Merge pull request #59370 from slavapestov/rqm-unavailable-conformance-fix-5.7

RequirementMachine: Fix handling of unavailable Sendable conformances in concretizeNestedTypesFromConcreteParent() [5.7]

Author: slavapestov

lib/AST/RequirementMachine/ConcreteTypeWitness.cpp

@@ -153,10 +153,13 @@ void PropertyMap::concretizeNestedTypesFromConcreteParent(
     // subclasses of 'C' which are 'Sendable'.
     bool allowMissing = (requirementKind == RequirementKind::SameType);
 
+    bool allowUnavailable =
+        !proto->isSpecificProtocol(KnownProtocolKind::Sendable);
     auto conformance = module->lookupConformance(concreteType,
                                                  const_cast<ProtocolDecl *>(proto),
-                                                 allowMissing);
-    if (conformance.isInvalid() || conformance.hasUnavailableConformance()) {
+                                                 allowMissing,
+                                                 allowUnavailable);
+    if (conformance.isInvalid()) {
       // For superclass rules, it is totally fine to have a signature like:
       //
       // protocol P {}

test/Generics/unavailable_conformances.swift

@@ -0,0 +1,35 @@
+// RUN: %target-typecheck-verify-swift
+
+protocol P { }
+
+struct X { }
+
+@available(*, unavailable)
+extension X: P { }
+
+struct Y<T: P> { }
+
+@available(*, unavailable)
+extension Y {
+  // Okay, because the unavailable conformance is used within an
+  // unavailable context.
+  init() where T == X { }
+}
+
+// A more elaborate setup that hits the conformance check in property map
+// construction rather than concrete contraction.
+
+protocol AssocP {}
+
+@available(*, unavailable)
+struct ConcreteP {}
+
+@available(*, unavailable)
+extension ConcreteP: AssocP {}
+
+protocol Base {
+  associatedtype T : AssocP
+}
+
+@available(*, unavailable)
+extension Base where T == ConcreteP {}

test/decl/protocol/req/recursion.swift

@@ -73,7 +73,7 @@ protocol PI {
 }
 
 struct SI<A: PI> : I where A : I, A.T == SI<A> {
-// expected-error@-1 5{{generic struct 'SI' has self-referential generic requirements}}
+// expected-error@-1 3{{generic struct 'SI' has self-referential generic requirements}}
   func ggg<T : I>(t: T.Type) -> T {
     return T()
   }
@@ -104,5 +104,5 @@ struct SU<A: P> where A.T == SU {
 }
 
 struct SIU<A: PI> : I where A : I, A.T == SIU {
-// expected-error@-1 5{{generic struct 'SIU' has self-referential generic requirements}}
+// expected-error@-1 3{{generic struct 'SIU' has self-referential generic requirements}}
 }

test/decl/protocol/unavailable.swift

@@ -6,7 +6,7 @@ protocol P {
 
 struct Type<Param> {}
 extension Type: P where Param: P, Param.A == Type<Param> {
-  // expected-error@-1 8{{extension of generic struct 'Type' has self-referential generic requirements}}
+  // expected-error@-1 6{{extension of generic struct 'Type' has self-referential generic requirements}}
   // expected-note@-2 6{{through reference here}}
   // expected-error@-3 {{type 'Type<Param>' does not conform to protocol 'P'}}
   typealias A = Param