Use realpathSync.native on case-insensitive file systems

src/compiler/moduleNameResolver.ts

@@ -280,6 +280,11 @@ namespace ts {
     }
     const nodeModulesAtTypes = combinePaths("node_modules", "@types");
 
+    function arePathsEqual(path1: string, path2: string, host: ModuleResolutionHost): boolean {
+        const useCaseSensitiveFileNames = typeof host.useCaseSensitiveFileNames === "function" ? host.useCaseSensitiveFileNames() : host.useCaseSensitiveFileNames;
+        return comparePaths(path1, path2, !useCaseSensitiveFileNames) === Comparison.EqualTo;
+    }
+
     /**
      * @param {string | undefined} containingFile - file that contains type reference directive, can be undefined if containing file is unknown.
      * This is possible in case if resolution is performed for directives specified via 'types' parameter. In this case initial path for secondary lookups
@@ -343,7 +348,7 @@ namespace ts {
             resolvedTypeReferenceDirective = {
                 primary,
                 resolvedFileName,
-                originalPath: fileName === resolvedFileName ? undefined : fileName,
+                originalPath: arePathsEqual(fileName, resolvedFileName, host) ? undefined : fileName,
                 packageId,
                 isExternalLibraryImport: pathContainsNodeModules(fileName),
             };
@@ -1122,7 +1127,7 @@ namespace ts {
                 let resolvedValue = resolved.value;
                 if (!compilerOptions.preserveSymlinks && resolvedValue && !resolvedValue.originalPath) {
                     const path = realPath(resolvedValue.path, host, traceEnabled);
-                    const originalPath = path === resolvedValue.path ? undefined : resolvedValue.path;
+                    const originalPath = arePathsEqual(path, resolvedValue.path, host) ? undefined : resolvedValue.path;
                     resolvedValue = { ...resolvedValue, path, originalPath };
                 }
                 // For node_modules lookups, get the real path so that multiple accesses to an `npm link`-ed module do not create duplicate files.

src/compiler/program.ts

@@ -1163,21 +1163,20 @@ namespace ts {
 
             // The originalFileName could not be actual source file name if file found was d.ts from referecned project
             // So in this case try to look up if this is output from referenced project, if it is use the redirected project in that case
-            const resultFromDts = getRedirectReferenceForResolutionFromSourceOfProject(file.originalFileName, file.path);
+            const resultFromDts = getRedirectReferenceForResolutionFromSourceOfProject(file.path);
             if (resultFromDts) return resultFromDts;
 
             // If preserveSymlinks is true, module resolution wont jump the symlink
             // but the resolved real path may be the .d.ts from project reference
             // Note:: Currently we try the real path only if the
             // file is from node_modules to avoid having to run real path on all file paths
             if (!host.realpath || !options.preserveSymlinks || !stringContains(file.originalFileName, nodeModulesPathPart)) return undefined;
-            const realDeclarationFileName = host.realpath(file.originalFileName);
-            const realDeclarationPath = toPath(realDeclarationFileName);
-            return realDeclarationPath === file.path ? undefined : getRedirectReferenceForResolutionFromSourceOfProject(realDeclarationFileName, realDeclarationPath);
+            const realDeclarationPath = toPath(host.realpath(file.originalFileName));
+            return realDeclarationPath === file.path ? undefined : getRedirectReferenceForResolutionFromSourceOfProject(realDeclarationPath);
         }
 
-        function getRedirectReferenceForResolutionFromSourceOfProject(fileName: string, filePath: Path) {
-            const source = getSourceOfProjectReferenceRedirect(fileName);
+        function getRedirectReferenceForResolutionFromSourceOfProject(filePath: Path) {
+            const source = getSourceOfProjectReferenceRedirect(filePath);
             if (isString(source)) return getResolvedProjectReferenceToRedirect(source);
             if (!source) return undefined;
             // Output of .d.ts file so return resolved ref that matches the out file name
@@ -2472,7 +2471,7 @@ namespace ts {
         function processSourceFile(fileName: string, isDefaultLib: boolean, ignoreNoDefaultLib: boolean, packageId: PackageId | undefined, reason: FileIncludeReason): void {
             getSourceFileFromReferenceWorker(
                 fileName,
-                fileName => findSourceFile(fileName, toPath(fileName), isDefaultLib, ignoreNoDefaultLib, reason, packageId), // TODO: GH#18217
+                fileName => findSourceFile(fileName, isDefaultLib, ignoreNoDefaultLib, reason, packageId), // TODO: GH#18217
                 (diagnostic, ...args) => addFilePreprocessingFileExplainingDiagnostic(/*file*/ undefined, reason, diagnostic, args),
                 reason
             );
@@ -2514,20 +2513,21 @@ namespace ts {
         }
 
         // Get source file from normalized fileName
-        function findSourceFile(fileName: string, path: Path, isDefaultLib: boolean, ignoreNoDefaultLib: boolean, reason: FileIncludeReason, packageId: PackageId | undefined): SourceFile | undefined {
+        function findSourceFile(fileName: string, isDefaultLib: boolean, ignoreNoDefaultLib: boolean, reason: FileIncludeReason, packageId: PackageId | undefined): SourceFile | undefined {
             tracing?.push(tracing.Phase.Program, "findSourceFile", {
                 fileName,
                 isDefaultLib: isDefaultLib || undefined,
                 fileIncludeKind: (FileIncludeKind as any)[reason.kind],
             });
-            const result = findSourceFileWorker(fileName, path, isDefaultLib, ignoreNoDefaultLib, reason, packageId);
+            const result = findSourceFileWorker(fileName, isDefaultLib, ignoreNoDefaultLib, reason, packageId);
             tracing?.pop();
             return result;
         }
 
-        function findSourceFileWorker(fileName: string, path: Path, isDefaultLib: boolean, ignoreNoDefaultLib: boolean, reason: FileIncludeReason, packageId: PackageId | undefined): SourceFile | undefined {
+        function findSourceFileWorker(fileName: string, isDefaultLib: boolean, ignoreNoDefaultLib: boolean, reason: FileIncludeReason, packageId: PackageId | undefined): SourceFile | undefined {
+            const path = toPath(fileName);
             if (useSourceOfProjectReferenceRedirect) {
-                let source = getSourceOfProjectReferenceRedirect(fileName);
+                let source = getSourceOfProjectReferenceRedirect(path);
                 // If preserveSymlinks is true, module resolution wont jump the symlink
                 // but the resolved real path may be the .d.ts from project reference
                 // Note:: Currently we try the real path only if the
@@ -2537,12 +2537,12 @@ namespace ts {
                     options.preserveSymlinks &&
                     isDeclarationFileName(fileName) &&
                     stringContains(fileName, nodeModulesPathPart)) {
-                    const realPath = host.realpath(fileName);
-                    if (realPath !== fileName) source = getSourceOfProjectReferenceRedirect(realPath);
+                    const realPath = toPath(host.realpath(fileName));
+                    if (realPath !== path) source = getSourceOfProjectReferenceRedirect(realPath);
                 }
                 if (source) {
                     const file = isString(source) ?
-                        findSourceFile(source, toPath(source), isDefaultLib, ignoreNoDefaultLib, reason, packageId) :
+                        findSourceFile(source, isDefaultLib, ignoreNoDefaultLib, reason, packageId) :
                         undefined;
                     if (file) addFileToFilesByName(file, path, /*redirectedPath*/ undefined);
                     return file;
@@ -2750,8 +2750,8 @@ namespace ts {
             return ts.forEachResolvedProjectReference(resolvedProjectReferences, cb);
         }
 
-        function getSourceOfProjectReferenceRedirect(file: string) {
-            if (!isDeclarationFileName(file)) return undefined;
+        function getSourceOfProjectReferenceRedirect(path: Path) {
+            if (!isDeclarationFileName(path)) return undefined;
             if (mapFromToProjectReferenceRedirectSource === undefined) {
                 mapFromToProjectReferenceRedirectSource = new Map();
                 forEachResolvedProjectReference(resolvedRef => {
@@ -2772,7 +2772,7 @@ namespace ts {
                     }
                 });
             }
-            return mapFromToProjectReferenceRedirectSource.get(toPath(file));
+            return mapFromToProjectReferenceRedirectSource.get(path);
         }
 
         function isSourceOfProjectReferenceRedirect(fileName: string) {
@@ -2954,10 +2954,8 @@ namespace ts {
                         modulesWithElidedImports.set(file.path, true);
                     }
                     else if (shouldAddFile) {
-                        const path = toPath(resolvedFileName);
                         findSourceFile(
                             resolvedFileName,
-                            path,
                             /*isDefaultLib*/ false,
                             /*ignoreNoDefaultLib*/ false,
                             { kind: FileIncludeKind.Import, file: file.path, index, },
@@ -3691,7 +3689,7 @@ namespace ts {
         useSourceOfProjectReferenceRedirect: boolean;
         toPath(fileName: string): Path;
         getResolvedProjectReferences(): readonly (ResolvedProjectReference | undefined)[] | undefined;
-        getSourceOfProjectReferenceRedirect(fileName: string): SourceOfProjectReferenceRedirect | undefined;
+        getSourceOfProjectReferenceRedirect(path: Path): SourceOfProjectReferenceRedirect | undefined;
         forEachResolvedProjectReference<T>(cb: (resolvedProjectReference: ResolvedProjectReference) => T | undefined): T | undefined;
     }
 
@@ -3778,9 +3776,9 @@ namespace ts {
         }
 
         function fileExistsIfProjectReferenceDts(file: string) {
-            const source = host.getSourceOfProjectReferenceRedirect(file);
+            const source = host.getSourceOfProjectReferenceRedirect(host.toPath(file));
             return source !== undefined ?
-                isString(source) ? originalFileExists.call(host.compilerHost, source) : true :
+                isString(source) ? originalFileExists.call(host.compilerHost, source) as boolean : true :
                 undefined;
         }
 

src/compiler/sys.ts

@@ -1279,7 +1279,7 @@ namespace ts {
 
             const platform: string = _os.platform();
             const useCaseSensitiveFileNames = isFileSystemCaseSensitive();
-            const realpathSync = useCaseSensitiveFileNames ? (_fs.realpathSync.native ?? _fs.realpathSync) : _fs.realpathSync;
+            const realpathSync = _fs.realpathSync.native ?? _fs.realpathSync;
 
             const fsSupportsRecursiveFsWatch = isNode4OrLater && (process.platform === "win32" || process.platform === "darwin");
             const getCurrentDirectory = memoize(() => process.cwd());

src/compiler/types.ts

@@ -6461,6 +6461,7 @@ namespace ts {
         realpath?(path: string): string;
         getCurrentDirectory?(): string;
         getDirectories?(path: string): string[];
+        useCaseSensitiveFileNames?: boolean | (() => boolean);
     }
 
     /**

src/compiler/utilities.ts

@@ -6210,7 +6210,9 @@ namespace ts {
     }
 
     export interface SymlinkedDirectory {
+        /** Matches the casing returned by `realpath`.  Used to compute the `realpath` of children. */
         real: string;
+        /** toPath(real).  Stored to avoid repeated recomputation. */
         realPath: Path;
     }
 

src/harness/harnessLanguageService.ts

@@ -325,7 +325,8 @@ namespace Harness.LanguageService {
                     readFile: fileName => {
                         const scriptInfo = this.getScriptInfo(fileName);
                         return scriptInfo && scriptInfo.content;
-                    }
+                    },
+                    useCaseSensitiveFileNames: this.useCaseSensitiveFileNames()
                 };
                 this.getModuleResolutionsForFile = (fileName) => {
                     const scriptInfo = this.getScriptInfo(fileName)!;

src/server/project.ts

@@ -1706,6 +1706,7 @@ namespace ts.server {
                     readFile: this.projectService.host.readFile.bind(this.projectService.host),
                     getDirectories: this.projectService.host.getDirectories.bind(this.projectService.host),
                     trace: this.projectService.host.trace?.bind(this.projectService.host),
+                    useCaseSensitiveFileNames: this.program.useCaseSensitiveFileNames(),
                 };
             }
             return this.projectService.host;

src/testRunner/unittests/moduleResolution.ts

@@ -65,11 +65,12 @@ namespace ts {
                 fileExists: path => {
                     assert.isTrue(directories.has(getDirectoryPath(path)), `'fileExists' '${path}' request in non-existing directory`);
                     return map.has(path);
-                }
+                },
+                useCaseSensitiveFileNames: true
             };
         }
         else {
-            return { readFile, realpath, fileExists: path => map.has(path) };
+            return { readFile, realpath, fileExists: path => map.has(path), useCaseSensitiveFileNames: true };
         }
         function readFile(path: string): string | undefined {
             const file = map.get(path);

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -3059,6 +3059,7 @@ declare namespace ts {
         realpath?(path: string): string;
         getCurrentDirectory?(): string;
         getDirectories?(path: string): string[];
+        useCaseSensitiveFileNames?: boolean | (() => boolean);
     }
     /**
      * Represents the result of module resolution.

tests/baselines/reference/api/typescript.d.ts

@@ -3059,6 +3059,7 @@ declare namespace ts {
         realpath?(path: string): string;
         getCurrentDirectory?(): string;
         getDirectories?(path: string): string[];
+        useCaseSensitiveFileNames?: boolean | (() => boolean);
     }
     /**
      * Represents the result of module resolution.