Merge remote-tracking branch 'origin/master' into master-rebranch

Author: swift-ci

lib/Sema/TypeCheckProtocol.cpp

@@ -850,7 +850,14 @@ swift::matchWitness(WitnessChecker::RequirementEnvironmentCache &reqEnvCache,
   Type openedFullWitnessType;
   Type reqType, openedFullReqType;
 
-  auto reqSig = req->getInnermostDeclContext()->getGenericSignatureOfContext();
+  GenericSignature reqSig = proto->getGenericSignature();
+  if (auto *funcDecl = dyn_cast<AbstractFunctionDecl>(req)) {
+    if (funcDecl->isGeneric())
+      reqSig = funcDecl->getGenericSignature();
+  } else if (auto *subscriptDecl = dyn_cast<SubscriptDecl>(req)) {
+    if (subscriptDecl->isGeneric())
+      reqSig = subscriptDecl->getGenericSignature();
+  }
 
   ClassDecl *covariantSelf = nullptr;
   if (witness->getDeclContext()->getExtendedProtocolDecl()) {

test/decl/protocol/req/unsatisfiable.swift

@@ -58,3 +58,25 @@ protocol P4 {
 protocol P5 {
   associatedtype Y where Y : S // expected-error {{type 'Self.Y' constrained to non-protocol, non-class type 'S'}}
 }
+
+protocol P6 {
+  associatedtype T
+  associatedtype U
+
+  func foo() where T == U
+  // expected-error@-1 {{instance method requirement 'foo()' cannot add constraint 'Self.T == Self.U' on 'Self'}}
+  // expected-note@-2 {{protocol requires function 'foo()' with type '() -> ()'; do you want to add a stub?}}
+}
+
+struct S2 : P6 {
+  // expected-error@-1 {{type 'S2' does not conform to protocol 'P6'}}
+  typealias T = Int
+  typealias U = String
+
+  func foo() {}
+  // expected-note@-1 {{candidate has non-matching type '() -> ()'}}
+
+  // FIXME: This error is bogus and should be omitted on account of the protocol requirement itself
+  // being invalid.
+}
+

validation-test/compiler_crashers_2_fixed/rdar62268062.swift

@@ -0,0 +1,41 @@
+// RUN: %target-swift-frontend -emit-ir %s
+
+public protocol HorseSaddle {}
+public enum EnglishSaddle : HorseSaddle {}
+
+public enum WesternSaddle<A, B> : HorseSaddle {}
+
+public protocol Horse {
+    associatedtype Body : Horse
+
+    associatedtype Saddle: HorseSaddle
+
+    var body: Body { get }
+}
+
+extension Horse {
+    typealias Saddle = Body.Saddle
+}
+
+public struct DraftHorse<T> : Pony {
+    public typealias Saddle = EnglishSaddle
+    public typealias Body = Never
+    var contents: T
+}
+
+// MARK: - Implementation detail
+
+extension Never : Horse {
+    public typealias Saddle = EnglishSaddle
+    public typealias Body = Never
+
+    public var body: Never {
+        switch self {}
+    }
+}
+
+protocol Pony : Horse where Body == Never {}
+extension Pony {
+    public var body: Never { fatalError() }
+}
+