From 6262ac8b3d5c3b50b26b4c88be545621de4a574c Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Mon, 20 Aug 2018 12:41:48 -0700
Subject: [PATCH] Add tests

---
 tests/cases/compiler/infiniteConstraints.ts | 33 +++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 tests/cases/compiler/infiniteConstraints.ts

diff --git a/tests/cases/compiler/infiniteConstraints.ts b/tests/cases/compiler/infiniteConstraints.ts
new file mode 100644
index 0000000000..70d3879da6
--- /dev/null
+++ b/tests/cases/compiler/infiniteConstraints.ts
@@ -0,0 +1,33 @@
+// @strict: true
+
+// Both of the following types trigger the recursion limiter in getImmediateBaseConstraint
+
+type T1<B extends { [K in keyof B]: Extract<B[Exclude<keyof B, K>], { val: string }>["val"] }> = B;
+type T2<B extends { [K in keyof B]: B[Exclude<keyof B, K>]["val"] }> = B;
+
+// Repros from #22950
+
+type AProp<T extends { a: string }> = T
+
+declare function myBug<
+  T extends { [K in keyof T]: T[K] extends AProp<infer U> ? U : never }
+>(arg: T): T
+
+const out = myBug({obj1: {a: "test"}})
+
+type Value<V extends string = string> = Record<"val", V>;
+declare function value<V extends string>(val: V): Value<V>;
+
+declare function ensureNoDuplicates<
+  T extends {
+    [K in keyof T]: Extract<T[K], Value>["val"] extends Extract<T[Exclude<keyof T, K>], Value>["val"]
+      ? never
+      : any
+  }
+>(vals: T): void;
+
+const noError = ensureNoDuplicates({main: value("test"), alternate: value("test2")});
+
+const shouldBeNoError = ensureNoDuplicates({main: value("test")});
+
+const shouldBeError = ensureNoDuplicates({main: value("dup"), alternate: value("dup")});