From 5524a61ce9d59b5874fe8a32f851763723eb9c74 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Thu, 12 Dec 2019 16:03:21 -0800
Subject: [PATCH] Add regression test

---
 .../compiler/unionReductionMutualSubtypes.ts      | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 tests/cases/compiler/unionReductionMutualSubtypes.ts

diff --git a/tests/cases/compiler/unionReductionMutualSubtypes.ts b/tests/cases/compiler/unionReductionMutualSubtypes.ts
new file mode 100644
index 00000000000..aa1c1320a0d
--- /dev/null
+++ b/tests/cases/compiler/unionReductionMutualSubtypes.ts
@@ -0,0 +1,15 @@
+// @strict: true
+
+// Repro from #35414
+
+interface ReturnVal {
+    something(): void;
+}
+
+const k: ReturnVal = { something() { } }
+
+declare const val: ReturnVal;
+function run(options: { something?(b?: string): void }) {
+    const something = options.something ?? val.something;
+    something('');
+}