[Bug c++/124399] [reflection] meta::annotations_of issue

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124399

--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:9c483886957cac7016dc404c2b6aab2ae94574a9

commit r16-7992-g9c483886957cac7016dc404c2b6aab2ae94574a9
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Mar 10 21:27:10 2026 +0100

    c++: For reflection comparison of annotations compare TREE_VALUE [PR124399]

    https://eel.is/c++draft/meta.reflection#annotation-4
    testcase also contains
    [[=1]] int x, y;
    static_assert(annotations_of(^^x)[0] == annotations_of(^^y)[0]);
    so in case of an annotation shared by multiple declarations we need
    to compare the TREE_VALUE of the attributes (which is shared in that
    case) rather than the TREE_LIST with that TREE_VALUE and TREE_PURPOSE
    being "internal ":"annotation ".
    For mangling we already handle it right:
      if (eval_is_annotation (h, kind) == boolean_true_node)
        {
          strcpy (prefix, "an");
          if (TREE_PURPOSE (TREE_VALUE (h)) == NULL_TREE)
            TREE_PURPOSE (TREE_VALUE (h))
              = build_int_cst (integer_type_node, annotation_idx++);
          return TREE_PURPOSE (TREE_VALUE (h));
        }
    so the annotation index is stored on TREE_PURPOSE of the TREE_VALUE,
    so in shared annotation like the above it will have the same index
    in both cases.

    Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

    When I was adding further tests for this, I've noticed that we don't
    handle correctly
    [[=1]] int x [[=2]], y [[=3]];
    because the attributes list which is shared is clearly added as a shared
    tail of the other attributes.  For now this is commented out in the
    test, will try to deal with it somehow incrementally.

    2026-03-10  Jakub Jelinek  <jakub@redhat.com>

            PR c++/124399
            * reflect.cc (compare_reflections): For REFLECT_ANNOTATION, compare
            TREE_VALUE of lhs and rhs instead of lhs and rhs.

            * g++.dg/reflect/annotations12.C: Add further tests.