https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86654
--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #11)
> OK, so patch at least regresses
>
> FAIL: g++.dg/debug/dwarf2/lambda1.C -std=gnu++11 scan-assembler-times
> DW_TAG_variable[^.]*.ascii "this.0" 2
> FAIL: g++.dg/debug/dwarf2/lambda1.C -std=gnu++14 scan-assembler-times
> DW_TAG_variable[^.]*.ascii "this.0" 2
>
> but otherwise passes LTO bootstrap. Have to investigate the above tomorrow.
The reason is that in the late phase we fail DIE re-use and instead generate
a specification DIE because
if (((is_unit_die (old_die->die_parent)
/* This condition fixes the inconsistency/ICE with the
following Fortran test (or some derivative thereof) while
building libgfortran:
module some_m
contains
logical function funky (FLAG)
funky = .true.
end function
end module
*/
|| (old_die->die_parent
&& old_die->die_parent->die_tag == DW_TAG_module)
|| context_die == NULL)
...
subr_die = old_die;
triggers only because of context_die == NULL. This is a funky area
but the comment "For local class methods, this doesn't apply; we just use the
old DIE." suggests
|| local_scope_p (old_die->die_parent)
pre early-debug merge already had the context_die == NULL check which
_possibly_ was supposed to match that comment.
