Set hasAddedOrRemovedSymlinks when discovering an existing file by its link

src/compiler/program.ts

@@ -1674,8 +1674,8 @@ namespace ts {
                 const typesReferenceDirectives = map(newSourceFile.typeReferenceDirectives, ref => toFileNameLowerCase(ref.fileName));
                 const typeReferenceResolutions = resolveTypeReferenceDirectiveNamesWorker(typesReferenceDirectives, newSourceFile);
                 // ensure that types resolutions are still correct
-                const typeReferenceEesolutionsChanged = hasChangesInResolutions(typesReferenceDirectives, typeReferenceResolutions, oldSourceFile.resolvedTypeReferenceDirectiveNames, oldSourceFile, typeDirectiveIsEqualTo);
-                if (typeReferenceEesolutionsChanged) {
+                const typeReferenceResolutionsChanged = hasChangesInResolutions(typesReferenceDirectives, typeReferenceResolutions, oldSourceFile.resolvedTypeReferenceDirectiveNames, oldSourceFile, typeDirectiveIsEqualTo);
+                if (typeReferenceResolutionsChanged) {
                     structureIsReused = StructureIsReused.SafeModules;
                     newSourceFile.resolvedTypeReferenceDirectiveNames = zipToModeAwareCache(newSourceFile, typesReferenceDirectives, typeReferenceResolutions);
                 }

src/compiler/resolutionCache.ts

@@ -66,6 +66,7 @@ namespace ts {
         getCurrentProgram(): Program | undefined;
         fileIsOpen(filePath: Path): boolean;
         getCompilerHost?(): CompilerHost | undefined;
+        onDiscoveredSymlink?(): void;
     }
 
     interface DirectoryWatchesOfFailedLookup {
@@ -431,6 +432,9 @@ namespace ts {
                     else {
                         resolution = loader(name, containingFile, compilerOptions, resolutionHost.getCompilerHost?.() || resolutionHost, redirectedReference, containingSourceFile);
                         perDirectoryResolution.set(name, mode, resolution);
+                        if (resolutionHost.onDiscoveredSymlink && resolutionIsSymlink(resolution)) {
+                            resolutionHost.onDiscoveredSymlink();
+                        }
                     }
                     resolutionsInFile.set(name, mode, resolution);
                     watchFailedLookupLocationsOfExternalModuleResolutions(name, resolution, path, getResolutionWithResolvedFileName);
@@ -965,4 +969,11 @@ namespace ts {
             return dirPath === rootPath || canWatchDirectory(dirPath);
         }
     }
+
+    function resolutionIsSymlink(resolution: ResolutionWithFailedLookupLocations) {
+        return !!(
+            (resolution as ResolvedModuleWithFailedLookupLocations).resolvedModule?.originalPath ||
+            (resolution as ResolvedTypeReferenceDirectiveWithFailedLookupLocations).resolvedTypeReferenceDirective?.originalPath
+        );
+    }
 }

src/server/project.ts

@@ -1031,6 +1031,11 @@ namespace ts.server {
             }
         }
 
+        /* @internal */
+        onDiscoveredSymlink() {
+            this.hasAddedOrRemovedSymlinks = true;
+        }
+
         /**
          * Updates set of files that contribute to this project
          * @returns: true if set of files in the project stays the same and false - otherwise.

tests/cases/fourslash/server/completionsImport_addToNamedWithDifferentCacheValue.ts

@@ -0,0 +1,87 @@
+/// <reference path="../fourslash.ts" />
+
+// Notable lack of package.json referencing `mylib` as dependency here.
+// This is not accurate to the original repro, but I think that's a separate
+// bug, which, if fixed, would prevent the later crash.
+
+// @Filename: /tsconfig.json
+//// { "compilerOptions": { "module": "commonjs" } }
+
+// @Filename: /packages/mylib/package.json
+//// { "name": "mylib", "version": "1.0.0", "main": "index.js" }
+
+// @Filename: /packages/mylib/index.ts
+//// export * from "./mySubDir";
+
+// @Filename: /packages/mylib/mySubDir/index.ts
+//// export * from "./myClass";
+//// export * from "./myClass2";
+
+// @Filename: /packages/mylib/mySubDir/myClass.ts
+//// export class MyClass {}
+
+// @Filename: /packages/mylib/mySubDir/myClass2.ts
+//// export class MyClass2 {}
+
+// @link: /packages/mylib -> /node_modules/mylib
+
+// @Filename: /src/index.ts
+//// 
+//// const a = new MyClass/*1*/();
+//// const b = new MyClass2/*2*/();
+
+goTo.marker("1");
+format.setOption("newLineCharacter", "\n");
+
+verify.completions({
+  marker: "1",
+  includes: [{
+    name: "MyClass",
+    source: "../packages/mylib",
+    sourceDisplay: "../packages/mylib",
+    hasAction: true,
+    sortText: completion.SortText.AutoImportSuggestions,
+  }],
+  preferences: {
+    includeCompletionsForModuleExports: true,
+    includeInsertTextCompletions: true,
+    allowIncompleteCompletions: true,
+  }
+});
+
+verify.applyCodeActionFromCompletion("1", {
+  name: "MyClass",
+  source: "../packages/mylib",
+  description: `Import 'MyClass' from module "../packages/mylib"`,
+  data: {
+    exportName: "MyClass",
+    fileName: "/packages/mylib/index.ts",
+  },
+  preferences: {
+    includeCompletionsForModuleExports: true,
+    includeCompletionsWithInsertText: true,
+    allowIncompleteCompletions: true,
+  },
+  newFileContent: `import { MyClass } from "../packages/mylib";
+
+const a = new MyClass();
+const b = new MyClass2();`,
+});
+
+edit.replaceLine(0, `import { MyClass } from "mylib";`);
+
+verify.completions({
+  marker: "2",
+  includes: [{
+    name: "MyClass2",
+    source: "mylib",
+    sourceDisplay: "mylib",
+    hasAction: true,
+    sortText: completion.SortText.AutoImportSuggestions,
+  }],
+  preferences: {
+    includeCompletionsForModuleExports: true,
+    includeInsertTextCompletions: true,
+    allowIncompleteCompletions: true,
+  }
+});