Merge branch 'master' into createTypeNode

src/compiler/parser.ts

@@ -3863,6 +3863,9 @@ namespace ts {
                     parseErrorAtPosition(openingTagName.pos, openingTagName.end - openingTagName.pos, Diagnostics.JSX_element_0_has_no_corresponding_closing_tag, getTextOfNodeFromSourceText(sourceText, openingTagName));
                     break;
                 }
+                else if (token() === SyntaxKind.ConflictMarkerTrivia) {
+                    break;
+                }
                 result.push(parseJsxChild());
             }
 

src/compiler/scanner.ts

@@ -1716,7 +1716,14 @@ namespace ts {
             while (pos < end) {
                 pos++;
                 char = text.charCodeAt(pos);
-                if ((char === CharacterCodes.openBrace) || (char === CharacterCodes.lessThan)) {
+                if (char === CharacterCodes.openBrace) {
+                    break;
+                }
+                if (char === CharacterCodes.lessThan) {
+                    if (isConflictMarkerTrivia(text, pos)) {
+                        pos = scanConflictMarkerTrivia(text, pos, error);
+                        return token = SyntaxKind.ConflictMarkerTrivia;
+                    }
                     break;
                 }
             }

src/compiler/sys.ts

@@ -202,7 +202,7 @@ namespace ts {
                 if (len >= 2 && buffer[0] === 0xFE && buffer[1] === 0xFF) {
                     // Big endian UTF-16 byte order mark detected. Since big endian is not supported by node.js,
                     // flip all byte pairs and treat as little endian.
-                    len &= ~1;
+                    len &= ~1; // Round down to a multiple of 2
                     for (let i = 0; i < len; i += 2) {
                         const temp = buffer[i];
                         buffer[i] = buffer[i + 1];

src/compiler/transformers/module/module.ts

@@ -89,7 +89,8 @@ namespace ts {
             startLexicalEnvironment();
 
             const statements: Statement[] = [];
-            const statementOffset = addPrologueDirectives(statements, node.statements, /*ensureUseStrict*/ !compilerOptions.noImplicitUseStrict, sourceElementVisitor);
+            const ensureUseStrict = compilerOptions.alwaysStrict || (!compilerOptions.noImplicitUseStrict && isExternalModule(currentSourceFile));
+            const statementOffset = addPrologueDirectives(statements, node.statements, ensureUseStrict, sourceElementVisitor);
 
             if (shouldEmitUnderscoreUnderscoreESModule()) {
                 append(statements, createUnderscoreUnderscoreESModule());

src/compiler/transformers/module/system.ts

@@ -225,7 +225,8 @@ namespace ts {
             startLexicalEnvironment();
 
             // Add any prologue directives.
-            const statementOffset = addPrologueDirectives(statements, node.statements, /*ensureUseStrict*/ !compilerOptions.noImplicitUseStrict, sourceElementVisitor);
+            const ensureUseStrict = compilerOptions.alwaysStrict || (!compilerOptions.noImplicitUseStrict && isExternalModule(currentSourceFile));
+            const statementOffset = addPrologueDirectives(statements, node.statements, ensureUseStrict, sourceElementVisitor);
 
             // var __moduleName = context_1 && context_1.id;
             statements.push(

src/harness/unittests/tsserverProjectSystem.ts

@@ -3006,6 +3006,42 @@ namespace ts.projectSystem {
             const errorResult = <protocol.Diagnostic[]>session.executeCommand(dTsFileGetErrRequest).response;
             assert.isTrue(errorResult.length === 0);
         });
+
+        it("should be turned on for js-only external projects with skipLibCheck=false", () => {
+            const jsFile = {
+                path: "/a/b/file1.js",
+                content: "let x =1;"
+            };
+            const dTsFile = {
+                path: "/a/b/file2.d.ts",
+                content: `
+                interface T {
+                    name: string;
+                };
+                interface T {
+                    name: number;
+                };`
+            };
+            const host = createServerHost([jsFile, dTsFile]);
+            const session = createSession(host);
+
+            const openExternalProjectRequest = makeSessionRequest<protocol.OpenExternalProjectArgs>(
+                CommandNames.OpenExternalProject,
+                {
+                    projectFileName: "project1",
+                    rootFiles: toExternalFiles([jsFile.path, dTsFile.path]),
+                    options: { skipLibCheck: false }
+                }
+            );
+            session.executeCommand(openExternalProjectRequest);
+
+            const dTsFileGetErrRequest = makeSessionRequest<protocol.SemanticDiagnosticsSyncRequestArgs>(
+                CommandNames.SemanticDiagnosticsSync,
+                { file: dTsFile.path }
+            );
+            const errorResult = <protocol.Diagnostic[]>session.executeCommand(dTsFileGetErrRequest).response;
+            assert.isTrue(errorResult.length === 0);
+        });
     });
 
     describe("non-existing directories listed in config file input array", () => {

src/server/session.ts

@@ -26,14 +26,7 @@ namespace ts.server {
     }
 
     function shouldSkipSematicCheck(project: Project) {
-        if (project.getCompilerOptions().skipLibCheck !== undefined) {
-            return false;
-        }
-
-        if ((project.projectKind === ProjectKind.Inferred || project.projectKind === ProjectKind.External) && project.isJsOnlyProject()) {
-            return true;
-        }
-        return false;
+        return (project.projectKind === ProjectKind.Inferred || project.projectKind === ProjectKind.External) && project.isJsOnlyProject();
     }
 
     interface FileStart {