[Bug c++/106969] [12/13 Regression] member function constness incorrectly propagates to local class member function return type deduction

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106969

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:bbf2424c57c2e13d1a972c4ef4e871c3119b9cb4

commit r13-6856-gbbf2424c57c2e13d1a972c4ef4e871c3119b9cb4
Author: Patrick Palka <ppalka@redhat.com>
Date:   Fri Mar 24 14:51:24 2023 -0400

    c++: outer 'this' leaking into local class [PR106969]

    Here when resolving the implicit object for '&wrapped' within the
    local class Foo, we expect to obtain a dummy object of type Foo& since
    there's no 'this' available in this context.  And yet at this point
    current_class_ref still corresponds to the outer class Context (and is
    const), which confuses maybe_dummy_object into propagating the cv-quals
    of current_class_ref and returning an object of type const Foo&.  Thus
    decltype(&wrapped) wrongly yields const int* instead of int*.

    The problem ultimately seems to be that the 'this' from the enclosing
    class appears available for use when parsing the local class, but 'this'
    shouldn't persist across classes like that.  This patch fixes this by
    clearing current_class_ptr/ref before parsing a class definition.

    After this change, for the test name-clash11.C in C++98 mode we would
    now complain about an invalid use of 'this' in e.g.

      ASSERT (sizeof (this->A) == 16);

    due to the way the test defines the ASSERT macro via a local class.
    This patch redefines the macro using a local typedef instead.

            PR c++/106969

    gcc/cp/ChangeLog:

            * parser.cc (cp_parser_class_specifier): Clear current_class_ptr
            and current_class_ref sooner, before parsing a class definition.

    gcc/testsuite/ChangeLog:

            * g++.dg/lookup/name-clash11.C: Fix ASSERT macro definition in
            C++98 mode.
            * g++.dg/lookup/this2.C: New test.