From bf49e8a56d54ffe293d9d12bd772a366f34dc26a Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Thu, 17 Oct 2019 17:16:50 -0700
Subject: [PATCH] Ensure export= symbol from JavaScript always has a
 valueDeclaration

---
 src/compiler/binder.ts                        |  3 ++-
 ...avascriptImportDefaultBadExport.errors.txt | 16 ++++++++++++++++
 .../javascriptImportDefaultBadExport.symbols  | 17 +++++++++++++++++
 .../javascriptImportDefaultBadExport.types    | 19 +++++++++++++++++++
 .../javascriptImportDefaultBadExport.ts       | 12 ++++++++++++
 5 files changed, 66 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/javascriptImportDefaultBadExport.errors.txt
 create mode 100644 tests/baselines/reference/javascriptImportDefaultBadExport.symbols
 create mode 100644 tests/baselines/reference/javascriptImportDefaultBadExport.types
 create mode 100644 tests/cases/compiler/javascriptImportDefaultBadExport.ts

diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index e3fcc4624cf57..fff191ac82160 100644
--- a/src/compiler/binder.ts
+++ b/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) {
diff --git a/tests/baselines/reference/javascriptImportDefaultBadExport.errors.txt b/tests/baselines/reference/javascriptImportDefaultBadExport.errors.txt
new file mode 100644
index 0000000000000..71ff85e2155fe
--- /dev/null
+++ b/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.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/javascriptImportDefaultBadExport.symbols b/tests/baselines/reference/javascriptImportDefaultBadExport.symbols
new file mode 100644
index 0000000000000..b5506996aff79
--- /dev/null
+++ b/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))
+
diff --git a/tests/baselines/reference/javascriptImportDefaultBadExport.types b/tests/baselines/reference/javascriptImportDefaultBadExport.types
new file mode 100644
index 0000000000000..81d68cbdf964c
--- /dev/null
+++ b/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
+
diff --git a/tests/cases/compiler/javascriptImportDefaultBadExport.ts b/tests/cases/compiler/javascriptImportDefaultBadExport.ts
new file mode 100644
index 0000000000000..c1f2455e11d69
--- /dev/null
+++ b/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";