Use TypeRepr::hasOpaque() consistently.

Replace shallow checks for `OpaqueReturnTypeRepr` with calls to
`hasOpaque`, which ensures that we consider opaque result types in
structural positions.

Author: DougGregor

lib/Parse/ParseDecl.cpp

@@ -6777,8 +6777,7 @@ Parser::parseDeclVar(ParseDeclOptions Flags,
 
     bool hasOpaqueReturnTy = false;
     if (auto typedPattern = dyn_cast<TypedPattern>(pattern)) {
-      hasOpaqueReturnTy =
-                        isa<OpaqueReturnTypeRepr>(typedPattern->getTypeRepr());
+      hasOpaqueReturnTy = typedPattern->getTypeRepr()->hasOpaque();
     }
     auto sf = CurDeclContext->getParentSourceFile();
 
@@ -7108,7 +7107,7 @@ ParserResult<FuncDecl> Parser::parseDeclFunc(SourceLoc StaticLoc,
                               CurDeclContext);
 
   // Let the source file track the opaque return type mapping, if any.
-  if (isa_and_nonnull<OpaqueReturnTypeRepr>(FuncRetTy) &&
+  if (FuncRetTy && FuncRetTy->hasOpaque() &&
       !InInactiveClauseEnvironment) {
     if (auto sf = CurDeclContext->getParentSourceFile()) {
       sf->addUnvalidatedDeclWithOpaqueResultType(FD);
@@ -7984,7 +7983,7 @@ Parser::parseDeclSubscript(SourceLoc StaticLoc,
   Subscript->getAttrs() = Attributes;
 
   // Let the source file track the opaque return type mapping, if any.
-  if (isa_and_nonnull<OpaqueReturnTypeRepr>(ElementTy.get()) &&
+  if (ElementTy.get() && ElementTy.get()->hasOpaque() &&
       !InInactiveClauseEnvironment) {
     if (auto sf = CurDeclContext->getParentSourceFile()) {
       sf->addUnvalidatedDeclWithOpaqueResultType(Subscript);

lib/Sema/TypeCheckGeneric.cpp

@@ -769,7 +769,7 @@ GenericSignatureRequest::evaluate(Evaluator &evaluator,
           return nullptr;
         }
       }();
-      if (resultTypeRepr && !isa<OpaqueReturnTypeRepr>(resultTypeRepr)) {
+      if (resultTypeRepr && !resultTypeRepr->hasOpaque()) {
         const auto resultType =
             resolution.withOptions(TypeResolverContext::FunctionResult)
                 .resolveType(resultTypeRepr);

test/IRGen/opaque_result_type.swift

@@ -62,7 +62,7 @@ public var globalProp: some O {
   return 0
 }
 
-public class C: P, Q {
+public class C: P, Q, Marker {
   // CHECK-LABEL: @"$s18opaque_result_type1CC3pooQryFQOMQ" = {{.*}} constant <{ {{.*}} }> <{
   // -- header: opaque type context (0x4), generic (0x80), unique (0x40), two entries (0x2_0000)
   // CHECK-SAME:         <i32 0x2_00c4>
@@ -154,6 +154,10 @@ func fizz<T: P & Q & Marker>(z: T) -> some P & Q & Marker {
   return z
 }
 
+func bauble<T: P & Q & Marker, U: Q>(z: T, u: U) -> [(some P & Q & Marker, (some Q)?)] {
+  return [(z, u)]
+}
+
 // Ensure the local type's opaque descriptor gets emitted.
 // CHECK-LABEL: @"$s18opaque_result_type11localOpaqueQryF0D0L_QryFQOMQ" = 
 func localOpaque() -> some P {
@@ -180,8 +184,12 @@ public func useFoo(x: String, y: C) {
   let pqb = pq.qoo()
   pqb.bar()
   pqb.baz()
+
+  let _ = bauble(z: y, u: y)
 }
 
+// CHECK-LABEL: define {{.*}} @"$s18opaque_result_type6bauble1z1uSayQr_QrSgtGx_q_tAA6MarkerRzAA1PRzAA1QRzAaIR_r0_lF"
+
 // CHECK-LABEL: define {{.*}} @"$s18opaque_result_type6useFoo1x1yySS_AA1CCtF"
 // CHECK: [[OPAQUE:%.*]] = call {{.*}} @"$s18opaque_result_type3baz1zQrx_tAA1PRzAA1QRzlFQOMg"
 // CHECK: [[CONFORMANCE:%.*]] = call swiftcc i8** @swift_getOpaqueTypeConformance(i8* {{.*}}, %swift.type_descriptor* [[OPAQUE]], [[WORD:i32|i64]] 1)