Merge pull request #41507 from microsoft/fix32890

Fix definition of ts.Iterator

Author: rbuckton

package-lock.json

@@ -88,7 +88,7 @@ namespace ts {
 
     /** ES6 Iterator type. */
     export interface Iterator<T> {
-        next(): { value: T, done?: false } | { value: never, done: true };
+        next(): { value: T, done?: false } | { value: void, done: true };
     }
 
     /** Array that is only intended to be pushed to, never read. */

src/compiler/corePublic.ts

@@ -621,8 +621,9 @@ namespace ts {
             const invokeMap = new Map<Path, string[]>();
 
             while (!timerToUpdateChildWatches && cacheToUpdateChildWatches.size) {
-                const { value: [dirPath, { dirName, options, fileNames }], done } = cacheToUpdateChildWatches.entries().next();
-                Debug.assert(!done);
+                const result = cacheToUpdateChildWatches.entries().next();
+                Debug.assert(!result.done);
+                const { value: [dirPath, { dirName, options, fileNames }] } = result;
                 cacheToUpdateChildWatches.delete(dirPath);
                 // Because the child refresh is fresh, we would need to invalidate whole root directory being watched
                 // to ensure that all the changes are reflected at this time

src/compiler/sys.ts

@@ -9,7 +9,7 @@ namespace ts {
 
     type IteratorResultShim<T> =
         | { value: T, done?: false }
-        | { value: never, done: true };
+        | { value: void, done: true };
 
     interface IteratorShim<T> {
         next(): IteratorResultShim<T>;

src/shims/collectionShims.ts

@@ -189,8 +189,9 @@ interface Symbol {
     export function generateSourceMapBaselineFiles(sys: System & { writtenFiles: ReadonlyCollection<string>; }) {
         const mapFileNames = mapDefinedIterator(sys.writtenFiles.keys(), f => f.endsWith(".map") ? f : undefined);
         while (true) {
-            const { value: mapFile, done } = mapFileNames.next();
-            if (done) break;
+            const result = mapFileNames.next();
+            if (result.done) break;
+            const mapFile = result.value;
             const text = Harness.SourceMapRecorder.getSourceMapRecordWithSystem(sys, mapFile);
             sys.writeFile(`${mapFile}.baseline.txt`, text);
         }

src/testRunner/unittests/tsbuild/helpers.ts

@@ -81,7 +81,7 @@ declare namespace ts {
             value: T;
             done?: false;
         } | {
-            value: never;
+            value: void;
             done: true;
         };
     }

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

@@ -81,7 +81,7 @@ declare namespace ts {
             value: T;
             done?: false;
         } | {
-            value: never;
+            value: void;
             done: true;
         };
     }