[CSSolver] NFC: Add more test-cases for requirement checking in constrained extensions

Author: xedin

test/Constraints/rdar39931339.swift

@@ -4,16 +4,38 @@ protocol P {}
 
 struct S<T> {}
 
-class A : P {}
+class C : P {}
 
 extension S where T : P {
   typealias A = Int
   typealias B<U> = S<U>
 }
 
-_ = S<A>.A()           // Ok
+extension S where T == Float {
+  typealias C = Int
+}
+
+class A<T, U> {}
+
+extension A where T == [U], U: P {
+  typealias S1 = Int
+}
+
+extension A where T == [U], U == Int {
+  typealias S2 = Int
+}
+
+class B<U> : A<[U], U> {}
+
+_ = B<C>.S1()          // Ok
+_ = B<Int>.S2()        // Ok
+_ = B<Float>.S1()      // expected-error {{type 'Float' does not conform to protocol 'P'}}
+_ = B<String>.S2()     // expected-error {{'B<String>.S2.Type' (aka 'Int.Type') requires the types '[String]' and '[Int]' be equivalent}}
+
+_ = S<C>.A()           // Ok
 _ = S<Int>.A()         // expected-error {{type 'Int' does not conform to protocol 'P'}}
 _ = S<String>.B<Int>() // expected-error {{type 'String' does not conform to protocol 'P'}}
+_ = S<Int>.C()         // expected-error {{'S<Int>.C.Type' (aka 'Int.Type') requires the types 'Int' and 'Float' be equivalent}}
 
 func foo<T>(_ s: S<T>.Type) {
   _ = s.A() // expected-error {{type 'T' does not conform to protocol 'P'}}