From a320e1b554af999fb3452e784d1838c5d57272dc Mon Sep 17 00:00:00 2001
From: Eli Barzilay <eli@barzilay.org>
Date: Wed, 29 Jul 2020 11:41:58 -0400
Subject: [PATCH] Make `getLocalSymbolForExportDefault` look harder for an
 export

Look for a symbol that has a `.localSymbol` property instead of blindly
using the first one.

Fixes #37829.
---
 src/compiler/utilities.ts                             |  6 +++++-
 .../reference/exportDefaultInterfaceAndValue.js       | 11 +++++++++++
 .../reference/exportDefaultInterfaceAndValue.symbols  | 10 ++++++++++
 .../reference/exportDefaultInterfaceAndValue.types    | 10 ++++++++++
 .../cases/compiler/exportDefaultInterfaceAndValue.ts  |  3 +++
 5 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/exportDefaultInterfaceAndValue.js
 create mode 100644 tests/baselines/reference/exportDefaultInterfaceAndValue.symbols
 create mode 100644 tests/baselines/reference/exportDefaultInterfaceAndValue.types
 create mode 100644 tests/cases/compiler/exportDefaultInterfaceAndValue.ts

diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 41d513a2523..b978c3dbc4e 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -4769,7 +4769,11 @@ namespace ts {
     }
 
     export function getLocalSymbolForExportDefault(symbol: Symbol) {
-        return isExportDefaultSymbol(symbol) ? symbol.declarations[0].localSymbol : undefined;
+        if (!isExportDefaultSymbol(symbol)) return undefined;
+        for (const decl of symbol.declarations) {
+            if (decl.localSymbol) return decl.localSymbol;
+        }
+        return undefined;
     }
 
     function isExportDefaultSymbol(symbol: Symbol): boolean {
diff --git a/tests/baselines/reference/exportDefaultInterfaceAndValue.js b/tests/baselines/reference/exportDefaultInterfaceAndValue.js
new file mode 100644
index 00000000000..f98e4a04e76
--- /dev/null
+++ b/tests/baselines/reference/exportDefaultInterfaceAndValue.js
@@ -0,0 +1,11 @@
+//// [exportDefaultInterfaceAndValue.ts]
+export default interface A { a: string; }
+export default function() { return 1; }
+declare var x: A;
+
+
+//// [exportDefaultInterfaceAndValue.js]
+"use strict";
+exports.__esModule = true;
+function default_1() { return 1; }
+exports["default"] = default_1;
diff --git a/tests/baselines/reference/exportDefaultInterfaceAndValue.symbols b/tests/baselines/reference/exportDefaultInterfaceAndValue.symbols
new file mode 100644
index 00000000000..9ab2e49b943
--- /dev/null
+++ b/tests/baselines/reference/exportDefaultInterfaceAndValue.symbols
@@ -0,0 +1,10 @@
+=== tests/cases/compiler/exportDefaultInterfaceAndValue.ts ===
+export default interface A { a: string; }
+>A : Symbol(A, Decl(exportDefaultInterfaceAndValue.ts, 0, 41), Decl(exportDefaultInterfaceAndValue.ts, 0, 0))
+>a : Symbol(A.a, Decl(exportDefaultInterfaceAndValue.ts, 0, 28))
+
+export default function() { return 1; }
+declare var x: A;
+>x : Symbol(x, Decl(exportDefaultInterfaceAndValue.ts, 2, 11))
+>A : Symbol(A, Decl(exportDefaultInterfaceAndValue.ts, 0, 41), Decl(exportDefaultInterfaceAndValue.ts, 0, 0))
+
diff --git a/tests/baselines/reference/exportDefaultInterfaceAndValue.types b/tests/baselines/reference/exportDefaultInterfaceAndValue.types
new file mode 100644
index 00000000000..7b3e0cbbd15
--- /dev/null
+++ b/tests/baselines/reference/exportDefaultInterfaceAndValue.types
@@ -0,0 +1,10 @@
+=== tests/cases/compiler/exportDefaultInterfaceAndValue.ts ===
+export default interface A { a: string; }
+>a : string
+
+export default function() { return 1; }
+>1 : 1
+
+declare var x: A;
+>x : A
+
diff --git a/tests/cases/compiler/exportDefaultInterfaceAndValue.ts b/tests/cases/compiler/exportDefaultInterfaceAndValue.ts
new file mode 100644
index 00000000000..411e5f2706c
--- /dev/null
+++ b/tests/cases/compiler/exportDefaultInterfaceAndValue.ts
@@ -0,0 +1,3 @@
+export default interface A { a: string; }
+export default function() { return 1; }
+declare var x: A;