fix(45233): allow type assertion in ExportAssignment with JSDoc type definition (#45342)

Author: a-tarasyuk

src/compiler/checker.ts

@@ -9094,7 +9094,7 @@ namespace ts {
             }
             let type: Type;
             if (declaration.kind === SyntaxKind.ExportAssignment) {
-                type = widenTypeForVariableLikeDeclaration(checkExpressionCached((declaration as ExportAssignment).expression), declaration);
+                type = widenTypeForVariableLikeDeclaration(tryGetTypeFromEffectiveTypeNode(declaration) || checkExpressionCached((declaration as ExportAssignment).expression), declaration);
             }
             else if (
                 isBinaryExpression(declaration) ||
@@ -9350,13 +9350,15 @@ namespace ts {
             if (!links.type) {
                 const targetSymbol = resolveAlias(symbol);
                 const exportSymbol = symbol.declarations && getTargetOfAliasDeclaration(getDeclarationOfAliasSymbol(symbol)!, /*dontResolveAlias*/ true);
+                const declaredType = firstDefined(exportSymbol?.declarations, d => isExportAssignment(d) ? tryGetTypeFromEffectiveTypeNode(d) : undefined);
                 // It only makes sense to get the type of a value symbol. If the result of resolving
                 // the alias is not a value, then it has no type. To get the type associated with a
                 // type symbol, call getDeclaredTypeOfSymbol.
                 // This check is important because without it, a call to getTypeOfSymbol could end
                 // up recursively calling getTypeOfAlias, causing a stack overflow.
                 links.type = exportSymbol?.declarations && isDuplicatedCommonJSExport(exportSymbol.declarations) && symbol.declarations!.length ? getFlowTypeFromCommonJSExport(exportSymbol)
                     : isDuplicatedCommonJSExport(symbol.declarations) ? autoType
+                    : declaredType ? declaredType
                     : targetSymbol.flags & SymbolFlags.Value ? getTypeOfSymbol(targetSymbol)
                     : errorType;
             }
@@ -38863,11 +38865,16 @@ namespace ts {
             if (!checkGrammarDecoratorsAndModifiers(node) && hasEffectiveModifiers(node)) {
                 grammarErrorOnFirstToken(node, Diagnostics.An_export_assignment_cannot_have_modifiers);
             }
+
+            const typeAnnotationNode = getEffectiveTypeAnnotationNode(node);
+            if (typeAnnotationNode) {
+                checkTypeAssignableTo(checkExpressionCached(node.expression), getTypeFromTypeNode(typeAnnotationNode), node.expression);
+            }
+
             if (node.expression.kind === SyntaxKind.Identifier) {
                 const id = node.expression as Identifier;
                 const sym = resolveEntityName(id, SymbolFlags.All, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, node);
                 if (sym) {
-
                     markAliasReferenced(sym, id);
                     // If not a value, we're interpreting the identifier as a type export, along the lines of (`export { Id as default }`)
                     const target = sym.flags & SymbolFlags.Alias ? resolveAlias(sym) : sym;

tests/baselines/reference/checkJsdocTypeTagOnExportAssignment1.errors.txt

@@ -0,0 +1,23 @@
+tests/cases/compiler/a.js(8,18): error TS2322: Type '{ c: boolean; }' is not assignable to type 'Foo'.
+  Object literal may only specify known properties, and 'c' does not exist in type 'Foo'.
+
+
+==== tests/cases/compiler/checkJsdocTypeTagOnExportAssignment1.js (0 errors) ====
+    
+==== tests/cases/compiler/a.js (1 errors) ====
+    /**
+     * @typedef {Object} Foo
+     * @property {boolean} a
+     * @property {boolean} b
+     */
+    
+    /** @type {Foo} */
+    export default { c: false };
+                     ~~~~~~~~
+!!! error TS2322: Type '{ c: boolean; }' is not assignable to type 'Foo'.
+!!! error TS2322:   Object literal may only specify known properties, and 'c' does not exist in type 'Foo'.
+    
+==== tests/cases/compiler/b.js (0 errors) ====
+    import a from "./a";
+    a;
+    

tests/baselines/reference/checkJsdocTypeTagOnExportAssignment1.js

@@ -0,0 +1,35 @@
+//// [tests/cases/compiler/checkJsdocTypeTagOnExportAssignment1.ts] ////
+
+//// [checkJsdocTypeTagOnExportAssignment1.js]
+
+//// [a.js]
+/**
+ * @typedef {Object} Foo
+ * @property {boolean} a
+ * @property {boolean} b
+ */
+
+/** @type {Foo} */
+export default { c: false };
+
+//// [b.js]
+import a from "./a";
+a;
+
+
+//// [checkJsdocTypeTagOnExportAssignment1.js]
+//// [a.js]
+"use strict";
+/**
+ * @typedef {Object} Foo
+ * @property {boolean} a
+ * @property {boolean} b
+ */
+exports.__esModule = true;
+/** @type {Foo} */
+exports["default"] = { c: false };
+//// [b.js]
+"use strict";
+exports.__esModule = true;
+var a_1 = require("./a");
+a_1["default"];

tests/baselines/reference/checkJsdocTypeTagOnExportAssignment1.symbols

@@ -0,0 +1,20 @@
+=== tests/cases/compiler/checkJsdocTypeTagOnExportAssignment1.js ===
+
+No type information for this code.=== tests/cases/compiler/a.js ===
+/**
+ * @typedef {Object} Foo
+ * @property {boolean} a
+ * @property {boolean} b
+ */
+
+/** @type {Foo} */
+export default { c: false };
+>c : Symbol(c, Decl(a.js, 7, 16))
+
+=== tests/cases/compiler/b.js ===
+import a from "./a";
+>a : Symbol(a, Decl(b.js, 0, 6))
+
+a;
+>a : Symbol(a, Decl(b.js, 0, 6))
+

tests/baselines/reference/checkJsdocTypeTagOnExportAssignment1.types

@@ -0,0 +1,22 @@
+=== tests/cases/compiler/checkJsdocTypeTagOnExportAssignment1.js ===
+
+No type information for this code.=== tests/cases/compiler/a.js ===
+/**
+ * @typedef {Object} Foo
+ * @property {boolean} a
+ * @property {boolean} b
+ */
+
+/** @type {Foo} */
+export default { c: false };
+>{ c: false } : { c: boolean; }
+>c : boolean
+>false : false
+
+=== tests/cases/compiler/b.js ===
+import a from "./a";
+>a : import("tests/cases/compiler/a").Foo
+
+a;
+>a : import("tests/cases/compiler/a").Foo
+

tests/baselines/reference/checkJsdocTypeTagOnExportAssignment2.errors.txt

@@ -0,0 +1,23 @@
+tests/cases/compiler/b.js(2,18): error TS2322: Type '{ c: boolean; }' is not assignable to type 'Foo'.
+  Object literal may only specify known properties, and 'c' does not exist in type 'Foo'.
+
+
+==== tests/cases/compiler/checkJsdocTypeTagOnExportAssignment2.js (0 errors) ====
+    
+==== tests/cases/compiler/a.ts (0 errors) ====
+    export interface Foo {
+        a: number;
+        b: number;
+    }
+    
+==== tests/cases/compiler/b.js (1 errors) ====
+    /** @type {import("./a").Foo} */
+    export default { c: false };
+                     ~~~~~~~~
+!!! error TS2322: Type '{ c: boolean; }' is not assignable to type 'Foo'.
+!!! error TS2322:   Object literal may only specify known properties, and 'c' does not exist in type 'Foo'.
+    
+==== tests/cases/compiler/c.js (0 errors) ====
+    import b from "./b";
+    b;
+    

tests/baselines/reference/checkJsdocTypeTagOnExportAssignment2.js

@@ -0,0 +1,33 @@
+//// [tests/cases/compiler/checkJsdocTypeTagOnExportAssignment2.ts] ////
+
+//// [checkJsdocTypeTagOnExportAssignment2.js]
+
+//// [a.ts]
+export interface Foo {
+    a: number;
+    b: number;
+}
+
+//// [b.js]
+/** @type {import("./a").Foo} */
+export default { c: false };
+
+//// [c.js]
+import b from "./b";
+b;
+
+
+//// [checkJsdocTypeTagOnExportAssignment2.js]
+//// [a.js]
+"use strict";
+exports.__esModule = true;
+//// [b.js]
+"use strict";
+exports.__esModule = true;
+/** @type {import("./a").Foo} */
+exports["default"] = { c: false };
+//// [c.js]
+"use strict";
+exports.__esModule = true;
+var b_1 = require("./b");
+b_1["default"];

tests/baselines/reference/checkJsdocTypeTagOnExportAssignment2.symbols

@@ -0,0 +1,25 @@
+=== tests/cases/compiler/checkJsdocTypeTagOnExportAssignment2.js ===
+
+No type information for this code.=== tests/cases/compiler/a.ts ===
+export interface Foo {
+>Foo : Symbol(Foo, Decl(a.ts, 0, 0))
+
+    a: number;
+>a : Symbol(Foo.a, Decl(a.ts, 0, 22))
+
+    b: number;
+>b : Symbol(Foo.b, Decl(a.ts, 1, 14))
+}
+
+=== tests/cases/compiler/b.js ===
+/** @type {import("./a").Foo} */
+export default { c: false };
+>c : Symbol(c, Decl(b.js, 1, 16))
+
+=== tests/cases/compiler/c.js ===
+import b from "./b";
+>b : Symbol(b, Decl(c.js, 0, 6))
+
+b;
+>b : Symbol(b, Decl(c.js, 0, 6))
+

tests/baselines/reference/checkJsdocTypeTagOnExportAssignment2.types

@@ -0,0 +1,25 @@
+=== tests/cases/compiler/checkJsdocTypeTagOnExportAssignment2.js ===
+
+No type information for this code.=== tests/cases/compiler/a.ts ===
+export interface Foo {
+    a: number;
+>a : number
+
+    b: number;
+>b : number
+}
+
+=== tests/cases/compiler/b.js ===
+/** @type {import("./a").Foo} */
+export default { c: false };
+>{ c: false } : { c: boolean; }
+>c : boolean
+>false : false
+
+=== tests/cases/compiler/c.js ===
+import b from "./b";
+>b : import("tests/cases/compiler/a").Foo
+
+b;
+>b : import("tests/cases/compiler/a").Foo
+

tests/baselines/reference/checkJsdocTypeTagOnExportAssignment3.errors.txt

@@ -0,0 +1,23 @@
+tests/cases/compiler/a.js(10,16): error TS2739: Type '{ c: number; }' is missing the following properties from type 'Foo': a, b
+
+
+==== tests/cases/compiler/checkJsdocTypeTagOnExportAssignment3.js (0 errors) ====
+    
+==== tests/cases/compiler/a.js (1 errors) ====
+    /**
+     * @typedef {Object} Foo
+     * @property {boolean} a
+     * @property {boolean} b
+     */
+    
+    const bar = { c: 1 };
+    
+    /** @type {Foo} */
+    export default bar;
+                   ~~~
+!!! error TS2739: Type '{ c: number; }' is missing the following properties from type 'Foo': a, b
+    
+==== tests/cases/compiler/b.js (0 errors) ====
+    import a from "./a";
+    a;
+