microsoft · jakebailey · Aug 10, 2022 · Jul 26, 2022
diff --git a/Gulpfile.js b/Gulpfile.js
@@ -92,18 +92,12 @@ const localize = async () => {
    }
 };

-const buildShims = () => buildProject("src/shims");
-const cleanShims = () => cleanProject("src/shims");
-cleanTasks.push(cleanShims);
-
 const buildDebugTools = () => buildProject("src/debug");
 const cleanDebugTools = () => cleanProject("src/debug");
 cleanTasks.push(cleanDebugTools);

-const buildShimsAndTools = parallel(buildShims, buildDebugTools);
-
 // Pre-build steps when targeting the LKG compiler
-const lkgPreBuild = parallel(generateLibs, series(buildScripts, generateDiagnostics, buildShimsAndTools));
+const lkgPreBuild = parallel(generateLibs, series(buildScripts, generateDiagnostics, buildDebugTools));

 const buildTsc = () => buildProject("src/tsc");
 task("tsc", series(lkgPreBuild, buildTsc));
@@ -119,7 +113,7 @@ task("watch-tsc", series(lkgPreBuild, parallel(watchLib, watchDiagnostics, watch
 task("watch-tsc").description = "Watch for changes and rebuild the command-line compiler only.";

 // Pre-build steps when targeting the built/local compiler.
-const localPreBuild = parallel(generateLibs, series(buildScripts, generateDiagnostics, buildShimsAndTools, buildTsc));
+const localPreBuild = parallel(generateLibs, series(buildScripts, generateDiagnostics, buildDebugTools, buildTsc));

 // Pre-build steps to use based on supplied options.
 const preBuild = cmdLineOptions.lkg ? lkgPreBuild : localPreBuild;

diff --git a/src/compiler/corePublic.ts b/src/compiler/corePublic.ts
@@ -124,45 +124,34 @@ namespace ts {
        /**
         * Returns the native Map implementation if it is available and compatible (i.e. supports iteration).
         */
-        export function tryGetNativeMap(): MapConstructor | undefined {
+        export function tryGetNativeMap(): MapConstructor {
            // Internet Explorer's Map doesn't support iteration, so don't use it.
            const gMap = globals?.Map;
            // eslint-disable-next-line no-in-operator
-            return typeof gMap !== "undefined" && "entries" in gMap.prototype && new gMap([[0, 0]]).size === 1 ? gMap : undefined;
+            const constructor = typeof gMap !== "undefined" && "entries" in gMap.prototype && new gMap([[0, 0]]).size === 1 ? gMap : undefined;
+            if (!constructor) {
+                throw new Error("No compatible Map implementation found.");
+            }
+            return constructor;
        }

        /**
         * Returns the native Set implementation if it is available and compatible (i.e. supports iteration).
         */
-        export function tryGetNativeSet(): SetConstructor | undefined {
+        export function tryGetNativeSet(): SetConstructor {
            // Internet Explorer's Set doesn't support iteration, so don't use it.
            const gSet = globals?.Set;
            // eslint-disable-next-line no-in-operator
-            return typeof gSet !== "undefined" && "entries" in gSet.prototype && new gSet([0]).size === 1 ? gSet : undefined;
+            const constructor = typeof gSet !== "undefined" && "entries" in gSet.prototype && new gSet([0]).size === 1 ? gSet : undefined;
+            if (!constructor) {
+                throw new Error("No compatible Set implementation found.");
+            }
+            return constructor;
        }
    }

    /* @internal */
-    export const Map = getCollectionImplementation("Map", "tryGetNativeMap", "createMapShim");
+    export const Map = NativeCollections.tryGetNativeMap();
    /* @internal */
-    export const Set = getCollectionImplementation("Set", "tryGetNativeSet", "createSetShim");
-
-    /* @internal */
-    type GetIteratorCallback = <I extends readonly any[] | ReadonlySet<any> | ReadonlyESMap<any, any> | undefined>(iterable: I) => Iterator<
-        I extends ReadonlyESMap<infer K, infer V> ? [K, V] :
-        I extends ReadonlySet<infer T> ? T :
-        I extends readonly (infer T)[] ? T :
-        I extends undefined ? undefined :
-        never>;
-
-    /* @internal */
-    function getCollectionImplementation<
-        K1 extends MatchingKeys<typeof NativeCollections, () => any>,
-        K2 extends MatchingKeys<typeof ShimCollections, (getIterator?: GetIteratorCallback) => ReturnType<(typeof NativeCollections)[K1]>>
-    >(name: string, nativeFactory: K1, shimFactory: K2): NonNullable<ReturnType<(typeof NativeCollections)[K1]>> {
-        // NOTE: ts.ShimCollections will be defined for typescriptServices.js but not for tsc.js, so we must test for it.
-        const constructor = NativeCollections[nativeFactory]() ?? ShimCollections?.[shimFactory](getIterator);
-        if (constructor) return constructor as NonNullable<ReturnType<(typeof NativeCollections)[K1]>>;
-        throw new Error(`TypeScript requires an environment that provides a compatible native ${name} implementation.`);
-    }
+    export const Set = NativeCollections.tryGetNativeSet();
 }
diff --git a/src/compiler/tsconfig.json b/src/compiler/tsconfig.json
@@ -6,7 +6,6 @@
    },

    "references": [
-        { "path": "../shims" }
    ],

    "files": [

diff --git a/src/compiler/tsconfig.release.json b/src/compiler/tsconfig.release.json
@@ -6,6 +6,5 @@
        "preserveConstEnums": false
    },
    "references": [
-        { "path": "../shims" }
    ]
 }
diff --git a/src/services/tsconfig.json b/src/services/tsconfig.json
@@ -4,7 +4,6 @@
        "outFile": "../../built/local/services.js"
    },
    "references": [
-        { "path": "../shims" },
        { "path": "../compiler" },
        { "path": "../jsTyping" }
    ],

diff --git a/src/shims/collectionShims.ts b/src/shims/collectionShims.ts
diff --git a/src/shims/tsconfig.json b/src/shims/tsconfig.json