Merge pull request swiftlang#19760 from gregomni/8902

[Sema]Allow associated type inference for requirement returning dynamic Self...

Author: slavapestov

lib/Sema/TypeCheckProtocol.cpp

@@ -545,6 +545,14 @@ swift::matchWitness(
     // Result types must match.
     // FIXME: Could allow (trivial?) subtyping here.
     if (!ignoreReturnType) {
+      if (reqResultType->hasDynamicSelfType()) {
+        auto classDecl = witness->getDeclContext()->getSelfClassDecl();
+        if (!classDecl || classDecl->isFinal() ||
+            witnessResultType->hasDynamicSelfType())
+          reqResultType = reqResultType->eraseDynamicSelfType();
+        witnessResultType = witnessResultType->eraseDynamicSelfType();
+      }
+
       auto reqTypeIsIUO =
           req->getAttrs().hasAttribute<ImplicitlyUnwrappedOptionalAttr>();
       auto witnessTypeIsIUO =

test/decl/protocol/conforms/self.swift

@@ -86,3 +86,29 @@ extension Node {
 }
 
 class IntNode: Node {}
+
+// SR-8902
+protocol P8902 {
+    associatedtype A // expected-note {{protocol requires nested type 'A'; do you want to add it?}}
+    func f(_ x: A) -> Self
+}
+struct S : P8902 {
+    func f(_ x: Bool) -> S { fatalError() }
+}
+class C8902 : P8902 { // expected-error {{type 'C8902' does not conform to protocol 'P8902'}}
+    func f(_ x: Bool) -> C8902 { fatalError() }
+}
+final class C8902b : P8902 {
+    func f(_ x: Bool) -> C8902b { fatalError() }
+}
+class C8902c : P8902 {
+    func f(_ x: Bool) -> Self { fatalError() }
+}
+protocol P8902complex {
+  associatedtype A
+  func f() -> (A, Self?)
+}
+final class C8902complex : P8902complex {
+  func f() -> (Bool, C8902complex?) { fatalError() }
+}
+

validation-test/compiler_crashers_2_fixed/0155-sr7364.swift

@@ -1,4 +1,4 @@
-// RUN: not %target-swift-frontend %s -emit-ir
+// RUN: %target-swift-frontend %s -emit-ir
 
 
 public protocol E {