From 855488fc6d5b9311b463da64f1d32d00ea58cce2 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Fri, 6 Jan 2017 17:35:09 -0800
Subject: [PATCH] Add additional regression test

---
 .../circularIndexedAccessErrors.errors.txt    | 20 +++++++++++++++++--
 .../reference/circularIndexedAccessErrors.js  | 18 ++++++++++++++++-
 .../keyof/circularIndexedAccessErrors.ts      | 11 +++++++++-
 3 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/tests/baselines/reference/circularIndexedAccessErrors.errors.txt b/tests/baselines/reference/circularIndexedAccessErrors.errors.txt
index e5eaa08d05..f76cfca073 100644
--- a/tests/baselines/reference/circularIndexedAccessErrors.errors.txt
+++ b/tests/baselines/reference/circularIndexedAccessErrors.errors.txt
@@ -2,9 +2,11 @@ tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts(3,5): error T
 tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts(7,5): error TS2502: 'x' is referenced directly or indirectly in its own type annotation.
 tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts(19,5): error TS2502: 'x' is referenced directly or indirectly in its own type annotation.
 tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts(23,5): error TS2502: 'x' is referenced directly or indirectly in its own type annotation.
+tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts(38,24): error TS2313: Type parameter 'T' has a circular constraint.
+tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts(38,30): error TS2536: Type '"hello"' cannot be used to index type 'T'.
 
 
-==== tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts (4 errors) ====
+==== tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts (6 errors) ====
     
     type T1 = {
         x: T1["x"];  // Error
@@ -42,4 +44,18 @@ tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts(23,5): error
         x: this["y"];
         y: this["z"];
         z: this["x"];
-    }
\ No newline at end of file
+    }
+    
+    // Repro from #12627
+    
+    interface Foo {
+        hello: boolean;
+    }
+    
+    function foo<T extends Foo | T["hello"]>() {
+                           ~~~~~~~~~~~~~~~~
+!!! error TS2313: Type parameter 'T' has a circular constraint.
+                                 ~~~~~~~~~~
+!!! error TS2536: Type '"hello"' cannot be used to index type 'T'.
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/circularIndexedAccessErrors.js b/tests/baselines/reference/circularIndexedAccessErrors.js
index 2e4ae3bd84..97d059bce1 100644
--- a/tests/baselines/reference/circularIndexedAccessErrors.js
+++ b/tests/baselines/reference/circularIndexedAccessErrors.js
@@ -28,7 +28,17 @@ class C2 {
     x: this["y"];
     y: this["z"];
     z: this["x"];
-}
+}
+
+// Repro from #12627
+
+interface Foo {
+    hello: boolean;
+}
+
+function foo<T extends Foo | T["hello"]>() {
+}
+
 
 //// [circularIndexedAccessErrors.js]
 var x2x = x2.x;
@@ -42,6 +52,8 @@ var C2 = (function () {
     }
     return C2;
 }());
+function foo() {
+}
 
 
 //// [circularIndexedAccessErrors.d.ts]
@@ -68,3 +80,7 @@ declare class C2 {
     y: this["z"];
     z: this["x"];
 }
+interface Foo {
+    hello: boolean;
+}
+declare function foo<T extends Foo | T["hello"]>(): void;
diff --git a/tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts b/tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts
index 2243ee8aaa..a53fc6fbf7 100644
--- a/tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts
+++ b/tests/cases/conformance/types/keyof/circularIndexedAccessErrors.ts
@@ -28,4 +28,13 @@ class C2 {
     x: this["y"];
     y: this["z"];
     z: this["x"];
-}
\ No newline at end of file
+}
+
+// Repro from #12627
+
+interface Foo {
+    hello: boolean;
+}
+
+function foo<T extends Foo | T["hello"]>() {
+}