Sema: Change a few checkConformance() calls to lookupConformance()

Author: slavapestov

lib/Sema/DerivedConformanceCodable.cpp

@@ -269,7 +269,7 @@ static EnumDecl *validateCodingKeysType(const DerivedConformance &derived,
 
   // Ensure that the type we found conforms to the CodingKey protocol.
   auto *codingKeyProto = C.getProtocol(KnownProtocolKind::CodingKey);
-  if (!derived.getParentModule()->checkConformance(codingKeysType, codingKeyProto)) {
+  if (!derived.getParentModule()->lookupConformance(codingKeysType, codingKeyProto)) {
     // If CodingKeys is a typealias which doesn't point to a valid nominal type,
     // codingKeysTypeDecl will be nullptr here. In that case, we need to warn on
     // the location of the usage, since there isn't an underlying type to

lib/Sema/TypeCheckConcurrency.cpp

@@ -1049,7 +1049,7 @@ bool swift::diagnoseNonSendableTypes(
     return false;
 
   // FIXME: More detail for unavailable conformances.
-  auto conformance = module->checkConformance(type, proto);
+  auto conformance = module->lookupConformance(type, proto, /*allowMissing=*/true);
   if (conformance.isInvalid() || conformance.hasUnavailableConformance()) {
     return diagnoseSingleNonSendableType(
         type, fromContext, inDerivedConformance, loc, diagnose);

lib/Sema/TypeCheckProtocol.cpp

@@ -4339,9 +4339,9 @@ ConformanceChecker::resolveWitnessViaLookup(ValueDecl *requirement) {
         // a member that could in turn satisfy *this* requirement.
         auto derivableProto = cast<ProtocolDecl>(derivable->getDeclContext());
         auto conformance =
-            DC->getParentModule()->checkConformance(Adoptee, derivableProto);
+            DC->getParentModule()->lookupConformance(Adoptee, derivableProto);
         if (conformance.isConcrete()) {
-          (void)conformance.getConcrete()->getWitnessDecl(derivable);
+          (void) conformance.getConcrete()->getWitnessDecl(derivable);
         }
       }
     }

test/decl/protocol/req/witness_derived_other_conformance.swift

@@ -0,0 +1,17 @@
+// RUN: %target-typecheck-verify-swift
+
+protocol P {
+  func hash(into: inout Hasher)
+}
+
+// P.hash(into:) is witnessed by the S.hash(into:) that is synthesized
+// for the Hashable conformance.
+struct S: P, Hashable {}
+
+struct G<T> {}
+
+extension G: Equatable where T: Equatable {}
+extension G: Hashable where T: Hashable {}
+
+// Same here, but the conformance is conditional.
+extension G: P where T: P & Hashable {}