From cfdc5e297bbac3703f6b8ed61b85222f393d970a Mon Sep 17 00:00:00 2001
From: Nhat Nguyen <nhat7203@gmail.com>
Date: Thu, 31 Oct 2024 15:23:06 -0400
Subject: [PATCH] `type_of` metafunction should dealias the type (#93)

Fixes issue #91.
---
 clang/lib/AST/ExprConstantMeta.cpp            | 29 ++++++++++++++-----
 .../reflection/related-reflections.pass.cpp   |  6 ++--
 .../reflection/to-and-from-values.pass.cpp    |  6 ++--
 3 files changed, 28 insertions(+), 13 deletions(-)

diff --git a/clang/lib/AST/ExprConstantMeta.cpp b/clang/lib/AST/ExprConstantMeta.cpp
index 734194bbf06c70..a4af62a98d0db7 100644
--- a/clang/lib/AST/ExprConstantMeta.cpp
+++ b/clang/lib/AST/ExprConstantMeta.cpp
@@ -2069,14 +2069,19 @@ bool type_of(APValue &Result, ASTContext &C, MetaActions &Meta,
 
   switch (RV.getReflectionKind()) {
   case ReflectionKind::Null:
-  case ReflectionKind::Type:
+  case ReflectionKind::Type: {
+    QualType QT = desugarType(RV.getTypeOfReflectedResult(C), 
+                              /*UnwrapAliases=*/ true, /*DropCV=*/false,
+                              /*DropRefs=*/false);
+    return SetAndSucceed(Result, makeReflection(QT));
+  }
   case ReflectionKind::Template:
   case ReflectionKind::Namespace:
     return Diagnoser(Range.getBegin(), diag::metafn_no_associated_property)
         << DescriptionOf(RV) << 0 << Range;
   case ReflectionKind::Object: {
     QualType QT = desugarType(RV.getTypeOfReflectedResult(C),
-                              /*UnwrapAliases=*/false, /*DropCV=*/false,
+                              /*UnwrapAliases=*/ true, /*DropCV=*/false,
                               /*DropRefs=*/false);
     return SetAndSucceed(Result, makeReflection(QT));
   }
@@ -2094,20 +2099,21 @@ bool type_of(APValue &Result, ASTContext &C, MetaActions &Meta,
 
     bool UnwrapAliases = isa<ParmVarDecl>(VD) || isa<BindingDecl>(VD);
     bool DropCV = isa<ParmVarDecl>(VD);
-    QualType QT = desugarType(VD->getType(), UnwrapAliases, DropCV,
+    QualType QT = desugarType(VD->getType(), 
+                              /*UnwrapAliases=*/ true, DropCV,
                               /*DropRefs=*/false);
     return SetAndSucceed(Result, makeReflection(QT));
   }
   case ReflectionKind::BaseSpecifier: {
     QualType QT = RV.getReflectedBaseSpecifier()->getType();
-    QT = desugarType(QT, /*UnwrapAliases=*/false, /*DropCV=*/false,
+    QT = desugarType(QT, /*UnwrapAliases=*/true, /*DropCV=*/false,
                      /*DropRefs=*/false);
     return SetAndSucceed(Result, makeReflection(QT));
   }
   case ReflectionKind::DataMemberSpec:
   {
     QualType QT = RV.getReflectedDataMemberSpec()->Ty;
-    QT = desugarType(QT, /*UnwrapAliases=*/false, /*DropCV=*/false,
+    QT = desugarType(QT, /*UnwrapAliases=*/true, /*DropCV=*/false,
                      /*DropRefs=*/false);
     return SetAndSucceed(Result, makeReflection(QT));
   }
@@ -5618,12 +5624,19 @@ bool return_type_of(APValue &Result, ASTContext &C, MetaActions &Meta,
     return true;
 
   switch (RV.getReflectionKind()) {
-  case ReflectionKind::Type:
-    if (auto *FPT = dyn_cast<FunctionProtoType>(RV.getReflectedType()))
-      return SetAndSucceed(Result, makeReflection(FPT->getReturnType()));
+  case ReflectionKind::Type: {
+    if (auto *FPT = dyn_cast<FunctionProtoType>(RV.getReflectedType())) {
+      QualType QT =
+          desugarType(FPT->getReturnType(), /*UnwrapAliases=*/ true, /*DropCV=*/false,
+                      /*DropRefs=*/false);
+      return SetAndSucceed(Result, makeReflection(QT));
+    }
 
     return Diagnoser(Range.getBegin(), diag::metafn_cannot_introspect_type)
         << 3 << 2 << Range;
+  }
+
+
   case ReflectionKind::Declaration:
     if (auto *FD = dyn_cast<FunctionDecl>(RV.getReflectedDecl());
         FD && !isa<CXXConstructorDecl>(FD) && !isa<CXXDestructorDecl>(FD))
diff --git a/libcxx/test/std/experimental/reflection/related-reflections.pass.cpp b/libcxx/test/std/experimental/reflection/related-reflections.pass.cpp
index 4f373b75f7122b..8b6d76408f5abd 100644
--- a/libcxx/test/std/experimental/reflection/related-reflections.pass.cpp
+++ b/libcxx/test/std/experimental/reflection/related-reflections.pass.cpp
@@ -32,8 +32,8 @@ extern int_alias ia;
 extern decltype(int_alias{}) dtia;
 
 static_assert(type_of(^^i) == ^^int);
-static_assert(type_of(^^ia) == ^^int_alias);
-static_assert(type_of(^^ia) != ^^int);
+static_assert(type_of(^^ia) != ^^int_alias);
+static_assert(type_of(^^ia) == ^^int);
 static_assert(type_of(^^dtia) == ^^int);
 static_assert(type_of(^^dtia) != ^^int_alias);
 static_assert(^^int_alias != ^^int);
@@ -43,7 +43,7 @@ constexpr auto a = data_member_spec(^^int, {});
 constexpr auto b = data_member_spec(^^int_alias, {});
 
 static_assert(type_of(a) == ^^int);
-static_assert(type_of(b) == ^^int_alias);
+static_assert(type_of(b) != ^^int_alias);
 }  // namespace expression_type
 
                               // ================
diff --git a/libcxx/test/std/experimental/reflection/to-and-from-values.pass.cpp b/libcxx/test/std/experimental/reflection/to-and-from-values.pass.cpp
index 048c5ac553622c..d3723045a26b19 100644
--- a/libcxx/test/std/experimental/reflection/to-and-from-values.pass.cpp
+++ b/libcxx/test/std/experimental/reflection/to-and-from-values.pass.cpp
@@ -215,12 +215,14 @@ struct S{};
 
 using Alias1 = int;
 constexpr Alias1 a1 = 3;
-static_assert(type_of(^^a1) == ^^const Alias1);
+static_assert(type_of(^^a1) != ^^const Alias1);
+static_assert(type_of(^^a1) == ^^const int);
 static_assert(type_of(value_of(^^a1)) == ^^int);
 
 using Alias2 = S;
 constexpr Alias2 a2 {};
-static_assert(type_of(^^a2) == ^^const Alias2);
+static_assert(type_of(^^a2) != ^^const Alias2);
+static_assert(type_of(^^a2) == ^^const S);
 static_assert(type_of(value_of(^^a2)) == ^^const S);
 
 constexpr const int &ref = a1;