SyntaxKind.NoSubstitutionTemplateLiteral && node.parent.kind === SyntaxKind.TaggedTemplateExpression) {
-                // Check if we're actually inside the template;
-                // otherwise we'll fall out and return undefined.
-                if (isInsideTemplateLiteral(<LiteralExpression>node, position)) {
-                    return getArgumentListInfoForTemplate(<TaggedTemplateExpression>node.parent, /*argumentIndex*/ 0);
-                }
-            }
-            else if (node.kind === SyntaxKind.TemplateHead && node.parent.parent.kind === SyntaxKind.TaggedTemplateExpression) {
-                const templateExpression = <TemplateExpression>node.parent;
-                const tagExpression = <TaggedTemplateExpression>templateExpression.parent;
-                Debug.assert(templateExpression.kind === SyntaxKind.TemplateExpression);
-
-                const argumentIndex = isInsideTemplateLiteral(<LiteralExpression>node, position) ? 0 : 1;
-
-                return getArgumentListInfoForTemplate(tagExpression, argumentIndex);
-            }
-            else if (node.parent.kind === SyntaxKind.TemplateSpan && node.parent.parent.parent.kind === SyntaxKind.TaggedTemplateExpression) {
-                const templateSpan = <TemplateSpan>node.parent;
-                const templateExpression = <TemplateExpression>templateSpan.parent;
-                const tagExpression = <TaggedTemplateExpression>templateExpression.parent;
-                Debug.assert(templateExpression.kind === SyntaxKind.TemplateExpression);
-
-                // If we're just after a template tail, don't show signature help.
-                if (node.kind === SyntaxKind.TemplateTail && !isInsideTemplateLiteral(<LiteralExpression>node, position)) {
-                    return undefined;
-                }
-
-                const spanIndex = templateExpression.templateSpans.indexOf(templateSpan);
-                const argumentIndex = getArgumentIndexForTemplatePiece(spanIndex, node);
-
-                return getArgumentListInfoForTemplate(tagExpression, argumentIndex);
-            }
-
-            return undefined;
-        }
-
-        function getArgumentIndex(argumentsList: Node, node: Node) {
-            // The list we got back can include commas.  In the presence of errors it may
-            // also just have nodes without commas.  For example "Foo(a b c)" will have 3
-            // args without commas.   We want to find what index we're at.  So we count
-            // forward until we hit ourselves, only incrementing the index if it isn't a
-            // comma.
+    /**
+     * Returns relevant information for the argument list and the current argument if we are
+     * in the argument of an invocation; returns undefined otherwise.
+     */
+    function getImmediatelyContainingArgumentInfo(node: Node, position: number, sourceFile: SourceFile): ArgumentListInfo {
+        if (node.parent.kind === SyntaxKind.CallExpression || node.parent.kind === SyntaxKind.NewExpression) {
+            const callExpression = <CallExpression>node.parent;
+            // There are 3 cases to handle:
+            //   1. The token introduces a list, and should begin a sig help session
+            //   2. The token is either not associated with a list, or ends a list, so the session should end
+            //   3. The token is buried inside a list, and should give sig help
             //
-            // Note: the subtlety around trailing commas (in getArgumentCount) does not apply
-            // here.  That's because we're only walking forward until we hit the node we're
-            // on.  In that case, even if we're after the trailing comma, we'll still see
-            // that trailing comma in the list, and we'll have generated the appropriate
-            // arg index.
-            let argumentIndex = 0;
-            const listChildren = argumentsList.getChildren();
-            for (const child of listChildren) {
-                if (child === node) {
-                    break;
-                }
-                if (child.kind !== SyntaxKind.CommaToken) {
-                    argumentIndex++;
-                }
+            // The following are examples of each:
+            //
+            //    Case 1:
+            //          foo<#T, U>(#a, b)    -> The token introduces a list, and should begin a sig help session
+            //    Case 2:
+            //          fo#o<T, U>#(a, b)#   -> The token is either not associated with a list, or ends a list, so the session should end
+            //    Case 3:
+            //          foo<T#, U#>(a#, #b#) -> The token is buried inside a list, and should give sig help
+            // Find out if 'node' is an argument, a type argument, or neither
+            if (node.kind === SyntaxKind.LessThanToken ||
+                node.kind === SyntaxKind.OpenParenToken) {
+                // Find the list that starts right *after* the < or ( token.
+                // If the user has just opened a list, consider this item 0.
+                const list = getChildListThatStartsWithOpenerToken(callExpression, node, sourceFile);
+                const isTypeArgList = callExpression.typeArguments && callExpression.typeArguments.pos === list.pos;
+                Debug.assert(list !== undefined);
+                return {
+                    kind: isTypeArgList ? ArgumentListKind.TypeArguments : ArgumentListKind.CallArguments,
+                    invocation: callExpression,
+                    argumentsSpan: getApplicableSpanForArguments(list, sourceFile),
+                    argumentIndex: 0,
+                    argumentCount: getArgumentCount(list)
+                };
             }
 
-            return argumentIndex;
-        }
+            // findListItemInfo can return undefined if we are not in parent's argument list
+            // or type argument list. This includes cases where the cursor is:
+            //   - To the right of the closing paren, non-substitution template, or template tail.
+            //   - Between the type arguments and the arguments (greater than token)
+            //   - On the target of the call (parent.func)
+            //   - On the 'new' keyword in a 'new' expression
+            const listItemInfo = findListItemInfo(node);
+            if (listItemInfo) {
+                const list = listItemInfo.list;
+                const isTypeArgList = callExpression.typeArguments && callExpression.typeArguments.pos === list.pos;
 
-        function getArgumentCount(argumentsList: Node) {
-            // The argument count for a list is normally the number of non-comma children it has.
-            // For example, if you have "Foo(a,b)" then there will be three children of the arg
-            // list 'a' '<comma>' 'b'.  So, in this case the arg count will be 2.  However, there
-            // is a small subtlety.  If you have  "Foo(a,)", then the child list will just have
-            // 'a' '<comma>'.  So, in the case where the last child is a comma, we increase the
-            // arg count by one to compensate.
-            //
-            // Note: this subtlety only applies to the last comma.  If you had "Foo(a,,"  then
-            // we'll have:  'a' '<comma>' '<missing>'
-            // That will give us 2 non-commas.  We then add one for the last comma, givin us an
-            // arg count of 3.
-            const listChildren = argumentsList.getChildren();
+                const argumentIndex = getArgumentIndex(list, node);
+                const argumentCount = getArgumentCount(list);
 
-            let argumentCount = countWhere(listChildren, arg => arg.kind !== SyntaxKind.CommaToken);
-            if (listChildren.length > 0 && lastOrUndefined(listChildren).kind === SyntaxKind.CommaToken) {
-                argumentCount++;
-            }
+                Debug.assert(argumentIndex === 0 || argumentIndex < argumentCount,
+                    `argumentCount < argumentIndex, ${argumentCount} < ${argumentIndex}`);
 
-            return argumentCount;
-        }
-
-        // spanIndex is either the index for a given template span.
-        // This does not give appropriate results for a NoSubstitutionTemplateLiteral
-        function getArgumentIndexForTemplatePiece(spanIndex: number, node: Node): number {
-            // Because the TemplateStringsArray is the first argument, we have to offset each substitution expression by 1.
-            // There are three cases we can encounter:
-            //      1. We are precisely in the template literal (argIndex = 0).
-            //      2. We are in or to the right of the substitution expression (argIndex = spanIndex + 1).
-            //      3. We are directly to the right of the template literal, but because we look for the token on the left,
-            //          not enough to put us in the substitution expression; we should consider ourselves part of
-            //          the *next* span's expression by offsetting the index (argIndex = (spanIndex + 1) + 1).
-            //
-            // Example: f  `# abcd $#{#  1 + 1#  }# efghi ${ #"#hello"#  }  #  `
-            //              ^       ^ ^       ^   ^          ^ ^      ^     ^
-            // Case:        1       1 3       2   1          3 2      2     1
-            Debug.assert(position >= node.getStart(), "Assumed 'position' could not occur before node.");
-            if (isTemplateLiteralKind(node.kind)) {
-                if (isInsideTemplateLiteral(<LiteralExpression>node, position)) {
-                    return 0;
-                }
-                return spanIndex + 2;
-            }
-            return spanIndex + 1;
-        }
-
-        function getArgumentListInfoForTemplate(tagExpression: TaggedTemplateExpression, argumentIndex: number): ArgumentListInfo {
-            // argumentCount is either 1 or (numSpans + 1) to account for the template strings array argument.
-            const argumentCount = tagExpression.template.kind === SyntaxKind.NoSubstitutionTemplateLiteral
-                ? 1
-                : (<TemplateExpression>tagExpression.template).templateSpans.length + 1;
-
-            Debug.assert(argumentIndex === 0 || argumentIndex < argumentCount, `argumentCount < argumentIndex, ${argumentCount} < ${argumentIndex}`);
-
-            return {
-                kind: ArgumentListKind.TaggedTemplateArguments,
-                invocation: tagExpression,
-                argumentsSpan: getApplicableSpanForTaggedTemplate(tagExpression),
-                argumentIndex: argumentIndex,
-                argumentCount: argumentCount
-            };
-        }
-
-        function getApplicableSpanForArguments(argumentsList: Node): TextSpan {
-            // We use full start and skip trivia on the end because we want to include trivia on
-            // both sides. For example,
-            //
-            //    foo(   /*comment */     a, b, c      /*comment*/     )
-            //        |                                               |
-            //
-            // The applicable span is from the first bar to the second bar (inclusive,
-            // but not including parentheses)
-            const applicableSpanStart = argumentsList.getFullStart();
-            const applicableSpanEnd = skipTrivia(sourceFile.text, argumentsList.getEnd(), /*stopAfterLineBreak*/ false);
-            return createTextSpan(applicableSpanStart, applicableSpanEnd - applicableSpanStart);
-        }
-
-        function getApplicableSpanForTaggedTemplate(taggedTemplate: TaggedTemplateExpression): TextSpan {
-            const template = taggedTemplate.template;
-            const applicableSpanStart = template.getStart();
-            let applicableSpanEnd = template.getEnd();
-
-            // We need to adjust the end position for the case where the template does not have a tail.
-            // Otherwise, we will not show signature help past the expression.
-            // For example,
-            //
-            //      `  ${ 1 + 1        foo(10)
-            //       |        |
-            //
-            // This is because a Missing node has no width. However, what we actually want is to include trivia
-            // leading up to the next token in case the user is about to type in a TemplateMiddle or TemplateTail.
-            if (template.kind === SyntaxKind.TemplateExpression) {
-                const lastSpan = lastOrUndefined((<TemplateExpression>template).templateSpans);
-                if (lastSpan.literal.getFullWidth() === 0) {
-                    applicableSpanEnd = skipTrivia(sourceFile.text, applicableSpanEnd, /*stopAfterLineBreak*/ false);
-                }
-            }
-
-            return createTextSpan(applicableSpanStart, applicableSpanEnd - applicableSpanStart);
-        }
-
-        function getContainingArgumentInfo(node: Node): ArgumentListInfo {
-            for (let n = node; n.kind !== SyntaxKind.SourceFile; n = n.parent) {
-                if (isFunctionBlock(n)) {
-                    return undefined;
-                }
-
-                // If the node is not a subspan of its parent, this is a big problem.
-                // There have been crashes that might be caused by this violation.
-                if (n.pos < n.parent.pos || n.end > n.parent.end) {
-                    Debug.fail("Node of kind " + n.kind + " is not a subspan of its parent of kind " + n.parent.kind);
-                }
-
-                const argumentInfo = getImmediatelyContainingArgumentInfo(n);
-                if (argumentInfo) {
-                    return argumentInfo;
-                }
-
-
-                // TODO: Handle generic call with incomplete syntax
+                return {
+                    kind: isTypeArgList ? ArgumentListKind.TypeArguments : ArgumentListKind.CallArguments,
+                    invocation: callExpression,
+                    argumentsSpan: getApplicableSpanForArguments(list, sourceFile),
+                    argumentIndex: argumentIndex,
+                    argumentCount: argumentCount
+                };
             }
             return undefined;
         }
-
-        function getChildListThatStartsWithOpenerToken(parent: Node, openerToken: Node, sourceFile: SourceFile): Node {
-            const children = parent.getChildren(sourceFile);
-            const indexOfOpenerToken = children.indexOf(openerToken);
-            Debug.assert(indexOfOpenerToken >= 0 && children.length > indexOfOpenerToken + 1);
-            return children[indexOfOpenerToken + 1];
+        else if (node.kind === SyntaxKind.NoSubstitutionTemplateLiteral && node.parent.kind === SyntaxKind.TaggedTemplateExpression) {
+            // Check if we're actually inside the template;
+            // otherwise we'll fall out and return undefined.
+            if (isInsideTemplateLiteral(<LiteralExpression>node, position)) {
+                return getArgumentListInfoForTemplate(<TaggedTemplateExpression>node.parent, /*argumentIndex*/ 0, sourceFile);
+            }
         }
+        else if (node.kind === SyntaxKind.TemplateHead && node.parent.parent.kind === SyntaxKind.TaggedTemplateExpression) {
+            const templateExpression = <TemplateExpression>node.parent;
+            const tagExpression = <TaggedTemplateExpression>templateExpression.parent;
+            Debug.assert(templateExpression.kind === SyntaxKind.TemplateExpression);
 
-        /**
-         * The selectedItemIndex could be negative for several reasons.
-         *     1. There are too many arguments for all of the overloads
-         *     2. None of the overloads were type compatible
-         * The solution here is to try to pick the best overload by picking
-         * either the first one that has an appropriate number of parameters,
-         * or the one with the most parameters.
-         */
-        function selectBestInvalidOverloadIndex(candidates: Signature[], argumentCount: number): number {
-            let maxParamsSignatureIndex = -1;
-            let maxParams = -1;
-            for (let i = 0; i < candidates.length; i++) {
-                const candidate = candidates[i];
+            const argumentIndex = isInsideTemplateLiteral(<LiteralExpression>node, position) ? 0 : 1;
 
-                if (candidate.hasRestParameter || candidate.parameters.length >= argumentCount) {
-                    return i;
-                }
+            return getArgumentListInfoForTemplate(tagExpression, argumentIndex, sourceFile);
+        }
+        else if (node.parent.kind === SyntaxKind.TemplateSpan && node.parent.parent.parent.kind === SyntaxKind.TaggedTemplateExpression) {
+            const templateSpan = <TemplateSpan>node.parent;
+            const templateExpression = <TemplateExpression>templateSpan.parent;
+            const tagExpression = <TaggedTemplateExpression>templateExpression.parent;
+            Debug.assert(templateExpression.kind === SyntaxKind.TemplateExpression);
 
-                if (candidate.parameters.length > maxParams) {
-                    maxParams = candidate.parameters.length;
-                    maxParamsSignatureIndex = i;
-                }
+            // If we're just after a template tail, don't show signature help.
+            if (node.kind === SyntaxKind.TemplateTail && !isInsideTemplateLiteral(<LiteralExpression>node, position)) {
+                return undefined;
             }
 
-            return maxParamsSignatureIndex;
+            const spanIndex = templateExpression.templateSpans.indexOf(templateSpan);
+            const argumentIndex = getArgumentIndexForTemplatePiece(spanIndex, node, position);
+
+            return getArgumentListInfoForTemplate(tagExpression, argumentIndex, sourceFile);
         }
 
-        function createSignatureHelpItems(candidates: Signature[], bestSignature: Signature, argumentListInfo: ArgumentListInfo): SignatureHelpItems {
-            const applicableSpan = argumentListInfo.argumentsSpan;
-            const isTypeParameterList = argumentListInfo.kind === ArgumentListKind.TypeArguments;
+        return undefined;
+    }
 
-            const invocation = argumentListInfo.invocation;
-            const callTarget = getInvokedExpression(invocation);
-            const callTargetSymbol = typeChecker.getSymbolAtLocation(callTarget);
-            const callTargetDisplayParts = callTargetSymbol && symbolToDisplayParts(typeChecker, callTargetSymbol, /*enclosingDeclaration*/ undefined, /*meaning*/ undefined);
-            const items: SignatureHelpItem[] = map(candidates, candidateSignature => {
-                let signatureHelpParameters: SignatureHelpParameter[];
-                const prefixDisplayParts: SymbolDisplayPart[] = [];
-                const suffixDisplayParts: SymbolDisplayPart[] = [];
+    function getArgumentIndex(argumentsList: Node, node: Node) {
+        // The list we got back can include commas.  In the presence of errors it may 
+        // also just have nodes without commas.  For example "Foo(a b c)" will have 3 
+        // args without commas.   We want to find what index we're at.  So we count
+        // forward until we hit ourselves, only incrementing the index if it isn't a
+        // comma.
+        //
+        // Note: the subtlety around trailing commas (in getArgumentCount) does not apply
+        // here.  That's because we're only walking forward until we hit the node we're
+        // on.  In that case, even if we're after the trailing comma, we'll still see
+        // that trailing comma in the list, and we'll have generated the appropriate
+        // arg index.
+        let argumentIndex = 0;
+        const listChildren = argumentsList.getChildren();
+        for (const child of listChildren) {
+            if (child === node) {
+                break;
+            }
+            if (child.kind !== SyntaxKind.CommaToken) {
+                argumentIndex++;
+            }
+        }
 
-                if (callTargetDisplayParts) {
-                    addRange(prefixDisplayParts, callTargetDisplayParts);
-                }
+        return argumentIndex;
+    }
 
-                if (isTypeParameterList) {
-                    prefixDisplayParts.push(punctuationPart(SyntaxKind.LessThanToken));
-                    const typeParameters = candidateSignature.typeParameters;
-                    signatureHelpParameters = typeParameters && typeParameters.length > 0 ? map(typeParameters, createSignatureHelpParameterForTypeParameter) : emptyArray;
-                    suffixDisplayParts.push(punctuationPart(SyntaxKind.GreaterThanToken));
-                    const parameterParts = mapToDisplayParts(writer =>
-                        typeChecker.getSymbolDisplayBuilder().buildDisplayForParametersAndDelimiters(candidateSignature.thisType, candidateSignature.parameters, writer, invocation));
-                    addRange(suffixDisplayParts, parameterParts);
-                }
-                else {
-                    const typeParameterParts = mapToDisplayParts(writer =>
-                        typeChecker.getSymbolDisplayBuilder().buildDisplayForTypeParametersAndDelimiters(candidateSignature.typeParameters, writer, invocation));
-                    addRange(prefixDisplayParts, typeParameterParts);
-                    prefixDisplayParts.push(punctuationPart(SyntaxKind.OpenParenToken));
+    function getArgumentCount(argumentsList: Node) {
+        // The argument count for a list is normally the number of non-comma children it has.
+        // For example, if you have "Foo(a,b)" then there will be three children of the arg
+        // list 'a' '<comma>' 'b'.  So, in this case the arg count will be 2.  However, there
+        // is a small subtlety.  If you have  "Foo(a,)", then the child list will just have
+        // 'a' '<comma>'.  So, in the case where the last child is a comma, we increase the
+        // arg count by one to compensate.
+        //
+        // Note: this subtlety only applies to the last comma.  If you had "Foo(a,,"  then 
+        // we'll have:  'a' '<comma>' '<missing>' 
+        // That will give us 2 non-commas.  We then add one for the last comma, givin us an
+        // arg count of 3.
+        const listChildren = argumentsList.getChildren();
 
-                    const parameters = candidateSignature.parameters;
-                    signatureHelpParameters = parameters.length > 0 ? map(parameters, createSignatureHelpParameterForParameter) : emptyArray;
-                    suffixDisplayParts.push(punctuationPart(SyntaxKind.CloseParenToken));
-                }
+        let argumentCount = countWhere(listChildren, arg => arg.kind !== SyntaxKind.CommaToken);
+        if (listChildren.length > 0 && lastOrUndefined(listChildren).kind === SyntaxKind.CommaToken) {
+            argumentCount++;
+        }
 
-                const returnTypeParts = mapToDisplayParts(writer =>
-                    typeChecker.getSymbolDisplayBuilder().buildReturnTypeDisplay(candidateSignature, writer, invocation));
-                addRange(suffixDisplayParts, returnTypeParts);
+        return argumentCount;
+    }
 
-                return {
-                    isVariadic: candidateSignature.hasRestParameter,
-                    prefixDisplayParts,
-                    suffixDisplayParts,
-                    separatorDisplayParts: [punctuationPart(SyntaxKind.CommaToken), spacePart()],
-                    parameters: signatureHelpParameters,
-                    documentation: candidateSignature.getDocumentationComment()
-                };
-            });
+    // spanIndex is either the index for a given template span.
+    // This does not give appropriate results for a NoSubstitutionTemplateLiteral
+    function getArgumentIndexForTemplatePiece(spanIndex: number, node: Node, position: number): number {
+        // Because the TemplateStringsArray is the first argument, we have to offset each substitution expression by 1.
+        // There are three cases we can encounter:
+        //      1. We are precisely in the template literal (argIndex = 0).
+        //      2. We are in or to the right of the substitution expression (argIndex = spanIndex + 1).
+        //      3. We are directly to the right of the template literal, but because we look for the token on the left,
+        //          not enough to put us in the substitution expression; we should consider ourselves part of
+        //          the *next* span's expression by offsetting the index (argIndex = (spanIndex + 1) + 1).
+        //
+        // Example: f  `# abcd $#{#  1 + 1#  }# efghi ${ #"#hello"#  }  #  `
+        //              ^       ^ ^       ^   ^          ^ ^      ^     ^
+        // Case:        1       1 3       2   1          3 2      2     1
+        Debug.assert(position >= node.getStart(), "Assumed 'position' could not occur before node.");
+        if (isTemplateLiteralKind(node.kind)) {
+            if (isInsideTemplateLiteral(<LiteralExpression>node, position)) {
+                return 0;
+            }
+            return spanIndex + 2;
+        }
+        return spanIndex + 1;
+    }
 
-            const argumentIndex = argumentListInfo.argumentIndex;
+    function getArgumentListInfoForTemplate(tagExpression: TaggedTemplateExpression, argumentIndex: number, sourceFile: SourceFile): ArgumentListInfo {
+        // argumentCount is either 1 or (numSpans + 1) to account for the template strings array argument.
+        const argumentCount = tagExpression.template.kind === SyntaxKind.NoSubstitutionTemplateLiteral
+            ? 1
+            : (<TemplateExpression>tagExpression.template).templateSpans.length + 1;
 
-            // argumentCount is the *apparent* number of arguments.
-            const argumentCount = argumentListInfo.argumentCount;
+        Debug.assert(argumentIndex === 0 || argumentIndex < argumentCount, `argumentCount < argumentIndex, ${argumentCount} < ${argumentIndex}`);
 
-            let selectedItemIndex = candidates.indexOf(bestSignature);
-            if (selectedItemIndex < 0) {
-                selectedItemIndex = selectBestInvalidOverloadIndex(candidates, argumentCount);
+        return {
+            kind: ArgumentListKind.TaggedTemplateArguments,
+            invocation: tagExpression,
+            argumentsSpan: getApplicableSpanForTaggedTemplate(tagExpression, sourceFile),
+            argumentIndex: argumentIndex,
+            argumentCount: argumentCount
+        };
+    }
+
+    function getApplicableSpanForArguments(argumentsList: Node, sourceFile: SourceFile): TextSpan {
+        // We use full start and skip trivia on the end because we want to include trivia on
+        // both sides. For example,
+        //
+        //    foo(   /*comment */     a, b, c      /*comment*/     )
+        //        |                                               |
+        //
+        // The applicable span is from the first bar to the second bar (inclusive,
+        // but not including parentheses)
+        const applicableSpanStart = argumentsList.getFullStart();
+        const applicableSpanEnd = skipTrivia(sourceFile.text, argumentsList.getEnd(), /*stopAfterLineBreak*/ false);
+        return createTextSpan(applicableSpanStart, applicableSpanEnd - applicableSpanStart);
+    }
+
+    function getApplicableSpanForTaggedTemplate(taggedTemplate: TaggedTemplateExpression, sourceFile: SourceFile): TextSpan {
+        const template = taggedTemplate.template;
+        const applicableSpanStart = template.getStart();
+        let applicableSpanEnd = template.getEnd();
+
+        // We need to adjust the end position for the case where the template does not have a tail.
+        // Otherwise, we will not show signature help past the expression.
+        // For example,
+        //
+        //      `  ${ 1 + 1        foo(10)
+        //       |        |
+        //
+        // This is because a Missing node has no width. However, what we actually want is to include trivia
+        // leading up to the next token in case the user is about to type in a TemplateMiddle or TemplateTail.
+        if (template.kind === SyntaxKind.TemplateExpression) {
+            const lastSpan = lastOrUndefined((<TemplateExpression>template).templateSpans);
+            if (lastSpan.literal.getFullWidth() === 0) {
+                applicableSpanEnd = skipTrivia(sourceFile.text, applicableSpanEnd, /*stopAfterLineBreak*/ false);
+            }
+        }
+
+        return createTextSpan(applicableSpanStart, applicableSpanEnd - applicableSpanStart);
+    }
+
+    export function getContainingArgumentInfo(node: Node, position: number, sourceFile: SourceFile): ArgumentListInfo {
+        for (let n = node; n.kind !== SyntaxKind.SourceFile; n = n.parent) {
+            if (isFunctionBlock(n)) {
+                return undefined;
             }
 
-            Debug.assert(argumentIndex === 0 || argumentIndex < argumentCount, `argumentCount < argumentIndex, ${argumentCount} < ${argumentIndex}`);
+            // If the node is not a subspan of its parent, this is a big problem.
+            // There have been crashes that might be caused by this violation.
+            if (n.pos < n.parent.pos || n.end > n.parent.end) {
+                Debug.fail("Node of kind " + n.kind + " is not a subspan of its parent of kind " + n.parent.kind);
+            }
+
+            const argumentInfo = getImmediatelyContainingArgumentInfo(n, position, sourceFile);
+            if (argumentInfo) {
+                return argumentInfo;
+            }
+
+
+            // TODO: Handle generic call with incomplete syntax
+        }
+        return undefined;
+    }
+
+    function getChildListThatStartsWithOpenerToken(parent: Node, openerToken: Node, sourceFile: SourceFile): Node {
+        const children = parent.getChildren(sourceFile);
+        const indexOfOpenerToken = children.indexOf(openerToken);
+        Debug.assert(indexOfOpenerToken >= 0 && children.length > indexOfOpenerToken + 1);
+        return children[indexOfOpenerToken + 1];
+    }
+
+    /**
+     * The selectedItemIndex could be negative for several reasons.
+     *     1. There are too many arguments for all of the overloads
+     *     2. None of the overloads were type compatible
+     * The solution here is to try to pick the best overload by picking
+     * either the first one that has an appropriate number of parameters,
+     * or the one with the most parameters.
+     */
+    function selectBestInvalidOverloadIndex(candidates: Signature[], argumentCount: number): number {
+        let maxParamsSignatureIndex = -1;
+        let maxParams = -1;
+        for (let i = 0; i < candidates.length; i++) {
+            const candidate = candidates[i];
+
+            if (candidate.hasRestParameter || candidate.parameters.length >= argumentCount) {
+                return i;
+            }
+
+            if (candidate.parameters.length > maxParams) {
+                maxParams = candidate.parameters.length;
+                maxParamsSignatureIndex = i;
+            }
+        }
+
+        return maxParamsSignatureIndex;
+    }
+
+    function createSignatureHelpItems(candidates: Signature[], bestSignature: Signature, argumentListInfo: ArgumentListInfo, typeChecker: TypeChecker): SignatureHelpItems {
+        const applicableSpan = argumentListInfo.argumentsSpan;
+        const isTypeParameterList = argumentListInfo.kind === ArgumentListKind.TypeArguments;
+
+        const invocation = argumentListInfo.invocation;
+        const callTarget = getInvokedExpression(invocation);
+        const callTargetSymbol = typeChecker.getSymbolAtLocation(callTarget);
+        const callTargetDisplayParts = callTargetSymbol && symbolToDisplayParts(typeChecker, callTargetSymbol, /*enclosingDeclaration*/ undefined, /*meaning*/ undefined);
+        const items: SignatureHelpItem[] = map(candidates, candidateSignature => {
+            let signatureHelpParameters: SignatureHelpParameter[];
+            const prefixDisplayParts: SymbolDisplayPart[] = [];
+            const suffixDisplayParts: SymbolDisplayPart[] = [];
+
+            if (callTargetDisplayParts) {
+                addRange(prefixDisplayParts, callTargetDisplayParts);
+            }
+
+            if (isTypeParameterList) {
+                prefixDisplayParts.push(punctuationPart(SyntaxKind.LessThanToken));
+                const typeParameters = candidateSignature.typeParameters;
+                signatureHelpParameters = typeParameters && typeParameters.length > 0 ? map(typeParameters, createSignatureHelpParameterForTypeParameter) : emptyArray;
+                suffixDisplayParts.push(punctuationPart(SyntaxKind.GreaterThanToken));
+                const parameterParts = mapToDisplayParts(writer =>
+                    typeChecker.getSymbolDisplayBuilder().buildDisplayForParametersAndDelimiters(candidateSignature.thisType, candidateSignature.parameters, writer, invocation));
+                addRange(suffixDisplayParts, parameterParts);
+            }
+            else {
+                const typeParameterParts = mapToDisplayParts(writer =>
+                    typeChecker.getSymbolDisplayBuilder().buildDisplayForTypeParametersAndDelimiters(candidateSignature.typeParameters, writer, invocation));
+                addRange(prefixDisplayParts, typeParameterParts);
+                prefixDisplayParts.push(punctuationPart(SyntaxKind.OpenParenToken));
+
+                const parameters = candidateSignature.parameters;
+                signatureHelpParameters = parameters.length > 0 ? map(parameters, createSignatureHelpParameterForParameter) : emptyArray;
+                suffixDisplayParts.push(punctuationPart(SyntaxKind.CloseParenToken));
+            }
+
+            const returnTypeParts = mapToDisplayParts(writer =>
+                typeChecker.getSymbolDisplayBuilder().buildReturnTypeDisplay(candidateSignature, writer, invocation));
+            addRange(suffixDisplayParts, returnTypeParts);
 
             return {
-                items,
-                applicableSpan,
-                selectedItemIndex,
-                argumentIndex,
-                argumentCount
+                isVariadic: candidateSignature.hasRestParameter,
+                prefixDisplayParts,
+                suffixDisplayParts,
+                separatorDisplayParts: [punctuationPart(SyntaxKind.CommaToken), spacePart()],
+                parameters: signatureHelpParameters,
+                documentation: candidateSignature.getDocumentationComment()
             };
+        });
 
-            function createSignatureHelpParameterForParameter(parameter: Symbol): SignatureHelpParameter {
-                const displayParts = mapToDisplayParts(writer =>
-                    typeChecker.getSymbolDisplayBuilder().buildParameterDisplay(parameter, writer, invocation));
+        const argumentIndex = argumentListInfo.argumentIndex;
 
-                return {
-                    name: parameter.name,
-                    documentation: parameter.getDocumentationComment(),
-                    displayParts,
-                    isOptional: typeChecker.isOptionalParameter(<ParameterDeclaration>parameter.valueDeclaration)
-                };
-            }
+        // argumentCount is the *apparent* number of arguments.
+        const argumentCount = argumentListInfo.argumentCount;
 
-            function createSignatureHelpParameterForTypeParameter(typeParameter: TypeParameter): SignatureHelpParameter {
-                const displayParts = mapToDisplayParts(writer =>
-                    typeChecker.getSymbolDisplayBuilder().buildTypeParameterDisplay(typeParameter, writer, invocation));
+        let selectedItemIndex = candidates.indexOf(bestSignature);
+        if (selectedItemIndex < 0) {
+            selectedItemIndex = selectBestInvalidOverloadIndex(candidates, argumentCount);
+        }
 
-                return {
-                    name: typeParameter.symbol.name,
-                    documentation: emptyArray,
-                    displayParts,
-                    isOptional: false
-                };
-            }
+        Debug.assert(argumentIndex === 0 || argumentIndex < argumentCount, `argumentCount < argumentIndex, ${argumentCount} < ${argumentIndex}`);
+
+        return {
+            items,
+            applicableSpan,
+            selectedItemIndex,
+            argumentIndex,
+            argumentCount
+        };
+
+        function createSignatureHelpParameterForParameter(parameter: Symbol): SignatureHelpParameter {
+            const displayParts = mapToDisplayParts(writer =>
+                typeChecker.getSymbolDisplayBuilder().buildParameterDisplay(parameter, writer, invocation));
+
+            return {
+                name: parameter.name,
+                documentation: parameter.getDocumentationComment(),
+                displayParts,
+                isOptional: typeChecker.isOptionalParameter(<ParameterDeclaration>parameter.valueDeclaration)
+            };
+        }
+
+        function createSignatureHelpParameterForTypeParameter(typeParameter: TypeParameter): SignatureHelpParameter {
+            const displayParts = mapToDisplayParts(writer =>
+                typeChecker.getSymbolDisplayBuilder().buildTypeParameterDisplay(typeParameter, writer, invocation));
+
+            return {
+                name: typeParameter.symbol.name,
+                documentation: emptyArray,
+                displayParts,
+                isOptional: false
+            };
         }
     }
 }

src/services/utilities.ts

@@ -426,9 +426,27 @@ namespace ts {
         }
     }
 
-    export function isInString(sourceFile: SourceFile, position: number) {
-        const token = getTokenAtPosition(sourceFile, position);
-        return token && (token.kind === SyntaxKind.StringLiteral || token.kind === SyntaxKind.StringLiteralType) && position > token.getStart(sourceFile);
+    export function isInString(sourceFile: SourceFile, position: number): boolean {
+        const previousToken = findPrecedingToken(position, sourceFile);
+        if (previousToken &&
+            (previousToken.kind === SyntaxKind.StringLiteral || previousToken.kind === SyntaxKind.StringLiteralType)) {
+            const start = previousToken.getStart();
+            const end = previousToken.getEnd();
+
+            // To be "in" one of these literals, the position has to be:
+            //   1. entirely within the token text.
+            //   2. at the end position of an unterminated token.
+            //   3. at the end of a regular expression (due to trailing flags like '/foo/g').
+            if (start < position && position < end) {
+                return true;
+            }
+
+            if (position === end) {
+                return !!(<LiteralExpression>previousToken).isUnterminated;
+            }
+        }
+
+        return false;
     }
 
     export function isInComment(sourceFile: SourceFile, position: number) {