Allow export default interface. Related to issue 3792. (#16040)

* Allow export default interface. Related to issue 3792.

* Update exportDefaultAbstractClass test

* Allow default export to be a non-value for lookup purposes

* Add local usage to exportDefaultInterface test

src/compiler/parser.ts

@@ -1240,12 +1240,12 @@ namespace ts {
             if (token() === SyntaxKind.ExportKeyword) {
                 nextToken();
                 if (token() === SyntaxKind.DefaultKeyword) {
-                    return lookAhead(nextTokenIsClassOrFunctionOrAsync);
+                    return lookAhead(nextTokenCanFollowDefaultKeyword);
                 }
                 return token() !== SyntaxKind.AsteriskToken && token() !== SyntaxKind.AsKeyword && token() !== SyntaxKind.OpenBraceToken && canFollowModifier();
             }
             if (token() === SyntaxKind.DefaultKeyword) {
-                return nextTokenIsClassOrFunctionOrAsync();
+                return nextTokenCanFollowDefaultKeyword();
             }
             if (token() === SyntaxKind.StaticKeyword) {
                 nextToken();
@@ -1267,9 +1267,10 @@ namespace ts {
                 || isLiteralPropertyName();
         }
 
-        function nextTokenIsClassOrFunctionOrAsync(): boolean {
+        function nextTokenCanFollowDefaultKeyword(): boolean {
             nextToken();
             return token() === SyntaxKind.ClassKeyword || token() === SyntaxKind.FunctionKeyword ||
+                token() === SyntaxKind.InterfaceKeyword ||
                 (token() === SyntaxKind.AbstractKeyword && lookAhead(nextTokenIsClassKeywordOnSameLine)) ||
                 (token() === SyntaxKind.AsyncKeyword && lookAhead(nextTokenIsFunctionKeywordOnSameLine));
         }

src/compiler/utilities.ts

@@ -3168,11 +3168,11 @@ namespace ts {
     }
 
     export function getLocalSymbolForExportDefault(symbol: Symbol) {
-        return isExportDefaultSymbol(symbol) ? symbol.valueDeclaration.localSymbol : undefined;
+        return isExportDefaultSymbol(symbol) ? symbol.declarations[0].localSymbol : undefined;
     }
 
     function isExportDefaultSymbol(symbol: Symbol): boolean {
-        return symbol && symbol.valueDeclaration && hasModifier(symbol.valueDeclaration, ModifierFlags.Default);
+        return symbol && length(symbol.declarations) > 0 && hasModifier(symbol.declarations[0], ModifierFlags.Default);
     }
 
     /** Return ".ts", ".d.ts", or ".tsx", if that is the extension. */

tests/baselines/reference/exportDefaultAbstractClass.js

@@ -1,14 +1,29 @@
 //// [tests/cases/compiler/exportDefaultAbstractClass.ts] ////
 
 //// [a.ts]
-export default abstract class A {}
+export default abstract class A { a: number; }
+
+class B extends A {}
+new B().a.toExponential();
 
 //// [b.ts]
-import A from './a'
-
+import A from './a';
+
+class C extends A {}
+new C().a.toExponential();
 
 //// [a.js]
 "use strict";
+var __extends = (this && this.__extends) || (function () {
+    var extendStatics = Object.setPrototypeOf ||
+        ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
+        function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
+    return function (d, b) {
+        extendStatics(d, b);
+        function __() { this.constructor = d; }
+        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
+    };
+})();
 exports.__esModule = true;
 var A = (function () {
     function A() {
@@ -16,6 +31,33 @@ var A = (function () {
     return A;
 }());
 exports["default"] = A;
+var B = (function (_super) {
+    __extends(B, _super);
+    function B() {
+        return _super !== null && _super.apply(this, arguments) || this;
+    }
+    return B;
+}(A));
+new B().a.toExponential();
 //// [b.js]
 "use strict";
+var __extends = (this && this.__extends) || (function () {
+    var extendStatics = Object.setPrototypeOf ||
+        ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
+        function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
+    return function (d, b) {
+        extendStatics(d, b);
+        function __() { this.constructor = d; }
+        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
+    };
+})();
 exports.__esModule = true;
+var a_1 = require("./a");
+var C = (function (_super) {
+    __extends(C, _super);
+    function C() {
+        return _super !== null && _super.apply(this, arguments) || this;
+    }
+    return C;
+}(a_1["default"]));
+new C().a.toExponential();

tests/baselines/reference/exportDefaultAbstractClass.symbols

@@ -1,8 +1,31 @@
 === tests/cases/compiler/a.ts ===
-export default abstract class A {}
+export default abstract class A { a: number; }
+>A : Symbol(A, Decl(a.ts, 0, 0))
+>a : Symbol(A.a, Decl(a.ts, 0, 33))
+
+class B extends A {}
+>B : Symbol(B, Decl(a.ts, 0, 46))
 >A : Symbol(A, Decl(a.ts, 0, 0))
 
+new B().a.toExponential();
+>new B().a.toExponential : Symbol(Number.toExponential, Decl(lib.d.ts, --, --))
+>new B().a : Symbol(A.a, Decl(a.ts, 0, 33))
+>B : Symbol(B, Decl(a.ts, 0, 46))
+>a : Symbol(A.a, Decl(a.ts, 0, 33))
+>toExponential : Symbol(Number.toExponential, Decl(lib.d.ts, --, --))
+
 === tests/cases/compiler/b.ts ===
-import A from './a'
+import A from './a';
 >A : Symbol(A, Decl(b.ts, 0, 6))
 
+class C extends A {}
+>C : Symbol(C, Decl(b.ts, 0, 20))
+>A : Symbol(A, Decl(b.ts, 0, 6))
+
+new C().a.toExponential();
+>new C().a.toExponential : Symbol(Number.toExponential, Decl(lib.d.ts, --, --))
+>new C().a : Symbol(A.a, Decl(a.ts, 0, 33))
+>C : Symbol(C, Decl(b.ts, 0, 20))
+>a : Symbol(A.a, Decl(a.ts, 0, 33))
+>toExponential : Symbol(Number.toExponential, Decl(lib.d.ts, --, --))
+

tests/baselines/reference/exportDefaultAbstractClass.types

@@ -1,8 +1,35 @@
 === tests/cases/compiler/a.ts ===
-export default abstract class A {}
+export default abstract class A { a: number; }
+>A : A
+>a : number
+
+class B extends A {}
+>B : B
 >A : A
 
+new B().a.toExponential();
+>new B().a.toExponential() : string
+>new B().a.toExponential : (fractionDigits?: number) => string
+>new B().a : number
+>new B() : B
+>B : typeof B
+>a : number
+>toExponential : (fractionDigits?: number) => string
+
 === tests/cases/compiler/b.ts ===
-import A from './a'
+import A from './a';
 >A : typeof A
 
+class C extends A {}
+>C : C
+>A : A
+
+new C().a.toExponential();
+>new C().a.toExponential() : string
+>new C().a.toExponential : (fractionDigits?: number) => string
+>new C().a : number
+>new C() : C
+>C : typeof C
+>a : number
+>toExponential : (fractionDigits?: number) => string
+

tests/baselines/reference/exportDefaultInterface.js

@@ -0,0 +1,24 @@
+//// [tests/cases/compiler/exportDefaultInterface.ts] ////
+
+//// [a.ts]
+export default interface A { value: number; }
+
+var a: A;
+a.value.toExponential();
+
+//// [b.ts]
+import A from './a';
+
+var a: A;
+a.value.toExponential();
+
+//// [a.js]
+"use strict";
+exports.__esModule = true;
+var a;
+a.value.toExponential();
+//// [b.js]
+"use strict";
+exports.__esModule = true;
+var a;
+a.value.toExponential();

tests/baselines/reference/exportDefaultInterface.symbols

@@ -0,0 +1,31 @@
+=== tests/cases/compiler/a.ts ===
+export default interface A { value: number; }
+>A : Symbol(A, Decl(a.ts, 0, 0))
+>value : Symbol(A.value, Decl(a.ts, 0, 28))
+
+var a: A;
+>a : Symbol(a, Decl(a.ts, 2, 3))
+>A : Symbol(A, Decl(a.ts, 0, 0))
+
+a.value.toExponential();
+>a.value.toExponential : Symbol(Number.toExponential, Decl(lib.d.ts, --, --))
+>a.value : Symbol(A.value, Decl(a.ts, 0, 28))
+>a : Symbol(a, Decl(a.ts, 2, 3))
+>value : Symbol(A.value, Decl(a.ts, 0, 28))
+>toExponential : Symbol(Number.toExponential, Decl(lib.d.ts, --, --))
+
+=== tests/cases/compiler/b.ts ===
+import A from './a';
+>A : Symbol(A, Decl(b.ts, 0, 6))
+
+var a: A;
+>a : Symbol(a, Decl(b.ts, 2, 3))
+>A : Symbol(A, Decl(b.ts, 0, 6))
+
+a.value.toExponential();
+>a.value.toExponential : Symbol(Number.toExponential, Decl(lib.d.ts, --, --))
+>a.value : Symbol(A.value, Decl(a.ts, 0, 28))
+>a : Symbol(a, Decl(b.ts, 2, 3))
+>value : Symbol(A.value, Decl(a.ts, 0, 28))
+>toExponential : Symbol(Number.toExponential, Decl(lib.d.ts, --, --))
+

tests/baselines/reference/exportDefaultInterface.types

@@ -0,0 +1,33 @@
+=== tests/cases/compiler/a.ts ===
+export default interface A { value: number; }
+>A : A
+>value : number
+
+var a: A;
+>a : A
+>A : A
+
+a.value.toExponential();
+>a.value.toExponential() : string
+>a.value.toExponential : (fractionDigits?: number) => string
+>a.value : number
+>a : A
+>value : number
+>toExponential : (fractionDigits?: number) => string
+
+=== tests/cases/compiler/b.ts ===
+import A from './a';
+>A : any
+
+var a: A;
+>a : A
+>A : A
+
+a.value.toExponential();
+>a.value.toExponential() : string
+>a.value.toExponential : (fractionDigits?: number) => string
+>a.value : number
+>a : A
+>value : number
+>toExponential : (fractionDigits?: number) => string
+

tests/cases/compiler/exportDefaultAbstractClass.ts

@@ -1,5 +1,11 @@
-// @filename: a.ts
-export default abstract class A {}
-
-// @filename: b.ts
-import A from './a'
+// @Filename: a.ts
+export default abstract class A { a: number; }
+
+class B extends A {}
+new B().a.toExponential();
+
+// @Filename: b.ts
+import A from './a';
+
+class C extends A {}
+new C().a.toExponential();

tests/cases/compiler/exportDefaultInterface.ts

@@ -0,0 +1,11 @@
+// @Filename: a.ts
+export default interface A { value: number; }
+
+var a: A;
+a.value.toExponential();
+
+// @Filename: b.ts
+import A from './a';
+
+var a: A;
+a.value.toExponential();