Elide re-exports of unresolved type-only imports (microsoft#56449)

Author: andrewbranch

src/compiler/checker.ts

@@ -47581,7 +47581,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
  }
  const target = getExportSymbolOfValueSymbolIfExported(resolveAlias(symbol));
  if (target === unknownSymbol) {
- return true;
+ return !excludeTypeOnlyValues || !getTypeOnlyAliasDeclaration(symbol);
  }
  // const enums and modules that contain only const enums are not considered values from the emit perspective
  // unless 'preserveConstEnums' option is set to true

src/testRunner/unittests/services/transpile.ts

@@ -662,4 +662,15 @@ export * as alias from './file';`,
  testVerbatimModuleSyntax: true,
  },
  );
+
+ transpilesCorrectly(
+ "Elides re-export of type-only import",
+ `
+ import type { Foo } from "./types";
+ export { Foo };
+ `,
+ {
+ options: { compilerOptions: { module: ts.ModuleKind.ESNext, target: ts.ScriptTarget.ESNext } },
+ },
+ );
 });