Correctly set filesByName map when reusing program to ensure it is same as old (#35784)

It was previously not populated correctly if preserveSymlinks with useSourceOfProjectReference was true,
in that case if module was resolved to symlink and we deduced it refers to source of project reference we want to set "resolvedFileName" correctly
otherwise it results in incorrect module not found errors.

src/compiler/program.ts

@@ -933,6 +933,7 @@ namespace ts {
             getSourceFiles: () => files,
             getMissingFilePaths: () => missingFilePaths!, // TODO: GH#18217
             getRefFileMap: () => refFileMap,
+            getFilesByNameMap: () => filesByName,
             getCompilerOptions: () => options,
             getSyntacticDiagnostics,
             getOptionsDiagnostics,
@@ -1422,21 +1423,25 @@ namespace ts {
             refFileMap = oldProgram.getRefFileMap();
 
             // update fileName -> file mapping
+            Debug.assert(newSourceFiles.length === oldProgram.getSourceFiles().length);
             for (const newSourceFile of newSourceFiles) {
-                const filePath = newSourceFile.path;
-                addFileToFilesByName(newSourceFile, filePath, newSourceFile.resolvedPath);
-                if (useSourceOfProjectReferenceRedirect) {
-                    const redirectProject = getProjectReferenceRedirectProject(newSourceFile.fileName);
-                    if (redirectProject && !(redirectProject.commandLine.options.outFile || redirectProject.commandLine.options.out)) {
-                        const redirect = getProjectReferenceOutputName(redirectProject, newSourceFile.fileName);
-                        addFileToFilesByName(newSourceFile, toPath(redirect), /*redirectedPath*/ undefined);
-                    }
-                }
-                // Set the file as found during node modules search if it was found that way in old progra,
-                if (oldProgram.isSourceFileFromExternalLibrary(oldProgram.getSourceFileByPath(newSourceFile.resolvedPath)!)) {
-                    sourceFilesFoundSearchingNodeModules.set(filePath, true);
-                }
+                filesByName.set(newSourceFile.path, newSourceFile);
             }
+            const oldFilesByNameMap = oldProgram.getFilesByNameMap();
+            oldFilesByNameMap.forEach((oldFile, path) => {
+                if (!oldFile) {
+                    filesByName.set(path, oldFile);
+                    return;
+                }
+                if (oldFile.path === path) {
+                    // Set the file as found during node modules search if it was found that way in old progra,
+                    if (oldProgram!.isSourceFileFromExternalLibrary(oldFile)) {
+                        sourceFilesFoundSearchingNodeModules.set(oldFile.path, true);
+                    }
+                    return;
+                }
+                filesByName.set(path, filesByName.get(oldFile.path));
+            });
 
             files = newSourceFiles;
             fileProcessingDiagnostics = oldProgram.getFileProcessingDiagnostics();

src/compiler/types.ts

@@ -3131,6 +3131,8 @@ namespace ts {
         getMissingFilePaths(): readonly Path[];
         /* @internal */
         getRefFileMap(): MultiMap<RefFile> | undefined;
+        /* @internal */
+        getFilesByNameMap(): Map<SourceFile | false | undefined>;
 
         /**
          * Emits the JavaScript and declaration files.  If targetSourceFile is not specified, then

src/testRunner/unittests/tsserver/projectReferences.ts

@@ -1433,6 +1433,7 @@ function foo() {
                 aTest: File;
                 bFoo: File;
                 bBar: File;
+                bSymlink: SymLink;
             }
             function verifySymlinkScenario(packages: () => Packages) {
                 describe("when solution is not built", () => {
@@ -1456,13 +1457,9 @@ function foo() {
                 });
             }
 
-            function verifySession({ bPackageJson, aTest, bFoo, bBar }: Packages, alreadyBuilt: boolean, extraOptions: CompilerOptions) {
+            function verifySession({ bPackageJson, aTest, bFoo, bBar, bSymlink }: Packages, alreadyBuilt: boolean, extraOptions: CompilerOptions) {
                 const aConfig = config("A", extraOptions, ["../B"]);
                 const bConfig = config("B", extraOptions);
-                const bSymlink: SymLink = {
-                    path: `${tscWatch.projectRoot}/node_modules/b`,
-                    symLink: `${tscWatch.projectRoot}/packages/B`
-                };
                 const files = [libFile, bPackageJson, aConfig, bConfig, aTest, bFoo, bBar, bSymlink];
                 const host = alreadyBuilt ?
                     createHost(files, [aConfig.path]) :
@@ -1485,6 +1482,26 @@ function foo() {
                         { file: aTest, syntax: [], semantic: [], suggestion: [] }
                     ]
                 });
+                session.executeCommandSeq<protocol.UpdateOpenRequest>({
+                    command: protocol.CommandTypes.UpdateOpen,
+                    arguments: {
+                        changedFiles: [{
+                            fileName: aTest.path,
+                            textChanges: [{
+                                newText: "\n",
+                                start: { line: 5, offset: 1 },
+                                end: { line: 5, offset: 1 }
+                            }]
+                        }]
+                    }
+                });
+                verifyGetErrRequest({
+                    host,
+                    session,
+                    expected: [
+                        { file: aTest, syntax: [], semantic: [], suggestion: [] }
+                    ]
+                });
             }
 
             function config(packageName: string, extraOptions: CompilerOptions, references?: string[]): File {
@@ -1510,37 +1527,55 @@ function foo() {
                 };
             }
 
-            describe("when packageJson has types field and has index.ts", () => {
-                verifySymlinkScenario(() => ({
-                    bPackageJson: {
-                        path: `${tscWatch.projectRoot}/packages/B/package.json`,
-                        content: JSON.stringify({
-                            main: "lib/index.js",
-                            types: "lib/index.d.ts"
-                        })
-                    },
-                    aTest: file("A", "index.ts", `import { foo } from 'b';
-import { bar } from 'b/lib/bar';
+            function verifyMonoRepoLike(scope = "") {
+                describe("when packageJson has types field and has index.ts", () => {
+                    verifySymlinkScenario(() => ({
+                        bPackageJson: {
+                            path: `${tscWatch.projectRoot}/packages/B/package.json`,
+                            content: JSON.stringify({
+                                main: "lib/index.js",
+                                types: "lib/index.d.ts"
+                            })
+                        },
+                        aTest: file("A", "index.ts", `import { foo } from '${scope}b';
+import { bar } from '${scope}b/lib/bar';
 foo();
-bar();`),
-                    bFoo: file("B", "index.ts", `export function foo() { }`),
-                    bBar: file("B", "bar.ts", `export function bar() { }`)
-                }));
-            });
+bar();
+`),
+                        bFoo: file("B", "index.ts", `export function foo() { }`),
+                        bBar: file("B", "bar.ts", `export function bar() { }`),
+                        bSymlink: {
+                            path: `${tscWatch.projectRoot}/node_modules/${scope}b`,
+                            symLink: `${tscWatch.projectRoot}/packages/B`
+                        }
+                    }));
+                });
 
-            describe("when referencing file from subFolder", () => {
-                verifySymlinkScenario(() => ({
-                    bPackageJson: {
-                        path: `${tscWatch.projectRoot}/packages/B/package.json`,
-                        content: "{}"
-                    },
-                    aTest: file("A", "test.ts", `import { foo } from 'b/lib/foo';
-import { bar } from 'b/lib/bar/foo';
+                describe("when referencing file from subFolder", () => {
+                    verifySymlinkScenario(() => ({
+                        bPackageJson: {
+                            path: `${tscWatch.projectRoot}/packages/B/package.json`,
+                            content: "{}"
+                        },
+                        aTest: file("A", "test.ts", `import { foo } from '${scope}b/lib/foo';
+import { bar } from '${scope}b/lib/bar/foo';
 foo();
-bar();`),
-                    bFoo: file("B", "foo.ts", `export function foo() { }`),
-                    bBar: file("B", "bar/foo.ts", `export function bar() { }`)
-                }));
+bar();
+`),
+                        bFoo: file("B", "foo.ts", `export function foo() { }`),
+                        bBar: file("B", "bar/foo.ts", `export function bar() { }`),
+                        bSymlink: {
+                            path: `${tscWatch.projectRoot}/node_modules/${scope}b`,
+                            symLink: `${tscWatch.projectRoot}/packages/B`
+                        }
+                    }));
+                });
+            }
+            describe("when package is not scoped", () => {
+                verifyMonoRepoLike();
+            });
+            describe("when package is scoped", () => {
+                verifyMonoRepoLike("@issue/");
             });
         });