Cherry-pick PR #35335 into release-3.7

Component commits:
c44de23 Fix compileOnSaveEmit when using source of project reference redirect with --out Fixes #35226

src/compiler/emitter.ts

@@ -23,7 +23,7 @@ namespace ts {
         forceDtsEmit = false,
         onlyBuildInfo?: boolean,
         includeBuildInfo?: boolean) {
-        const sourceFiles = isArray(sourceFilesOrTargetSourceFile) ? sourceFilesOrTargetSourceFile : getSourceFilesToEmit(host, sourceFilesOrTargetSourceFile);
+        const sourceFiles = isArray(sourceFilesOrTargetSourceFile) ? sourceFilesOrTargetSourceFile : getSourceFilesToEmit(host, sourceFilesOrTargetSourceFile, forceDtsEmit);
         const options = host.getCompilerOptions();
         if (options.outFile || options.out) {
             const prepends = host.getPrependNodes();
@@ -274,7 +274,7 @@ namespace ts {
         forEachEmittedFile(
             host,
             emitSourceFileOrBundle,
-            getSourceFilesToEmit(host, targetSourceFile),
+            getSourceFilesToEmit(host, targetSourceFile, forceDtsEmit),
             forceDtsEmit,
             onlyBuildInfo,
             !targetSourceFile
@@ -754,6 +754,7 @@ namespace ts {
             getLibFileFromReference: notImplemented,
             isSourceFileFromExternalLibrary: returnFalse,
             getResolvedProjectReferenceToRedirect: returnUndefined,
+            isSourceOfProjectReferenceRedirect: returnFalse,
             writeFile: (name, text, writeByteOrderMark) => {
                 switch (name) {
                     case jsFilePath:

src/compiler/program.ts

@@ -1010,15 +1010,9 @@ namespace ts {
             return ts.toPath(fileName, currentDirectory, getCanonicalFileName);
         }
 
-        function isValidSourceFileForEmit(file: SourceFile) {
-            // source file is allowed to be emitted and its not source of project reference redirect
-            return sourceFileMayBeEmitted(file, options, isSourceFileFromExternalLibrary, getResolvedProjectReferenceToRedirect) &&
-                !isSourceOfProjectReferenceRedirect(file.fileName);
-        }
-
         function getCommonSourceDirectory() {
             if (commonSourceDirectory === undefined) {
-                const emittedFiles = filter(files, file => isValidSourceFileForEmit(file));
+                const emittedFiles = filter(files, file => sourceFileMayBeEmitted(file, program));
                 if (options.rootDir && checkSourceFilesBelongToPath(emittedFiles, options.rootDir)) {
                     // If a rootDir is specified use it as the commonSourceDirectory
                     commonSourceDirectory = getNormalizedAbsolutePath(options.rootDir, currentDirectory);
@@ -1477,6 +1471,7 @@ namespace ts {
                 getLibFileFromReference: program.getLibFileFromReference,
                 isSourceFileFromExternalLibrary,
                 getResolvedProjectReferenceToRedirect,
+                isSourceOfProjectReferenceRedirect,
                 getProbableSymlinks,
                 writeFile: writeFileCallback || (
                     (fileName, data, writeByteOrderMark, onError, sourceFiles) => host.writeFile(fileName, data, writeByteOrderMark, onError, sourceFiles)),
@@ -2945,7 +2940,7 @@ namespace ts {
                 const rootPaths = arrayToSet(rootNames, toPath);
                 for (const file of files) {
                     // Ignore file that is not emitted
-                    if (isValidSourceFileForEmit(file) && !rootPaths.has(file.path)) {
+                    if (sourceFileMayBeEmitted(file, program) && !rootPaths.has(file.path)) {
                         addProgramDiagnosticAtRefPath(
                             file,
                             rootPaths,

src/compiler/types.ts

@@ -5714,13 +5714,19 @@ namespace ts {
     }
 
     /* @internal */
-    export interface EmitHost extends ScriptReferenceHost, ModuleSpecifierResolutionHost {
+    export interface SourceFileMapBeEmittedHost {
+        getCompilerOptions(): CompilerOptions;
+        isSourceFileFromExternalLibrary(file: SourceFile): boolean;
+        getResolvedProjectReferenceToRedirect(fileName: string): ResolvedProjectReference | undefined;
+        isSourceOfProjectReferenceRedirect(fileName: string): boolean;
+    }
+
+    /* @internal */
+    export interface EmitHost extends ScriptReferenceHost, ModuleSpecifierResolutionHost, SourceFileMapBeEmittedHost {
         getSourceFiles(): readonly SourceFile[];
         useCaseSensitiveFileNames(): boolean;
         getCurrentDirectory(): string;
 
-        isSourceFileFromExternalLibrary(file: SourceFile): boolean;
-        getResolvedProjectReferenceToRedirect(fileName: string): ResolvedProjectReference | undefined;
         getLibFileFromReference(ref: FileReference): SourceFile | undefined;
 
         getCommonSourceDirectory(): string;

src/compiler/utilities.ts

@@ -3659,34 +3659,36 @@ namespace ts {
      * @param host An EmitHost.
      * @param targetSourceFile An optional target source file to emit.
      */
-    export function getSourceFilesToEmit(host: EmitHost, targetSourceFile?: SourceFile): readonly SourceFile[] {
+    export function getSourceFilesToEmit(host: EmitHost, targetSourceFile?: SourceFile, forceDtsEmit?: boolean): readonly SourceFile[] {
         const options = host.getCompilerOptions();
-        const isSourceFileFromExternalLibrary = (file: SourceFile) => host.isSourceFileFromExternalLibrary(file);
-        const getResolvedProjectReferenceToRedirect = (fileName: string) => host.getResolvedProjectReferenceToRedirect(fileName);
         if (options.outFile || options.out) {
             const moduleKind = getEmitModuleKind(options);
             const moduleEmitEnabled = options.emitDeclarationOnly || moduleKind === ModuleKind.AMD || moduleKind === ModuleKind.System;
             // Can emit only sources that are not declaration file and are either non module code or module with --module or --target es6 specified
-            return filter(host.getSourceFiles(), sourceFile =>
-                (moduleEmitEnabled || !isExternalModule(sourceFile)) && sourceFileMayBeEmitted(sourceFile, options, isSourceFileFromExternalLibrary, getResolvedProjectReferenceToRedirect));
+            return filter(
+                host.getSourceFiles(),
+                sourceFile =>
+                    (moduleEmitEnabled || !isExternalModule(sourceFile)) &&
+                    sourceFileMayBeEmitted(sourceFile, host, forceDtsEmit)
+            );
         }
         else {
             const sourceFiles = targetSourceFile === undefined ? host.getSourceFiles() : [targetSourceFile];
-            return filter(sourceFiles, sourceFile => sourceFileMayBeEmitted(sourceFile, options, isSourceFileFromExternalLibrary, getResolvedProjectReferenceToRedirect));
+            return filter(
+                sourceFiles,
+                sourceFile => sourceFileMayBeEmitted(sourceFile, host, forceDtsEmit)
+            );
         }
     }
 
     /** Don't call this for `--outFile`, just for `--outDir` or plain emit. `--outFile` needs additional checks. */
-    export function sourceFileMayBeEmitted(
-        sourceFile: SourceFile,
-        options: CompilerOptions,
-        isSourceFileFromExternalLibrary: (file: SourceFile) => boolean,
-        getResolvedProjectReferenceToRedirect: (fileName: string) => ResolvedProjectReference | undefined
-    ) {
+    export function sourceFileMayBeEmitted(sourceFile: SourceFile, host: SourceFileMapBeEmittedHost, forceDtsEmit?: boolean) {
+        const options = host.getCompilerOptions();
         return !(options.noEmitForJsFiles && isSourceFileJS(sourceFile)) &&
             !sourceFile.isDeclarationFile &&
-            !isSourceFileFromExternalLibrary(sourceFile) &&
-            !(isJsonSourceFile(sourceFile) && getResolvedProjectReferenceToRedirect(sourceFile.fileName));
+            !host.isSourceFileFromExternalLibrary(sourceFile) &&
+            !(isJsonSourceFile(sourceFile) && host.getResolvedProjectReferenceToRedirect(sourceFile.fileName)) &&
+            (forceDtsEmit || !host.isSourceOfProjectReferenceRedirect(sourceFile.fileName));
     }
 
     export function getSourceFilePathInNewDir(fileName: string, host: EmitHost, newDirPath: string): string {

src/testRunner/unittests/tsserver/projectReferenceCompileOnSave.ts

@@ -406,4 +406,83 @@ ${appendDts}`
             });
         });
     });
+
+    describe("unittests:: tsserver:: with project references and compile on save with external projects", () => {
+        it("compile on save emits same output as project build", () => {
+            const tsbaseJson: File = {
+                path: `${projectRoot}/tsbase.json`,
+                content: JSON.stringify({
+                    compileOnSave: true,
+                    compilerOptions: {
+                        module: "none",
+                        composite: true
+                    }
+                })
+            };
+            const buttonClass = `${projectRoot}/buttonClass`;
+            const buttonConfig: File = {
+                path: `${buttonClass}/tsconfig.json`,
+                content: JSON.stringify({
+                    extends: "../tsbase.json",
+                    compilerOptions: {
+                        outFile: "Source.js"
+                    },
+                    files: ["Source.ts"]
+                })
+            };
+            const buttonSource: File = {
+                path: `${buttonClass}/Source.ts`,
+                content: `module Hmi {
+    export class Button {
+        public static myStaticFunction() {
+        }
+    }
+}`
+            };
+
+            const siblingClass = `${projectRoot}/SiblingClass`;
+            const siblingConfig: File = {
+                path: `${siblingClass}/tsconfig.json`,
+                content: JSON.stringify({
+                    extends: "../tsbase.json",
+                    references: [{
+                        path: "../buttonClass/"
+                    }],
+                    compilerOptions: {
+                        outFile: "Source.js"
+                    },
+                    files: ["Source.ts"]
+                })
+            };
+            const siblingSource: File = {
+                path: `${siblingClass}/Source.ts`,
+                content: `module Hmi {
+    export class Sibling {
+        public mySiblingFunction() {
+        }
+    }
+}`
+            };
+            const host = createServerHost([libFile, tsbaseJson, buttonConfig, buttonSource, siblingConfig, siblingSource], { useCaseSensitiveFileNames: true });
+
+            // ts build should succeed
+            const solutionBuilder = tscWatch.createSolutionBuilder(host, [siblingConfig.path], {});
+            solutionBuilder.build();
+            assert.equal(host.getOutput().length, 0, JSON.stringify(host.getOutput(), /*replacer*/ undefined, " "));
+            const sourceJs = changeExtension(siblingSource.path, ".js");
+            const expectedSiblingJs = host.readFile(sourceJs);
+
+            const session = createSession(host);
+            openFilesForSession([siblingSource], session);
+
+            session.executeCommandSeq<protocol.CompileOnSaveEmitFileRequest>({
+                command: protocol.CommandTypes.CompileOnSaveEmitFile,
+                arguments: {
+                    file: siblingSource.path,
+                    projectFileName: siblingConfig.path
+                }
+            });
+            assert.equal(host.readFile(sourceJs), expectedSiblingJs);
+        });
+    });
 }