Merge pull request swiftlang#16676 from xedin/rdar-40165062

[TypeChecker] Add test-case for rdar://problem/40165062

Author: xedin

validation-test/compiler_crashers_2_fixed/0158-rdar40165062.swift

@@ -0,0 +1,14 @@
+// RUN: %target-typecheck-verify-swift
+
+struct Foo<T, U> {
+  var value: U
+  func bar() -> Foo<T, U> {
+    return Foo(value) // expected-error {{generic parameter 'T' could not be inferred}}
+  }
+}
+
+extension Foo where T == U {
+  init(_ value: U)  {
+    self.value = value
+  }
+}