Ensure export= symbol from JavaScript always has a valueDeclaration

src/compiler/binder.ts

@@ -2691,7 +2691,8 @@ namespace ts {
             const flags = exportAssignmentIsAlias(node)
                 ? SymbolFlags.Alias // An export= with an EntityNameExpression or a ClassExpression exports all meanings of that identifier or class
                 : SymbolFlags.Property | SymbolFlags.ExportValue | SymbolFlags.ValueModule;
-            declareSymbol(file.symbol.exports!, file.symbol, node, flags | SymbolFlags.Assignment, SymbolFlags.None);
+            const symbol = declareSymbol(file.symbol.exports!, file.symbol, node, flags | SymbolFlags.Assignment, SymbolFlags.None);
+            setValueDeclaration(symbol, node);
         }
 
         function bindThisPropertyAssignment(node: BindablePropertyAssignmentExpression | PropertyAccessExpression | LiteralLikeElementAccessExpression) {

tests/baselines/reference/javascriptImportDefaultBadExport.errors.txt

@@ -0,0 +1,16 @@
+/b.js(1,8): error TS1259: Module '"/a"' can only be default-imported using the 'esModuleInterop' flag
+
+
+==== /a.js (0 errors) ====
+    // https://github.com/microsoft/TypeScript/issues/34481
+
+
+    const alias = {};
+    module.exports = alias;
+
+==== /b.js (1 errors) ====
+    import a from "./a";
+           ~
+!!! error TS1259: Module '"/a"' can only be default-imported using the 'esModuleInterop' flag
+!!! related TS2594 /a.js:5:1: This module is declared with using 'export =', and can only be used with a default import when using the 'esModuleInterop' flag.
+

tests/baselines/reference/javascriptImportDefaultBadExport.symbols

@@ -0,0 +1,17 @@
+=== /a.js ===
+// https://github.com/microsoft/TypeScript/issues/34481
+
+
+const alias = {};
+>alias : Symbol(alias, Decl(a.js, 3, 5))
+
+module.exports = alias;
+>module.exports : Symbol("/a", Decl(a.js, 0, 0))
+>module : Symbol(export=, Decl(a.js, 3, 17))
+>exports : Symbol(export=, Decl(a.js, 3, 17))
+>alias : Symbol(alias, Decl(a.js, 3, 5))
+
+=== /b.js ===
+import a from "./a";
+>a : Symbol(a, Decl(b.js, 0, 6))
+

tests/baselines/reference/javascriptImportDefaultBadExport.types

@@ -0,0 +1,19 @@
+=== /a.js ===
+// https://github.com/microsoft/TypeScript/issues/34481
+
+
+const alias = {};
+>alias : {}
+>{} : {}
+
+module.exports = alias;
+>module.exports = alias : {}
+>module.exports : {}
+>module : { "/a": {}; }
+>exports : {}
+>alias : {}
+
+=== /b.js ===
+import a from "./a";
+>a : any
+

tests/cases/compiler/javascriptImportDefaultBadExport.ts

@@ -0,0 +1,12 @@
+// https://github.com/microsoft/TypeScript/issues/34481
+
+// @allowJs: true
+// @checkJs: true
+// @noEmit: true
+
+// @Filename: /a.js
+const alias = {};
+module.exports = alias;
+
+// @Filename: /b.js
+import a from "./a";