[Bug c++/97052] Internal compiler error with substitution failure in template parameter list of concept declaration

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97052

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Patrick Palka
<ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:ebb734aac092cc1ea1208b3a96cc2b6ad85cf5a1

commit r10-9735-gebb734aac092cc1ea1208b3a96cc2b6ad85cf5a1
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue Apr 20 12:06:37 2021 -0400

    c++: ICE in dependent_type_p with constrained auto [PR97052]

    This patch fixes an "unguarded" call to coerce_template_parms in
    build_standard_check: processing_template_decl could be zero if we
    get here during processing of the first 'auto' parameter of an
    abbreviated function template, or if we're processing the type
    constraint of a non-templated variable.  In the testcase below, this
    leads to an ICE when coerce_template_parms instantiates C's dependent
    default template argument.

    gcc/cp/ChangeLog:

            PR c++/97052
            * constraint.cc (build_type_constraint): Temporarily increment
            processing_template_decl before calling build_concept_check.
            * pt.c (make_constrained_placeholder_type): Likewise.

    gcc/testsuite/ChangeLog:

            PR c++/97052
            * g++.dg/cpp2a/concepts-defarg2.C: New test.

    (cherry picked from commit c1c62aec6751678e958ab5c61b2d903a09d7efd9)