Clang + libstdc++-16 fail: no matching member function for call to 'emplace'

[AngryLoki]

Steps to reproduce

Hi, there is some new code which fails to compile when compiler is set to clang-21 with newest libstdc++-16 (from git):

/var/tmp/portage/net-im/telegram-desktop-6.2.3/work/tdesktop-6.2.3-full/Telegram/SourceFiles/inline_bots/bot_attach_web_view.cpp:1406:23: error: no matching member function for call to 'emplace'
 1406 |                 _botFullWaitingArgs.emplace();
      |                 ~~~~~~~~~~~~~~~~~~~~^~~~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/g++-v16/optional:1126:2: note: candidate template ignored: requirement 'is_constructible_v<InlineBots::WebViewInstance::ShowArgs>' was not satisfied [with _Args = <>]
 1126 |         emplace(_Args&&... __args)
      |         ^
/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/g++-v16/optional:1138:2: note: candidate function template not viable: requires at least argument '__il', but no arguments were provided
 1138 |         emplace(initializer_list<_Up> __il, _Args&&... __args)
      |         ^       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Apparently, as InlineBots::WebViewInstance::ShowArgs is private nested struct, it is not considered as constructible, see https://stackoverflow.com/questions/60490574/stdis-constructible-returns-inconsistent-value-for-private-constructor

One possible solution is to use _botFullWaitingArgs = ShowArgs{};, see attached PR.

Also please check and merge related PR TelegramMessenger/tgcalls#50, if you want to compile it.

Expected behaviour

It compiles.

Actual behaviour

It fails to compile.

Operating system

Gentoo

Version of Telegram Desktop

6.2.3

Installation source

Other (unofficial) source

Crash ID

No response

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