[Bug c++/123376] [16 Regression] ICE in write_type when building qt6-qtscxml with -flto -ffat-lto-objects since r16-3821

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123376

--- Comment #11 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:b227c79c4331acdf1f1928b7a01ba3c03e00e6cb

commit r16-7070-gb227c79c4331acdf1f1928b7a01ba3c03e00e6cb
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Jan 27 11:29:27 2026 +0100

    debug/123376 - mangle decls referenced in initializers early

    The following makes sure to mangle decls referenced in initializers,
    even when of aggregate type, during the early debug phase since
    later we eventually leave stray supposedly unused CV qualified
    types as their own main variant which confuses C++ mangling.  The
    comment that refers to rtl_for_decl_init punting might be
    accurate, but loc_list_from_tree_1 will happily see to
    cst_pool_loc_descr where constant pool lookup will eventually
    create DECL_RTL of referenced symbols, triggering mangling.

            PR debug/123376
            * dwarf2out.cc (tree_add_const_value_attribute): Walk all
            initializers for early mangling of referenced decls.
            (mangle_referenced_decls): Also walk subtrees of CONSTRUCTORS.

            * g++.dg/lto/pr123376_0.C: New testcase.