Fix mangling for named opaque result types.

Author: DougGregor

lib/AST/ASTMangler.cpp

@@ -1558,7 +1558,17 @@ unsigned ASTMangler::appendBoundGenericArgs(DeclContext *dc,
 
     // If we are generic at this level, emit all of the replacements at
     // this level.
-    if (genericContext->isGeneric()) {
+    bool treatAsGeneric;
+    if (auto opaque = dyn_cast<OpaqueTypeDecl>(decl)) {
+      // For opaque type declarations, the generic parameters of the opaque
+      // type declaration are not part of the mangling, so check whether the
+      // naming declaration has generic parameters.
+      auto namedGenericContext = opaque->getNamingDecl()->getAsGenericContext();
+      treatAsGeneric = namedGenericContext && namedGenericContext->isGeneric();
+    } else {
+      treatAsGeneric = genericContext->isGeneric();
+    }
+    if (treatAsGeneric) {
       auto genericParams = subs.getGenericSignature().getGenericParams();
       unsigned depth = genericParams[currentGenericParamIdx]->getDepth();
       auto replacements = subs.getReplacementTypes();

test/IRGen/opaque_result_type.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %{python} %utils/chex.py < %s > %t/opaque_result_type.swift
-// RUN: %target-swift-frontend -enable-implicit-dynamic -disable-availability-checking -emit-ir %t/opaque_result_type.swift | %FileCheck --check-prefix=CHECK --check-prefix=CHECK-NODEBUG %t/opaque_result_type.swift
+// RUN: %target-swift-frontend -enable-experimental-named-opaque-types -enable-implicit-dynamic -disable-availability-checking -emit-ir %t/opaque_result_type.swift | %FileCheck --check-prefix=CHECK --check-prefix=CHECK-NODEBUG %t/opaque_result_type.swift
 
 // rdar://76863553
 // UNSUPPORTED: OS=watchos && CPU=x86_64
@@ -196,6 +196,18 @@ public func useFoo(x: String, y: C) {
 // CHECK: [[TYPE:%.*]] = call {{.*}} @__swift_instantiateConcreteTypeFromMangledName{{.*}}({{.*}} @"$s18opaque_result_type3baz1zQrx_tAA1PRzAA1QRzlFQOyAA1CCQo_MD")
 // CHECK: call swiftcc i8** @swift_getAssociatedConformanceWitness(i8** [[CONFORMANCE]], %swift.type* [[TYPE]]
 
+// Make sure we can mangle named opaque result types
+struct Boom<T: P> {
+  var prop1: Int = 5
+  var prop2: <U, V> (U, V) = ("hello", 5)
+}
+
+// CHECK-LABEL: define {{.*}} @"$s18opaque_result_type9gimmeBoomypyF
+// CHECK: call swiftcc void @"$s18opaque_result_type4BoomV5prop15prop2ACyxGSi_AcEQr_QrtvpQOyx_Qo__AcEQr_QrtvpQOyx_Qo0_ttcfcfA0_"
+public func gimmeBoom() -> Any {
+  Boom<String>(prop1: 5)
+}
+
 // CHECK-LABEL: define {{.*}} @"$sSS18opaque_result_type1PAA1AAaBP_AA1OPWT"
 // CHECK: [[OPAQUE:%.*]] = call {{.*}} @"$sSS18opaque_result_typeE3pooQryFQOMg"
 // CHECK: call swiftcc i8** @swift_getOpaqueTypeConformance(i8* {{.*}}, %swift.type_descriptor* [[OPAQUE]], [[WORD]] 1)