Merge pull request #28116 from hborla/same-type-regression

[ConstraintSystem] Allow binding metatypes to succeed if one contains a hole

Author: hborla

lib/Sema/CSSimplify.cpp

@@ -3399,6 +3399,13 @@ bool ConstraintSystem::repairFailures(
     break;
   }
 
+  case ConstraintLocator::InstanceType: {
+    if (lhs->hasUnresolvedType() || rhs->hasUnresolvedType())
+      return true;
+
+    break;
+  }
+
   default:
     break;
   }

test/Constraints/same_types.swift

@@ -320,3 +320,16 @@ struct Bar<A: P1, B: P1> where A.Assoc == B.Assoc {
     fatalError()
   }
 }
+
+protocol P7 {
+  associatedtype A
+  static func fn(args: A)
+}
+
+class R<T>: P7 where T: P7, T.A == T.Type { // expected-note {{'T' declared as parameter to type 'R'}}
+  typealias A = T.Type
+  static func fn(args: T.Type) {}
+}
+
+R.fn(args: R.self) // expected-error {{generic parameter 'T' could not be inferred}}
+// expected-note@-1 {{explicitly specify the generic arguments to fix this issue}}

validation-test/Sema/type_checker_perf/fast/rdar21374729.swift

@@ -7,9 +7,11 @@ protocol P {
 }
 
 class R<T> : P where T : P, T.A == T.Type {
+  // expected-note@-1 {{'T' declared as parameter to type 'R'}}
   typealias A = T.Type
   static func fn(args: T.Type) {}
 }
 
 R.fn(args: R.self)
-// expected-error@-1 {{type of expression is ambiguous without more context}}
+// expected-error@-1 {{generic parameter 'T' could not be inferred}}
+// expected-note@-2 {{explicitly specify the generic arguments to fix this issue}}