Add regression test

Author: ahejlsberg

tests/baselines/reference/limitDeepInstantiations.errors.txt

@@ -0,0 +1,15 @@
+tests/cases/compiler/limitDeepInstantiations.ts(3,35): error TS2550: Generic type instantiation is excessively deep and possibly infinite.
+tests/cases/compiler/limitDeepInstantiations.ts(5,13): error TS2344: Type '"false"' does not satisfy the constraint '"true"'.
+
+
+==== tests/cases/compiler/limitDeepInstantiations.ts (2 errors) ====
+    // Repro from #14837
+    
+    type Foo<T extends "true", B> = { "true": Foo<T, Foo<T, B>> }[T];
+                                      ~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2550: Generic type instantiation is excessively deep and possibly infinite.
+    let f1: Foo<"true", {}>;
+    let f2: Foo<"false", {}>;
+                ~~~~~~~
+!!! error TS2344: Type '"false"' does not satisfy the constraint '"true"'.
+    

tests/baselines/reference/limitDeepInstantiations.js

@@ -0,0 +1,12 @@
+//// [limitDeepInstantiations.ts]
+// Repro from #14837
+
+type Foo<T extends "true", B> = { "true": Foo<T, Foo<T, B>> }[T];
+let f1: Foo<"true", {}>;
+let f2: Foo<"false", {}>;
+
+
+//// [limitDeepInstantiations.js]
+// Repro from #14837
+var f1;
+var f2;

tests/cases/compiler/limitDeepInstantiations.ts

@@ -0,0 +1,5 @@
+// Repro from #14837
+
+type Foo<T extends "true", B> = { "true": Foo<T, Foo<T, B>> }[T];
+let f1: Foo<"true", {}>;
+let f2: Foo<"false", {}>;