[4.2] IRGen: We need to make note of any parent decl in nested type decls

Such that we emit the parent's type metadata

rdar://39648725

Cherry-pick from #16135

Author: aschwaighofer

lib/IRGen/GenMeta.cpp

@@ -2424,6 +2424,8 @@ void irgen::emitClassMetadata(IRGenModule &IGM, ClassDecl *classDecl,
     IGM.addObjCClass(var,
               classDecl->getAttrs().hasAttribute<ObjCNonLazyRealizationAttr>());
   }
+
+  IGM.IRGen.noteUseOfAnyParentTypeMetadata(classDecl);
 }
 
 llvm::Value *IRGenFunction::emitInvariantLoad(Address address,
@@ -2820,6 +2822,19 @@ void irgen::emitStructMetadata(IRGenModule &IGM, StructDecl *structDecl) {
 
   IGM.defineTypeMetadata(declaredType, isIndirect, isPattern,
                          canBeConstant, init.finishAndCreateFuture());
+
+  IGM.IRGen.noteUseOfAnyParentTypeMetadata(structDecl);
+}
+
+void IRGenerator::noteUseOfAnyParentTypeMetadata(NominalTypeDecl *type) {
+  // If this is a nested type we also potentially might need the outer types.
+  auto *declCtxt = type->getDeclContext();
+  assert(declCtxt);
+  auto *parentNominalDecl = dyn_cast_or_null<NominalTypeDecl>(declCtxt);
+  if (!parentNominalDecl)
+    return;
+
+  noteUseOfTypeMetadata(parentNominalDecl);
 }
 
 // Enums
@@ -3024,6 +3039,8 @@ void irgen::emitEnumMetadata(IRGenModule &IGM, EnumDecl *theEnum) {
 
   IGM.defineTypeMetadata(declaredType, isIndirect, isPattern,
                          canBeConstant, init.finishAndCreateFuture());
+
+  IGM.IRGen.noteUseOfAnyParentTypeMetadata(theEnum);
 }
 
 llvm::Value *IRGenFunction::emitObjCSelectorRefLoad(StringRef selector) {

lib/IRGen/IRGenModule.h

@@ -357,6 +357,8 @@ class IRGenerator {
     noteUseOfTypeGlobals(type, false, requireMetadata);
   }
 
+  void noteUseOfAnyParentTypeMetadata(NominalTypeDecl *type);
+
 private:
   void noteUseOfTypeGlobals(NominalTypeDecl *type,
                             bool isUseOfMetadata,

test/multifile/Inputs/nested_types_defs.swift

@@ -0,0 +1,15 @@
+struct Outer {
+  struct Inner {
+  }
+}
+
+struct Outer2 {
+  enum InnerE {
+  }
+}
+
+struct Outer3 {
+  class InnerC {
+  }
+}
+

test/multifile/nested_types.swift

@@ -0,0 +1,21 @@
+// RUN: %target-build-swift -module-name test -wmo -O -emit-ir -Xfrontend -num-threads -Xfrontend 0 %s %S/Inputs/nested_types_defs.swift -o - | %FileCheck %s
+
+// Make sure we generate the outer metadata.
+
+// CHECK-DAG: @"$S4test6Outer3VMf" = internal constant {{.*}} @"$SytWV"{{.*}}@"$S4test6Outer3VMn"
+// CHECK-DAG: @"$S4test6Outer2VMf" = internal constant {{.*}} @"$SytWV"{{.*}}@"$S4test6Outer2VMn"
+// CHECK-DAG: @"$S4test6Outer3VMf" = internal constant {{.*}} @"$SytWV"{{.*}}@"$S4test6Outer3VMn"
+
+class C<T> { }
+
+struct Y {
+  let x:C<Outer.Inner>
+  let y:C<Outer2.InnerE>
+  let z:C<Outer3.InnerC>
+}
+
+public func test() {
+  var c = Y(x: C<Outer.Inner>(), y: C<Outer2.InnerE>(), z: C<Outer3.InnerC>())
+
+  print("a \(c)")
+}

test/multifile/nested_types/main.swift

@@ -0,0 +1,20 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-build-swift -wmo -O  %s %S/../Inputs/nested_types_defs.swift -o %t/a.out
+// RUN: %target-run %t/a.out | %FileCheck %s
+
+class C<T> { }
+
+struct Y {
+  let x:C<Outer.Inner>
+  let y:C<Outer2.InnerE>
+  let z:C<Outer3.InnerC>
+}
+
+func test() {
+  var c = Y(x: C<Outer.Inner>(), y: C<Outer2.InnerE>(), z: C<Outer3.InnerC>())
+
+  print("a \(c)")
+}
+
+// CHECK: a Y(x: a.C<a.Outer.Inner>, y: a.C<a.Outer2.InnerE>, z: a.C<a.Outer3.InnerC>)
+test()