[committed] libstdc++: Add default constructor to net::service_already_exists (PR 94199)

[Jonathan Wakely]

On 17/03/20 12:01 +0100, Christophe Lyon wrote:
>Hi,
>
>
>On Mon, 16 Mar 2020 at 23:54, Jonathan Wakely via Gcc-patches
><gcc-patches@gcc.gnu.org> wrote:
>>
>> The service_already_exists exception type specified in the TS doesn't
>> have any constructors defined. Since its base class isn't default
>> constructible, that means has no usable constructors. This may be a
>> defect in the TS.
>>
>> This patch fixes it by adding a default constructor, but making it
>> private. The make_service function is declared as a friend to be able to
>> call that private constructor.
>>
>>         PR libstdc++/94199
>>         * include/experimental/executor (service_already_exists): Add default
>>         constructor. Declare make_service to be a friend.
>>         * testsuite/experimental/net/execution_context/make_service.cc: New
>>         test.
>>
>
>The new test fails on arm-eabi / aarch64-elf (aka bare-metal / newlib
>targets), because:
>/arm-none-eabi/libstdc++-v3/include/experimental/executor:514: error:
>'mutex' in namespace 'std' does not name a type
>/arm-none-eabi/libstdc++-v3/include/experimental/executor:561: error:
>'mutex' is not a member of 'std'
>[...]
>
>I don't remember what's the usual "fix" for this

I think they are just failing on some targets:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89760