[PATCH v2] c++/reflection: members_of and cv-qual class types [PR124215]

[Marek Polacek]

On Wed, Feb 25, 2026 at 11:08:43AM +0900, Jason Merrill wrote:
> On 2/25/26 5:13 AM, Marek Polacek wrote:
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > 
> > -- >8 --
> > Here when asking for the members of "^^Test const" we found nothing.
> > The reason is that members_of_representable_p checks whether
> > CP_DECL_CONTEXT != c, but if c is a type, it doesn't look at its
> > TYPE_MAIN_VARIANT.  Fixed as per Jakub's suggestion in the PR.
> > 
> >     PR c++/124215
> > 
> > gcc/cp/ChangeLog:
> > 
> >     * reflect.cc (class_members_of): Pass TYPE_MAIN_VARIANT of R to
> >     members_of_representable_p.
> 
> Would it make sense to r = TYPE_MAIN_VARIANT at the top of the function
> instead of doing it in the loop?

That works too!

Tested dg.exp on x86_64-pc-linux-gnu, ok for trunk?

-- >8 --
Here when asking for the members of "^^Test const" we found nothing.
The reason is that members_of_representable_p checks whether
CP_DECL_CONTEXT != c, but if c is a type, it doesn't look at its
TYPE_MAIN_VARIANT.  Fixed as per Jakub's suggestion in the PR.

        PR c++/124215

gcc/cp/ChangeLog:

        * reflect.cc (class_members_of): Use TYPE_MAIN_VARIANT of R.

gcc/testsuite/ChangeLog:

        * g++.dg/reflect/members_of9.C: New test.

Co-authored-by: Jakub Jelinek  <ja...@redhat.com>
---
 gcc/cp/reflect.cc                          |  1 +
 gcc/testsuite/g++.dg/reflect/members_of9.C | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/reflect/members_of9.C

diff --git a/gcc/cp/reflect.cc b/gcc/cp/reflect.cc
index 3c82251f511..871d52a55b1 100644
--- a/gcc/cp/reflect.cc
+++ b/gcc/cp/reflect.cc
@@ -6557,6 +6557,7 @@ class_members_of (location_t loc, const constexpr_ctx 
*ctx, tree r,
                  tree actx, tree call, bool *non_constant_p,
                  tree *jump_target, enum metafn_code kind, tree fun)
 {
+  r = TYPE_MAIN_VARIANT (r);
   if (kind == METAFN_MEMBERS_OF)
     {
       if (modules_p ())
diff --git a/gcc/testsuite/g++.dg/reflect/members_of9.C 
b/gcc/testsuite/g++.dg/reflect/members_of9.C
new file mode 100644
index 00000000000..9d07182953b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/reflect/members_of9.C
@@ -0,0 +1,17 @@
+// PR c++/124215
+// { dg-do compile { target c++26 } }
+// { dg-additional-options "-freflection" }
+
+#include <meta>
+
+struct Test {
+    int a;
+    char b;
+};
+
+consteval auto number_of_members(std::meta::info ty) -> size_t {
+    return nonstatic_data_members_of(ty, 
std::meta::access_context::current()).size();
+}
+
+static_assert(number_of_members(^^Test) == 2);
+static_assert(number_of_members(^^Test const) == 2);

base-commit: dda0023713e7bd8944255a8a4eba8c069e9a29fa
-- 
2.53.0