[Bug c++/93140] [8/9 Regression] Segfault in cc1plus on incorrect decltype among function args

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93140

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jason Merrill
<jason@gcc.gnu.org>:

https://gcc.gnu.org/g:1a8996b0a7b238180f4a10b19b1e90b33e5b2df0

commit r9-8291-g1a8996b0a7b238180f4a10b19b1e90b33e5b2df0
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Feb 26 13:03:23 2020 -0500

    c++: Fix decltype of empty pack expansion of parm.

    In unevaluated context, we only substitute a single PARM_DECL, not the
    entire chain, but the handling of an empty pack expansion was missing that
    check.

    gcc/cp/ChangeLog
    2020-02-26  Jason Merrill  <jason@redhat.com>

        PR c++/93140
        * pt.c (tsubst_decl) [PARM_DECL]: Check cp_unevaluated_operand in
        handling of TREE_CHAIN for empty pack.