[Bug c++/99850] [P1102R2] reject valid lambda syntax in C++23

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99850

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:784de5292c34e287c848b382b431599b818ea76e

commit r11-8210-g784de5292c34e287c848b382b431599b818ea76e
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Apr 16 09:34:26 2021 +0200

    c++: Fix up C++23 [] <...> requires primary -> type {} parsing [PR99850]

    The requires clause parsing has code to suggest users wrapping
    non-primary expressions in (), so if it e.g. parses a primary expression
    and sees it is followed by ++, --, ., ( or -> among other things it
    will try to reparse it as assignment expression or what and if that works
    suggests wrapping it inside of parens.
    When it is requires-clause that is after <typename T> etc. it already
    has an exception from that as ( can occur in valid C++20 expression there
    - starting the parameters of the lambda.
    In C++23 another case can occur, as the parameters with the ()s can be
    omitted, requires C can be followed immediately by -> which starts a
    trailing return type.  Even in that case, we don't want to parse that
    as C->...

    2021-04-16  Jakub Jelinek  <jakub@redhat.com>

            PR c++/99850
            * parser.c (cp_parser_constraint_requires_parens) <case CPP_DEREF>:
            If lambda_p, return pce_ok instead of pce_maybe_postfix.

            * g++.dg/cpp23/lambda-specifiers2.C: New test.