Fix document registry cache key calculation for paths compiler option (microsoft#48389)

* Fix document registry cache key calculation for `paths` compiler option

* PR feedback

Author: weswigham

src/services/documentRegistry.ts

@@ -357,7 +357,23 @@ namespace ts {
         };
     }
 
+    function compilerOptionValueToString(value: unknown): string {
+        if (value === null || typeof value !== "object") { // eslint-disable-line no-null/no-null
+            return "" + value;
+        }
+        if (isArray(value)) {
+            return `[${map(value, e => compilerOptionValueToString(e))?.join(",")}]`;
+        }
+        let str = "{";
+        for (const key in value) {
+            if (ts.hasOwnProperty.call(value, key)) { // eslint-disable-line @typescript-eslint/no-unnecessary-qualifier
+                str += `${key}: ${compilerOptionValueToString((value as any)[key])}`;
+            }
+        }
+        return str + "}";
+    }
+
     function getKeyForCompilationSettings(settings: CompilerOptions): DocumentRegistryBucketKey {
-        return sourceFileAffectingCompilerOptions.map(option => getCompilerOptionValue(settings, option)).join("|") as DocumentRegistryBucketKey;
+        return sourceFileAffectingCompilerOptions.map(option => compilerOptionValueToString(getCompilerOptionValue(settings, option))).join("|") + (settings.pathsBasePath ? `|${settings.pathsBasePath}` : undefined) as DocumentRegistryBucketKey;
     }
 }

src/testRunner/unittests/tsserver/languageService.ts

@@ -1,5 +1,5 @@
 namespace ts.projectSystem {
-    describe("unittests:: tsserver:: Language service", () => {
+    describe("unittests:: tsserver:: languageService", () => {
         it("should work correctly on case-sensitive file systems", () => {
             const lib = {
                 path: "/a/Lib/lib.d.ts",
@@ -15,5 +15,54 @@ namespace ts.projectSystem {
             projectService.checkNumberOfProjects({ inferredProjects: 1 });
             projectService.inferredProjects[0].getLanguageService().getProgram();
         });
+
+        it("should support multiple projects with the same file under differing `paths` settings", () => {
+            const files = [
+                {
+                    path: "/project/shared.ts",
+                    content: Utils.dedent`
+                    import {foo_a} from "foo";
+                    `
+                },
+                {
+                    path: `/project/a/tsconfig.json`,
+                    content: `{ "compilerOptions": { "paths": { "foo": ["./foo.d.ts"] } }, "files": ["./index.ts", "./foo.d.ts"] }`
+                },
+                {
+                    path: `/project/a/foo.d.ts`,
+                    content: Utils.dedent`
+                    export const foo_a = 1;
+                    `
+                },
+                {
+                    path: "/project/a/index.ts",
+                    content: `import "../shared";`
+                },
+                {
+                    path: `/project/b/tsconfig.json`,
+                    content: `{ "compilerOptions": { "paths": { "foo": ["./foo.d.ts"] } }, "files": ["./index.ts", "./foo.d.ts"] }`
+                },
+                {
+                    path: `/project/b/foo.d.ts`,
+                    content: Utils.dedent`
+                    export const foo_b = 1;
+                    `
+                },
+                {
+                    path: "/project/b/index.ts",
+                    content: `import "../shared";`
+                }
+            ];
+
+            const host = createServerHost(files, { executingFilePath: "/project/tsc.js", useCaseSensitiveFileNames: true });
+            const projectService = createProjectService(host);
+            projectService.openClientFile(files[3].path);
+            projectService.openClientFile(files[6].path);
+            projectService.checkNumberOfProjects({ configuredProjects: 2 });
+            const proj1Diags = projectService.configuredProjects.get(files[1].path)!.getLanguageService().getProgram()!.getSemanticDiagnostics();
+            Debug.assertEqual(proj1Diags.length, 0);
+            const proj2Diags = projectService.configuredProjects.get(files[4].path)!.getLanguageService().getProgram()!.getSemanticDiagnostics();
+            Debug.assertEqual(proj2Diags.length, 1);
+        });
     });
 }