[Bug libstdc++/94203] experimental/executor and socket header issues-

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94203

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:942b32e261c414a033766ed7848d923f9630b991

commit r9-8543-g942b32e261c414a033766ed7848d923f9630b991
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Fri Apr 24 14:29:37 2020 +0100

    libstdc++: Fix type-erasure in experimental::net::executor (PR 94203)

    The _Tgt and _TgtImpl types that implement type-erasure didn't agree on
    the virtual interface, so failed as soon as they were instantiated. With
    Clang they failed even sooner. The interface was also dependent on
    whether RTTI was enabled or not.

    This patch fixes the broken virtual functions and makes the type work
    without RTTI, by using a pointer to a specialization of a function
    template (similar to the approaches in std::function and std::any).

    The changes to the virtual functions would be an ABI change, except that
    the previous code didn't even compile if instantiated. This is
    experimental TS material anyway.

    Backport from mainline
    2020-03-18  Jonathan Wakely  <jwakely@redhat.com>

            PR libstdc++/94203
            * include/experimental/executor (executor::executor(Executor)):
Call
            make_shared directly instead of _M_create. Create _Tgt1 object.
            (executor::executor(allocator_arg_t, const ProtoAlloc&, Executor)):
            Call allocate_shared directly instead of _M_create. Create _Tgt2
            object.
            (executor::target_type): Add cast needed for new _Tgt interface.
            (executor::target): Define when RTTI is disabled. Use
_Tgt::_M_func.
            (executor::_Tgt): Define the same interface whether RTTI is enabled
or
            not.
            (executor::_Tgt::target_type, executor::_Tgt::target): Do not use
            std::type_info in the interface.
            (executor::_Tgt::_M_func): Add data member.
            (executor::_TgtImpl): Replace with _Tgt1 and _Tgt2 class templates.
            (executor::_Tgt1::_S_func): Define function to access target
without
            depending on RTTI.
            (executor::_M_create): Remove.
            (operator==, operator!=): Simplify comparisons for executor.
            * include/experimental/socket (is_error_code_enum<socket_errc>):
            Define specialization before use.
            * testsuite/experimental/net/executor/1.cc: New test.