Fix bug: Resolve module symbol before checking whether module export is a re-export (#20989)

* Fix bug: Resolve module symbol before checking whether module export is a re-export

* Remove unnecessary @nolib

Author: Andy

src/compiler/checker.ts

@@ -273,6 +273,7 @@ namespace ts {
             },
             getJsxNamespace: () => unescapeLeadingUnderscores(getJsxNamespace()),
             getAccessibleSymbolChain,
+            resolveExternalModuleSymbol,
         };
 
         const tupleTypes: GenericType[] = [];

src/compiler/types.ts

@@ -2874,6 +2874,8 @@ namespace ts {
          * This should be called in a loop climbing parents of the symbol, so we'll get `N`.
          */
         /* @internal */ getAccessibleSymbolChain(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, useOnlyExternalAliasing: boolean): Symbol[] | undefined;
+
+        /* @internal */ resolveExternalModuleSymbol(symbol: Symbol): Symbol;
     }
 
     /* @internal */

src/services/completions.ts

@@ -1155,9 +1155,10 @@ namespace ts.Completions {
             codefix.forEachExternalModuleToImportFrom(typeChecker, sourceFile, allSourceFiles, moduleSymbol => {
                 for (let symbol of typeChecker.getExportsOfModule(moduleSymbol)) {
                     // Don't add a completion for a re-export, only for the original.
-                    // If `symbol.parent !== moduleSymbol`, this comes from an `export * from "foo"` re-export. Those don't create new symbols.
+                    // If `symbol.parent !== ...`, this comes from an `export * from "foo"` re-export. Those don't create new symbols.
                     // If `some(...)`, this comes from an `export { foo } from "foo"` re-export, which creates a new symbol (thus isn't caught by the first check).
-                    if (symbol.parent !== moduleSymbol || some(symbol.declarations, d => isExportSpecifier(d) && !!d.parent.parent.moduleSpecifier)) {
+                    if (symbol.parent !== typeChecker.resolveExternalModuleSymbol(moduleSymbol)
+                        || some(symbol.declarations, d => isExportSpecifier(d) && !!d.parent.parent.moduleSpecifier)) {
                         continue;
                     }
 

tests/cases/fourslash/completionsImport_named_exportEqualsNamespace.ts

@@ -0,0 +1,26 @@
+/// <reference path="fourslash.ts" />
+
+// @Filename: /a.d.ts
+////declare namespace N {
+////    export const foo = 0;
+////}
+////export = N;
+
+// @Filename: /b.ts
+////f/**/;
+
+goTo.marker("");
+verify.completionListContains({ name: "foo", source: "/a" }, "const N.foo: 0", "", "const", /*spanIndex*/ undefined, /*hasAction*/ true, {
+    includeExternalModuleExports: true,
+    sourceDisplay: "./a",
+});
+
+verify.applyCodeActionFromCompletion("", {
+    name: "foo",
+    source: "/a",
+    description: `Import 'foo' from module "./a"`,
+    // TODO: GH#18445
+    newFileContent: `import { foo } from "./a";\r
+\r
+f;`,
+});