Always respect preserveSymlinks

src/compiler/moduleNameResolver.ts

@@ -201,6 +201,37 @@ function resolvedTypeScriptOnly(resolved: Resolved | undefined): PathAndPackageI
     return { fileName: resolved.path, packageId: resolved.packageId };
 }
 
+function createResolvedModuleWithFailedLookupLocationsHandlingSymlink(
+    moduleName: string,
+    resolved: Resolved | undefined,
+    isExternalLibraryImport: boolean | undefined,
+    failedLookupLocations: string[],
+    affectingLocations: string[],
+    diagnostics: Diagnostic[],
+    state: ModuleResolutionState,
+): ResolvedModuleWithFailedLookupLocations {
+    // If this is from node_modules for non relative name, always respect preserveSymlinks
+    if (!state.resultFromCache &&
+        !state.compilerOptions.preserveSymlinks &&
+        resolved &&
+        isExternalLibraryImport &&
+        !resolved.originalPath &&
+        !isExternalModuleNameRelative(moduleName)
+    ) {
+        const { resolvedFileName, originalPath } = getOriginalAndResolvedFileName(resolved.path, state.host, state.traceEnabled);
+        if (originalPath) resolved = { ...resolved, path: resolvedFileName, originalPath };
+    }
+    return createResolvedModuleWithFailedLookupLocations(
+        state.compilerOptions,
+        resolved,
+        isExternalLibraryImport,
+        failedLookupLocations,
+        affectingLocations,
+        diagnostics,
+        state.resultFromCache,
+    );
+}
+
 function createResolvedModuleWithFailedLookupLocations(
     compilerOptions: CompilerOptions,
     resolved: Resolved | undefined,
@@ -436,6 +467,16 @@ function arePathsEqual(path1: string, path2: string, host: ModuleResolutionHost)
     return comparePaths(path1, path2, !useCaseSensitiveFileNames) === Comparison.EqualTo;
 }
 
+function getOriginalAndResolvedFileName(fileName: string, host: ModuleResolutionHost, traceEnabled: boolean) {
+    const resolvedFileName = realPath(fileName, host, traceEnabled);
+    const pathsAreEqual = arePathsEqual(fileName, resolvedFileName, host);
+    return {
+        // If the fileName and realpath are differing only in casing prefer fileName so that we can issue correct errors for casing under forceConsistentCasingInFileNames
+        resolvedFileName: pathsAreEqual ? fileName : resolvedFileName,
+        originalPath: pathsAreEqual ? undefined : fileName,
+    };
+}
+
 /**
  * @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
@@ -526,13 +567,12 @@ export function resolveTypeReferenceDirective(typeReferenceDirectiveName: string
     let resolvedTypeReferenceDirective: ResolvedTypeReferenceDirective | undefined;
     if (resolved) {
         const { fileName, packageId } = resolved;
-        const resolvedFileName = options.preserveSymlinks ? fileName : realPath(fileName, host, traceEnabled);
-        const pathsAreEqual = arePathsEqual(fileName, resolvedFileName, host);
+        let resolvedFileName = fileName, originalPath: string | undefined;
+        if (!options.preserveSymlinks) ({ resolvedFileName, originalPath } = getOriginalAndResolvedFileName(fileName, host, traceEnabled));
         resolvedTypeReferenceDirective = {
             primary,
-            // If the fileName and realpath are differing only in casing prefer fileName so that we can issue correct errors for casing under forceConsistentCasingInFileNames
-            resolvedFileName: pathsAreEqual ? fileName : resolvedFileName,
-            originalPath: pathsAreEqual ? undefined : fileName,
+            resolvedFileName,
+            originalPath,
             packageId,
             isExternalLibraryImport: pathContainsNodeModules(fileName),
         };
@@ -1792,14 +1832,14 @@ function nodeModuleNameResolverWorker(features: NodeResolutionFeatures, moduleNa
         result = tryResolve(extensions);
     }
 
-    return createResolvedModuleWithFailedLookupLocations(
-        compilerOptions,
+    return createResolvedModuleWithFailedLookupLocationsHandlingSymlink(
+        moduleName,
         result?.value?.resolved,
         result?.value?.isExternalLibraryImport,
         failedLookupLocations,
         affectingLocations,
         diagnostics,
-        state.resultFromCache
+        state,
     );
 
     function tryResolve(extensions: Extensions): SearchResult<{ resolved: Resolved, isExternalLibraryImport: boolean }> {
@@ -1823,18 +1863,8 @@ function nodeModuleNameResolverWorker(features: NodeResolutionFeatures, moduleNa
                 }
                 resolved = loadModuleFromNearestNodeModulesDirectory(extensions, moduleName, containingDirectory, state, cache, redirectedReference);
             }
-            if (!resolved) return undefined;
-
-            let resolvedValue = resolved.value;
-            if (!compilerOptions.preserveSymlinks && resolvedValue && !resolvedValue.originalPath) {
-                const path = realPath(resolvedValue.path, host, traceEnabled);
-                const pathsAreEqual = arePathsEqual(path, resolvedValue.path, host);
-                const originalPath = pathsAreEqual ? undefined : resolvedValue.path;
-                // If the path and realpath are differing only in casing prefer path so that we can issue correct errors for casing under forceConsistentCasingInFileNames
-                resolvedValue = { ...resolvedValue, path: pathsAreEqual ? resolvedValue.path : 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.
-            return { value: resolvedValue && { resolved: resolvedValue, isExternalLibraryImport: true } };
+            return resolved && { value: resolved.value && { resolved: resolved.value, isExternalLibraryImport: true } };
         }
         else {
             const { path: candidate, parts } = normalizePathForCJSResolution(containingDirectory, moduleName);
@@ -3061,14 +3091,14 @@ export function classicNameResolver(moduleName: string, containingFile: string,
         tryResolve(Extensions.TypeScript | Extensions.Declaration) ||
         tryResolve(Extensions.JavaScript | (compilerOptions.resolveJsonModule ? Extensions.Json : 0));
     // No originalPath because classic resolution doesn't resolve realPath
-    return createResolvedModuleWithFailedLookupLocations(
-        compilerOptions,
+    return createResolvedModuleWithFailedLookupLocationsHandlingSymlink(
+        moduleName,
         resolved && resolved.value,
         resolved?.value && pathContainsNodeModules(resolved.value.path),
         failedLookupLocations,
         affectingLocations,
         diagnostics,
-        state.resultFromCache
+        state,
     );
 
     function tryResolve(extensions: Extensions): SearchResult<Resolved> {

tests/baselines/reference/moduleResolutionWithExtensions_withPaths.trace.json

@@ -11,6 +11,7 @@
     "File '/node_modules/foo/lib/test.tsx' does not exist.",
     "File '/node_modules/foo/lib/test.d.ts' exist - use it as a name resolution result.",
     "File '/node_modules/foo/package.json' does not exist.",
+    "Resolving real path for '/node_modules/foo/lib/test.d.ts', result '/node_modules/foo/lib/test.d.ts'.",
     "======== Module name 'foo/test.js' was successfully resolved to '/node_modules/foo/lib/test.d.ts'. ========",
     "======== Resolving module 'foo/test' from '/test.ts'. ========",
     "Explicitly specified module resolution kind: 'NodeJs'.",
@@ -23,6 +24,7 @@
     "File '/node_modules/foo/lib/test.tsx' does not exist.",
     "File '/node_modules/foo/lib/test.d.ts' exist - use it as a name resolution result.",
     "File '/node_modules/foo/package.json' does not exist according to earlier cached lookups.",
+    "Resolving real path for '/node_modules/foo/lib/test.d.ts', result '/node_modules/foo/lib/test.d.ts'.",
     "======== Module name 'foo/test' was successfully resolved to '/node_modules/foo/lib/test.d.ts'. ========",
     "======== Resolving module './relative.js' from '/test.ts'. ========",
     "Explicitly specified module resolution kind: 'NodeJs'.",

tests/baselines/reference/moduleResolutionWithSuffixes_one_externalModule_withPaths.trace.json

@@ -13,6 +13,7 @@
     "File '/node_modules/some-library/lib/index.ios.ts' does not exist.",
     "File '/node_modules/some-library/lib/index.ios.tsx' does not exist.",
     "File '/node_modules/some-library/lib/index.ios.d.ts' exist - use it as a name resolution result.",
+    "Resolving real path for '/node_modules/some-library/lib/index.ios.d.ts', result '/node_modules/some-library/lib/index.ios.d.ts'.",
     "======== Module name 'some-library' was successfully resolved to '/node_modules/some-library/lib/index.ios.d.ts'. ========",
     "======== Resolving module 'some-library/index' from '/test.ts'. ========",
     "Explicitly specified module resolution kind: 'NodeJs'.",
@@ -25,6 +26,7 @@
     "File '/node_modules/some-library/lib/index.ios.tsx' does not exist.",
     "File '/node_modules/some-library/lib/index.ios.d.ts' exist - use it as a name resolution result.",
     "File '/node_modules/some-library/package.json' does not exist.",
+    "Resolving real path for '/node_modules/some-library/lib/index.ios.d.ts', result '/node_modules/some-library/lib/index.ios.d.ts'.",
     "======== Module name 'some-library/index' was successfully resolved to '/node_modules/some-library/lib/index.ios.d.ts'. ========",
     "======== Resolving module 'some-library/index.js' from '/test.ts'. ========",
     "Explicitly specified module resolution kind: 'NodeJs'.",
@@ -38,5 +40,6 @@
     "File '/node_modules/some-library/lib/index.ios.tsx' does not exist.",
     "File '/node_modules/some-library/lib/index.ios.d.ts' exist - use it as a name resolution result.",
     "File '/node_modules/some-library/package.json' does not exist according to earlier cached lookups.",
+    "Resolving real path for '/node_modules/some-library/lib/index.ios.d.ts', result '/node_modules/some-library/lib/index.ios.d.ts'.",
     "======== Module name 'some-library/index.js' was successfully resolved to '/node_modules/some-library/lib/index.ios.d.ts'. ========"
 ]

tests/baselines/reference/pathMappingBasedModuleResolution_withExtension_MapedToNodeModules.trace.json

@@ -35,5 +35,6 @@
     "File name '/node_modules/foo/bar/foobar.js' has a '.js' extension - stripping it.",
     "File '/node_modules/foo/bar/foobar.js' exist - use it as a name resolution result.",
     "File '/node_modules/foo/package.json' does not exist according to earlier cached lookups.",
+    "Resolving real path for '/node_modules/foo/bar/foobar.js', result '/node_modules/foo/bar/foobar.js'.",
     "======== Module name 'foo/bar/foobar.js' was successfully resolved to '/node_modules/foo/bar/foobar.js'. ========"
 ]

tests/baselines/reference/requireOfJsonFile_PathMapping.trace.json

@@ -26,5 +26,6 @@
     "File name '/node_modules/foo/bar/foobar.json' has a '.json' extension - stripping it.",
     "File '/node_modules/foo/bar/foobar.json' exist - use it as a name resolution result.",
     "File '/node_modules/foo/package.json' does not exist according to earlier cached lookups.",
+    "Resolving real path for '/node_modules/foo/bar/foobar.json', result '/node_modules/foo/bar/foobar.json'.",
     "======== Module name 'foo/bar/foobar.json' was successfully resolved to '/node_modules/foo/bar/foobar.json'. ========"
 ]

tests/baselines/reference/scopedPackagesClassic.trace.json

@@ -5,5 +5,6 @@
     "File '/node_modules/@types/see__saw/package.json' does not exist.",
     "File '/node_modules/@types/see__saw.d.ts' does not exist.",
     "File '/node_modules/@types/see__saw/index.d.ts' exist - use it as a name resolution result.",
+    "Resolving real path for '/node_modules/@types/see__saw/index.d.ts', result '/node_modules/@types/see__saw/index.d.ts'.",
     "======== Module name '@see/saw' was successfully resolved to '/node_modules/@types/see__saw/index.d.ts'. ========"
 ]

tests/baselines/reference/typingsLookupAmd.trace.json

@@ -14,6 +14,7 @@
     "File '/x/node_modules/@types/b/package.json' does not exist.",
     "File '/x/node_modules/@types/b.d.ts' does not exist.",
     "File '/x/node_modules/@types/b/index.d.ts' exist - use it as a name resolution result.",
+    "Resolving real path for '/x/node_modules/@types/b/index.d.ts', result '/x/node_modules/@types/b/index.d.ts'.",
     "======== Module name 'b' was successfully resolved to '/x/node_modules/@types/b/index.d.ts'. ========",
     "======== Resolving module 'a' from '/x/node_modules/@types/b/index.d.ts'. ========",
     "Module resolution kind is not specified, using 'Classic'.",
@@ -38,6 +39,7 @@
     "File '/node_modules/@types/a/package.json' does not exist.",
     "File '/node_modules/@types/a.d.ts' does not exist.",
     "File '/node_modules/@types/a/index.d.ts' exist - use it as a name resolution result.",
+    "Resolving real path for '/node_modules/@types/a/index.d.ts', result '/node_modules/@types/a/index.d.ts'.",
     "======== Module name 'a' was successfully resolved to '/node_modules/@types/a/index.d.ts'. ========",
     "======== Resolving type reference directive 'a', containing file '/__inferred type names__.ts', root directory '/node_modules/@types'. ========",
     "Resolving with primary search path '/node_modules/@types'.",