Force inclusion of ES6, DOM.Iterable

src/compiler/program.ts

@@ -1821,7 +1821,9 @@ export function createProgram(_rootNamesOrOptions: readonly string[] | CreatePro
             }
             else {
                 forEach(options.lib, (libFileName, index) => {
-                    processRootFile(pathForLibFile(libFileName), /*isDefaultLib*/ true, /*ignoreNoDefaultLib*/ false, { kind: FileIncludeKind.LibFile, index });
+                    for (const p of pathsForLibFile(libFileName)) {
+                        processRootFile(p, /*isDefaultLib*/ true, /*ignoreNoDefaultLib*/ false, { kind: FileIncludeKind.LibFile, index });
+                    }
                 });
             }
         }
@@ -3855,12 +3857,28 @@ export function createProgram(_rootNamesOrOptions: readonly string[] | CreatePro
         }
     }
 
-    function pathForLibFile(libFileName: string): string {
-        const existing = resolvedLibReferences?.get(libFileName);
-        if (existing) return existing.actual;
-        const result = pathForLibFileWorker(libFileName);
-        (resolvedLibReferences ??= new Map()).set(libFileName, result);
-        return result.actual;
+    function pathsForLibFile(libFileName: string): string[] {
+        const names = [libFileName];
+        // Force the inclusion of ES6 and DOM's iterable libs.
+        switch (libFileName) {
+            case "lib.dom.d.ts":
+                names.push("lib.dom.iterable.d.ts");
+                // TODO: auto add dom.asynciterable.d.ts in es2018?
+                break;
+            case "lib.es5.d.ts":
+                names.push("lib.es2015.d.ts");
+                break;
+        }
+
+        return names.map(pathForLibFile);
+
+        function pathForLibFile(libFileName: string): string {
+            const existing = resolvedLibReferences?.get(libFileName);
+            if (existing) return existing.actual;
+            const result = pathForLibFileWorker(libFileName);
+            (resolvedLibReferences ??= new Map()).set(libFileName, result);
+            return result.actual;
+        }
     }
 
     function pathForLibFileWorker(libFileName: string): LibResolution {
@@ -3925,7 +3943,12 @@ export function createProgram(_rootNamesOrOptions: readonly string[] | CreatePro
             const libFileName = getLibFileNameFromLibReference(libReference);
             if (libFileName) {
                 // we ignore any 'no-default-lib' reference set on this file.
-                processRootFile(pathForLibFile(libFileName), /*isDefaultLib*/ true, /*ignoreNoDefaultLib*/ true, { kind: FileIncludeKind.LibReferenceDirective, file: file.path, index });
+                for (const p of pathsForLibFile(libFileName)) {
+                    if (file.fileName === p) {
+                        continue;
+                    }
+                    processRootFile(p, /*isDefaultLib*/ true, /*ignoreNoDefaultLib*/ true, { kind: FileIncludeKind.LibReferenceDirective, file: file.path, index });
+                }
             }
             else {
                 programDiagnostics.addFileProcessingDiagnostic({

src/compiler/utilitiesPublic.ts

@@ -325,22 +325,7 @@ export const targetToLibMap: Map<ScriptTarget, string> = new Map([
 
 export function getDefaultLibFileName(options: CompilerOptions): string {
     const target = getEmitScriptTarget(options);
-    switch (target) {
-        case ScriptTarget.ESNext:
-        case ScriptTarget.ES2024:
-        case ScriptTarget.ES2023:
-        case ScriptTarget.ES2022:
-        case ScriptTarget.ES2021:
-        case ScriptTarget.ES2020:
-        case ScriptTarget.ES2019:
-        case ScriptTarget.ES2018:
-        case ScriptTarget.ES2017:
-        case ScriptTarget.ES2016:
-        case ScriptTarget.ES2015:
-            return targetToLibMap.get(target)!;
-        default:
-            return "lib.d.ts";
-    }
+    return targetToLibMap.get(target) ?? "lib.d.ts";
 }
 
 export function textSpanEnd(span: TextSpan): number {

tests/baselines/reference/ES5For-ofTypeCheck10.errors.txt

@@ -1,8 +1,7 @@
-ES5For-ofTypeCheck10.ts(9,6): error TS2585: 'Symbol' only refers to a type, but is being used as a value here. Do you need to change your target library? Try changing the 'lib' compiler option to es2015 or later.
-ES5For-ofTypeCheck10.ts(14,15): error TS2495: Type 'MyStringIterator' is not an array type or a string type.
+ES5For-ofTypeCheck10.ts(14,15): error TS2802: Type 'MyStringIterator' can only be iterated through when using the '--downlevelIteration' flag or with a '--target' of 'es2015' or higher.
 
 
-==== ES5For-ofTypeCheck10.ts (2 errors) ====
+==== ES5For-ofTypeCheck10.ts (1 errors) ====
     // In ES3/5, you cannot for...of over an arbitrary iterable.
     class MyStringIterator {
         next() {
@@ -12,12 +11,10 @@ ES5For-ofTypeCheck10.ts(14,15): error TS2495: Type 'MyStringIterator' is not an
             };
         }
         [Symbol.iterator]() {
-         ~~~~~~
-!!! error TS2585: 'Symbol' only refers to a type, but is being used as a value here. Do you need to change your target library? Try changing the 'lib' compiler option to es2015 or later.
             return this;
         }
     }
 
     for (var v of new MyStringIterator) { }
                   ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2495: Type 'MyStringIterator' is not an array type or a string type.
+!!! error TS2802: Type 'MyStringIterator' can only be iterated through when using the '--downlevelIteration' flag or with a '--target' of 'es2015' or higher.

tests/baselines/reference/ES5For-ofTypeCheck10.symbols

@@ -19,6 +19,9 @@ class MyStringIterator {
     }
     [Symbol.iterator]() {
 >[Symbol.iterator] : Symbol(MyStringIterator[Symbol.iterator], Decl(ES5For-ofTypeCheck10.ts, 7, 5))
+>Symbol.iterator : Symbol(SymbolConstructor.iterator, Decl(lib.es2015.iterable.d.ts, --, --))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
+>iterator : Symbol(SymbolConstructor.iterator, Decl(lib.es2015.iterable.d.ts, --, --))
 
         return this;
 >this : Symbol(MyStringIterator, Decl(ES5For-ofTypeCheck10.ts, 0, 0))

tests/baselines/reference/ES5For-ofTypeCheck10.types

@@ -31,12 +31,12 @@ class MyStringIterator {
     [Symbol.iterator]() {
 >[Symbol.iterator] : () => this
 >                  : ^^^^^^^^^^
->Symbol.iterator : any
->                : ^^^
->Symbol : any
->       : ^^^
->iterator : any
->         : ^^^
+>Symbol.iterator : unique symbol
+>                : ^^^^^^^^^^^^^
+>Symbol : SymbolConstructor
+>       : ^^^^^^^^^^^^^^^^^
+>iterator : unique symbol
+>         : ^^^^^^^^^^^^^
 
         return this;
 >this : this

tests/baselines/reference/ES5SymbolProperty1.symbols

@@ -2,28 +2,28 @@
 
 === ES5SymbolProperty1.ts ===
 interface SymbolConstructor {
->SymbolConstructor : Symbol(SymbolConstructor, Decl(ES5SymbolProperty1.ts, 0, 0))
+>SymbolConstructor : Symbol(SymbolConstructor, Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(ES5SymbolProperty1.ts, 0, 0))
 
     foo: string;
 >foo : Symbol(SymbolConstructor.foo, Decl(ES5SymbolProperty1.ts, 0, 29))
 }
 var Symbol: SymbolConstructor;
->Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(ES5SymbolProperty1.ts, 3, 3))
->SymbolConstructor : Symbol(SymbolConstructor, Decl(ES5SymbolProperty1.ts, 0, 0))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(ES5SymbolProperty1.ts, 3, 3))
+>SymbolConstructor : Symbol(SymbolConstructor, Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(ES5SymbolProperty1.ts, 0, 0))
 
 var obj = {
 >obj : Symbol(obj, Decl(ES5SymbolProperty1.ts, 5, 3))
 
     [Symbol.foo]: 0
 >[Symbol.foo] : Symbol([Symbol.foo], Decl(ES5SymbolProperty1.ts, 5, 11))
 >Symbol.foo : Symbol(SymbolConstructor.foo, Decl(ES5SymbolProperty1.ts, 0, 29))
->Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(ES5SymbolProperty1.ts, 3, 3))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(ES5SymbolProperty1.ts, 3, 3))
 >foo : Symbol(SymbolConstructor.foo, Decl(ES5SymbolProperty1.ts, 0, 29))
 }
 
 obj[Symbol.foo];
 >obj : Symbol(obj, Decl(ES5SymbolProperty1.ts, 5, 3))
 >Symbol.foo : Symbol(SymbolConstructor.foo, Decl(ES5SymbolProperty1.ts, 0, 29))
->Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(ES5SymbolProperty1.ts, 3, 3))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(ES5SymbolProperty1.ts, 3, 3))
 >foo : Symbol(SymbolConstructor.foo, Decl(ES5SymbolProperty1.ts, 0, 29))
 

tests/baselines/reference/ES5SymbolProperty2.symbols

@@ -23,4 +23,7 @@ module M {
 >M.C : Symbol(M.C, Decl(ES5SymbolProperty2.ts, 1, 20))
 >M : Symbol(M, Decl(ES5SymbolProperty2.ts, 0, 0))
 >C : Symbol(M.C, Decl(ES5SymbolProperty2.ts, 1, 20))
+>Symbol.iterator : Symbol(SymbolConstructor.iterator, Decl(lib.es2015.iterable.d.ts, --, --))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
+>iterator : Symbol(SymbolConstructor.iterator, Decl(lib.es2015.iterable.d.ts, --, --))
 

tests/baselines/reference/ES5SymbolProperty2.types

@@ -7,7 +7,6 @@ module M {
 
     var Symbol: any;
 >Symbol : any
->       : ^^^
 
     export class C {
 >C : C
@@ -17,7 +16,6 @@ module M {
 >[Symbol.iterator] : () => void
 >                  : ^^^^^^^^^^
 >Symbol.iterator : any
->                : ^^^
 >Symbol : any
 >       : ^^^
 >iterator : any
@@ -33,16 +31,14 @@ module M {
 >C : typeof C
 >  : ^^^^^^^^
 >Symbol.iterator : any
->                : ^^^
 >Symbol : any
 >       : ^^^
 >iterator : any
 >         : ^^^
 }
 
 (new M.C)[Symbol.iterator];
->(new M.C)[Symbol.iterator] : () => void
->                           : ^^^^^^^^^^
+>(new M.C)[Symbol.iterator] : error
 >(new M.C) : M.C
 >          : ^^^
 >new M.C : M.C
@@ -53,10 +49,10 @@ module M {
 >  : ^^^^^^^^
 >C : typeof M.C
 >  : ^^^^^^^^^^
->Symbol.iterator : any
->                : ^^^
->Symbol : any
->       : ^^^
->iterator : any
->         : ^^^
+>Symbol.iterator : unique symbol
+>                : ^^^^^^^^^^^^^
+>Symbol : SymbolConstructor
+>       : ^^^^^^^^^^^^^^^^^
+>iterator : unique symbol
+>         : ^^^^^^^^^^^^^
 

tests/baselines/reference/ES5SymbolProperty3.errors.txt

@@ -0,0 +1,14 @@
+ES5SymbolProperty3.ts(1,5): error TS2403: Subsequent variable declarations must have the same type.  Variable 'Symbol' must be of type 'SymbolConstructor', but here has type 'any'.
+
+
+==== ES5SymbolProperty3.ts (1 errors) ====
+    var Symbol: any;
+        ~~~~~~
+!!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Symbol' must be of type 'SymbolConstructor', but here has type 'any'.
+!!! related TS6203 lib.es2015.symbol.d.ts:--:--: 'Symbol' was also declared here.
+
+    class C {
+        [Symbol.iterator]() { }
+    }
+
+    (new C)[Symbol.iterator]

tests/baselines/reference/ES5SymbolProperty3.symbols

@@ -2,17 +2,21 @@
 
 === ES5SymbolProperty3.ts ===
 var Symbol: any;
->Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(ES5SymbolProperty3.ts, 0, 3))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(ES5SymbolProperty3.ts, 0, 3))
 
 class C {
 >C : Symbol(C, Decl(ES5SymbolProperty3.ts, 0, 16))
 
     [Symbol.iterator]() { }
 >[Symbol.iterator] : Symbol(C[Symbol.iterator], Decl(ES5SymbolProperty3.ts, 2, 9))
->Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(ES5SymbolProperty3.ts, 0, 3))
+>Symbol.iterator : Symbol(SymbolConstructor.iterator, Decl(lib.es2015.iterable.d.ts, --, --))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(ES5SymbolProperty3.ts, 0, 3))
+>iterator : Symbol(SymbolConstructor.iterator, Decl(lib.es2015.iterable.d.ts, --, --))
 }
 
 (new C)[Symbol.iterator]
 >C : Symbol(C, Decl(ES5SymbolProperty3.ts, 0, 16))
->Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(ES5SymbolProperty3.ts, 0, 3))
+>Symbol.iterator : Symbol(SymbolConstructor.iterator, Decl(lib.es2015.iterable.d.ts, --, --))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(ES5SymbolProperty3.ts, 0, 3))
+>iterator : Symbol(SymbolConstructor.iterator, Decl(lib.es2015.iterable.d.ts, --, --))
 

tests/baselines/reference/ES5SymbolProperty3.types

@@ -2,7 +2,8 @@
 
 === ES5SymbolProperty3.ts ===
 var Symbol: any;
->Symbol : any
+>Symbol : SymbolConstructor
+>       : ^^^^^^^^^^^^^^^^^
 
 class C {
 >C : C
@@ -11,11 +12,12 @@ class C {
     [Symbol.iterator]() { }
 >[Symbol.iterator] : () => void
 >                  : ^^^^^^^^^^
->Symbol.iterator : any
->Symbol : any
->       : ^^^
->iterator : any
->         : ^^^
+>Symbol.iterator : unique symbol
+>                : ^^^^^^^^^^^^^
+>Symbol : SymbolConstructor
+>       : ^^^^^^^^^^^^^^^^^
+>iterator : unique symbol
+>         : ^^^^^^^^^^^^^
 }
 
 (new C)[Symbol.iterator]
@@ -27,9 +29,10 @@ class C {
 >      : ^
 >C : typeof C
 >  : ^^^^^^^^
->Symbol.iterator : any
->Symbol : any
->       : ^^^
->iterator : any
->         : ^^^
+>Symbol.iterator : unique symbol
+>                : ^^^^^^^^^^^^^
+>Symbol : SymbolConstructor
+>       : ^^^^^^^^^^^^^^^^^
+>iterator : unique symbol
+>         : ^^^^^^^^^^^^^
 

tests/baselines/reference/ES5SymbolProperty4.errors.txt

@@ -0,0 +1,14 @@
+ES5SymbolProperty4.ts(1,5): error TS2403: Subsequent variable declarations must have the same type.  Variable 'Symbol' must be of type 'SymbolConstructor', but here has type '{ iterator: string; }'.
+
+
+==== ES5SymbolProperty4.ts (1 errors) ====
+    var Symbol: { iterator: string };
+        ~~~~~~
+!!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Symbol' must be of type 'SymbolConstructor', but here has type '{ iterator: string; }'.
+!!! related TS6203 lib.es2015.symbol.d.ts:--:--: 'Symbol' was also declared here.
+
+    class C {
+        [Symbol.iterator]() { }
+    }
+
+    (new C)[Symbol.iterator]

tests/baselines/reference/ES5SymbolProperty4.symbols

@@ -2,22 +2,22 @@
 
 === ES5SymbolProperty4.ts ===
 var Symbol: { iterator: string };
->Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(ES5SymbolProperty4.ts, 0, 3))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(ES5SymbolProperty4.ts, 0, 3))
 >iterator : Symbol(iterator, Decl(ES5SymbolProperty4.ts, 0, 13))
 
 class C {
 >C : Symbol(C, Decl(ES5SymbolProperty4.ts, 0, 33))
 
     [Symbol.iterator]() { }
 >[Symbol.iterator] : Symbol(C[Symbol.iterator], Decl(ES5SymbolProperty4.ts, 2, 9))
->Symbol.iterator : Symbol(iterator, Decl(ES5SymbolProperty4.ts, 0, 13))
->Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(ES5SymbolProperty4.ts, 0, 3))
->iterator : Symbol(iterator, Decl(ES5SymbolProperty4.ts, 0, 13))
+>Symbol.iterator : Symbol(SymbolConstructor.iterator, Decl(lib.es2015.iterable.d.ts, --, --))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(ES5SymbolProperty4.ts, 0, 3))
+>iterator : Symbol(SymbolConstructor.iterator, Decl(lib.es2015.iterable.d.ts, --, --))
 }
 
 (new C)[Symbol.iterator]
 >C : Symbol(C, Decl(ES5SymbolProperty4.ts, 0, 33))
->Symbol.iterator : Symbol(iterator, Decl(ES5SymbolProperty4.ts, 0, 13))
->Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(ES5SymbolProperty4.ts, 0, 3))
->iterator : Symbol(iterator, Decl(ES5SymbolProperty4.ts, 0, 13))
+>Symbol.iterator : Symbol(SymbolConstructor.iterator, Decl(lib.es2015.iterable.d.ts, --, --))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(ES5SymbolProperty4.ts, 0, 3))
+>iterator : Symbol(SymbolConstructor.iterator, Decl(lib.es2015.iterable.d.ts, --, --))