Allow extending from any

src/compiler/checker.ts

@@ -203,8 +203,6 @@ namespace ts {
         const evolvingArrayTypes: EvolvingArrayType[] = [];
 
         const unknownSymbol = createSymbol(SymbolFlags.Property, "unknown");
-        const untypedModuleSymbol = createSymbol(SymbolFlags.ValueModule, "<untyped>");
-        untypedModuleSymbol.exports = createMap<Symbol>();
         const resolvingSymbol = createSymbol(0, "__resolving__");
 
         const anyType = createIntrinsicType(TypeFlags.Any, "any");
@@ -1253,7 +1251,7 @@ namespace ts {
 
             if (moduleSymbol) {
                 let exportDefaultSymbol: Symbol;
-                if (isUntypedOrShorthandAmbientModuleSymbol(moduleSymbol)) {
+                if (isShorthandAmbientModuleSymbol(moduleSymbol)) {
                     exportDefaultSymbol = moduleSymbol;
                 }
                 else {
@@ -1333,7 +1331,7 @@ namespace ts {
             if (targetSymbol) {
                 const name = specifier.propertyName || specifier.name;
                 if (name.text) {
-                    if (isUntypedOrShorthandAmbientModuleSymbol(moduleSymbol)) {
+                    if (isShorthandAmbientModuleSymbol(moduleSymbol)) {
                         return moduleSymbol;
                     }
 
@@ -1586,18 +1584,15 @@ namespace ts {
                 if (isForAugmentation) {
                     const diag = Diagnostics.Invalid_module_name_in_augmentation_Module_0_resolves_to_an_untyped_module_at_1_which_cannot_be_augmented;
                     error(errorNode, diag, moduleReference, resolvedModule.resolvedFileName);
-                    return undefined;
                 }
                 else if (noImplicitAny && moduleNotFoundError) {
                     error(errorNode,
                         Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type,
                         moduleReference,
                         resolvedModule.resolvedFileName);
-                    return undefined;
                 }
-                // Unlike a failed import, an untyped module produces a dummy symbol.
-                // This is checked for by `isUntypedOrShorthandAmbientModuleSymbol`.
-                return untypedModuleSymbol;
+                // Failed imports and untyped modules are both treated in an untyped manner; only difference is whether we give a diagnostic first.
+                return undefined;
             }
 
             if (moduleNotFoundError) {
@@ -4367,7 +4362,7 @@ namespace ts {
         function getTypeOfFuncClassEnumModule(symbol: Symbol): Type {
             const links = getSymbolLinks(symbol);
             if (!links.type) {
-                if (symbol.flags & SymbolFlags.Module && isUntypedOrShorthandAmbientModuleSymbol(symbol)) {
+                if (symbol.flags & SymbolFlags.Module && isShorthandAmbientModuleSymbol(symbol)) {
                     links.type = anyType;
                 }
                 else {
@@ -22063,7 +22058,7 @@ namespace ts {
 
         function moduleExportsSomeValue(moduleReferenceExpression: Expression): boolean {
             let moduleSymbol = resolveExternalModuleName(moduleReferenceExpression.parent, moduleReferenceExpression);
-            if (!moduleSymbol || isUntypedOrShorthandAmbientModuleSymbol(moduleSymbol)) {
+            if (!moduleSymbol || isShorthandAmbientModuleSymbol(moduleSymbol)) {
                 // If the module is not found or is shorthand, assume that it may export a value.
                 return true;
             }

src/compiler/utilities.ts

@@ -439,8 +439,8 @@ namespace ts {
     }
 
     /** Given a symbol for a module, checks that it is either an untyped import or a shorthand ambient module. */
-    export function isUntypedOrShorthandAmbientModuleSymbol(moduleSymbol: Symbol): boolean {
-        return !moduleSymbol.declarations || isShorthandAmbientModule(moduleSymbol.valueDeclaration);
+    export function isShorthandAmbientModuleSymbol(moduleSymbol: Symbol): boolean {
+        return isShorthandAmbientModule(moduleSymbol.valueDeclaration);
     }
 
     function isShorthandAmbientModule(node: Node): boolean {

src/services/findAllReferences.ts

@@ -187,7 +187,7 @@ namespace ts.FindAllReferences {
                 return { symbol };
             }
 
-            if (ts.isUntypedOrShorthandAmbientModuleSymbol(aliasedSymbol)) {
+            if (ts.isShorthandAmbientModuleSymbol(aliasedSymbol)) {
                 return { symbol, shorthandModuleSymbol: aliasedSymbol };
             }
 

tests/cases/fourslash/untypedModuleImport.ts

@@ -12,7 +12,7 @@ verify.numberOfErrorsInCurrentFile(0);
 
 goTo.marker("fooModule");
 verify.goToDefinitionIs([]);
-verify.quickInfoIs("module <untyped>");
+verify.quickInfoIs("");
 verify.noReferences();
 
 goTo.marker("foo");