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

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

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:

https://gcc.gnu.org/g:98f29f5638f73d8e55590eba8098a537ba746287

commit r10-7233-g98f29f5638f73d8e55590eba8098a537ba746287
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Mar 18 00:23:39 2020 +0000

    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.

            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.