From 4f38aa88c2eb917b92d0d4081f2752a3212e66f5 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sat, 27 Apr 2019 16:22:11 -0700
Subject: [PATCH] Add regression test

---
 .../substitutionTypesInIndexedAccessTypes.ts  | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 tests/cases/compiler/substitutionTypesInIndexedAccessTypes.ts

diff --git a/tests/cases/compiler/substitutionTypesInIndexedAccessTypes.ts b/tests/cases/compiler/substitutionTypesInIndexedAccessTypes.ts
new file mode 100644
index 0000000000000..4a89ea3759533
--- /dev/null
+++ b/tests/cases/compiler/substitutionTypesInIndexedAccessTypes.ts
@@ -0,0 +1,20 @@
+// @strict: true
+
+// Repro from #31086
+
+type UserArgs = {
+  select?: boolean
+};
+
+type Subset<T, U> = { [key in keyof T]: key extends keyof U ? T[key] : never };
+
+declare function withBoundary<T extends UserArgs>(args?: Subset<T, UserArgs>): T;
+declare function withoutBoundary<T extends UserArgs>(args?: T): T;
+
+const boundaryResult = withBoundary({
+  select: true,
+});
+
+const withoutBoundaryResult = withoutBoundary({
+  select: true,
+});