[Bug c++/99806] [10 Regression] ICE: in tsubst_copy, at cp/pt.c:17247

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99806

--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Marek Polacek
<mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:8f4f2fbc17c2a225c29ea20a2b6046cbdc7b3155

commit r10-9691-g8f4f2fbc17c2a225c29ea20a2b6046cbdc7b3155
Author: Marek Polacek <polacek@redhat.com>
Date:   Thu Apr 8 14:39:28 2021 -0400

    c++: Fix two issues with auto function parameter [PR99806]

    When we have a member function with auto parameter like this:

      struct S {
        void f(auto);
      };

    cp_parser_member_declaration -> grokfield produces a FUNCTION_DECL
    "void S::foo(auto:1)", and then finish_fully_implicit_template turns
    that FUNCTION_DECL into a TEMPLATE_DECL.  The bug here is that we only
    call cp_parser_save_default_args for a FUNCTION_DECL.  As a consequence,
    abbrev10.C is rejected because we complain that the default argument has
    not been defined, and abbrev11.C ICEs, because we don't re-parse the
    delayed noexcept, so the DEFERRED_PARSE tree leaks into tsubst* where we
    crash.  This patch fixes both issues.

    gcc/cp/ChangeLog:

            PR c++/99806
            * parser.c (cp_parser_member_declaration): Call
            cp_parser_save_default_args even for function templates.  Use
            STRIP_TEMPLATE on the declaration we're passing.

    gcc/testsuite/ChangeLog:

            PR c++/99806
            * g++.dg/concepts/abbrev10.C: New test.
            * g++.dg/concepts/abbrev11.C: New test.

    (cherry picked from commit 625dadaf5df5a2ae0d8c5660fd1eec8ba354479c)