[Bug c++/126867] [16/17 regression] ICE after failed static_assert using __has_unique_object_representations in a concept since r16-5520

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126867

--- Comment #5 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-16 branch has been updated by Jakub Jelinek
<[email protected]>:

https://gcc.gnu.org/g:5e7fa6dbae546cdc07857be19cf3aa2375e9edad

commit r16-9552-g5e7fa6dbae546cdc07857be19cf3aa2375e9edad
Author: Jakub Jelinek <[email protected]>
Date:   Tue Aug 18 20:15:45 2026 +0200

    c++: Fix ICE during explanation of failed
__has_unique_object_representation [PR126867]

    The following testcase ICEs since r16-5520 added explain
    arguments to type_has_unique_obj_representations and
    record_has_unique_obj_representations.  Most of the location_t
    arguments in that change look correct, either DECL_SOURCE_LOCATION
    of some FIELD_DECL or in type_has_unique_obj_representations use
    loc, which is initialized to
      location_t loc = input_location;
      if (tree m = TYPE_MAIN_DECL (t))
        loc = DECL_SOURCE_LOCATION (m);
    But in record_has_unique_obj_representations we don't have
    a variable like that and t at that point is the RECORD_TYPE
    or UNION_TYPE, so using DECL_SOURCE_LOCATION on it will surely ICE
    in a checking compiler.
    location_of call does the above dances, so it seems easiest to
    call it rather than duplicate it by hand.

    2026-08-18  Jakub Jelinek  <[email protected]>

            PR c++/126867
            * tree.cc (record_has_unique_obj_representations): Use
            location_of (const_cast <tree> (t)) rather than
            DECL_SOURCE_LOCATION (t).

            * g++.dg/cpp1z/has-unique-obj-representations6.C: New test.

    Reviewed-by: Jason Merrill <[email protected]>
    (cherry picked from commit 318e6a4640420d5cc213df779bf751485fa56063)