<field> is not a member of <class> but is

[pearl frigate]

Hello, does anyone have an idea why Clang thinks that _promise is not a member of the Awaiter class:

template <typename T>
struct _Task {
    // ...
    struct promise_type {
        // ...
        auto final_suspend() noexcept {
            struct Awaiter {
                promise_type *_promise;

                void await_suspend(std::coroutine_handle<void>) noexcept {
                    auto cfp = std::exchange(_promise->_cfp, Cfp::PAST_SUSPEND);
                    if (cfp == Cfp::PAST_START)
                        _promise->_resume->resume();
                }
    // ...

Compilation command & output:

clang++ -c -o .cutekit/build/efi-x86_64-2f159776/karm-base-tests/__obj__/test-async.cpp.o src/libs/karm-base/tests/test-async.cpp -MD -MF .cutekit/build/efi-x86_64-2f159776/karm-base-tests/__obj__/test-async.cpp.o.d -std=gnu++2b -Wall -Wextra -Werror -fcolor-diagnostics -fno-exceptions -fno-rtti -target x86_64-unknown-windows -ffreestanding -fno-stack-protector -fshort-wchar -mno-red-zone -I.cutekit/extern/cute-engineering -I.cutekit/extern/cute-engineering/ce-libc/src/ce-libc -I.cutekit/extern/cute-engineering/ce-libm/src/ce-libm -I.cutekit/extern/cute-engineering/ce-stdcpp/src/ce-stdcpp -Isrc/apps -Isrc/assets -Isrc/impls -Isrc/kernel -Isrc/libs -Isrc/specs -Isrc/web -D__ck_abi_ms__ -D__ck_abi_value=ms -D__ck_arch_value=x86_64 -D__ck_arch_x86_64__ -D__ck_karm_sys_encoding_utf16__ -D__ck_karm_sys_encoding_value=utf16 -D__ck_karm_sys_line_ending_crlf__ -D__ck_karm_sys_line_ending_value=crlf -D__ck_karm_sys_path_separator_backslash__ -D__ck_karm_sys_path_separator_value=backslash -D__ck_sys_efi__ -D__ck_sys_value=efi -D__ck_toolchain_clang__ -D__ck_toolchain_value=clang -D__ck_version_'24_01'__ -D__ck_version_value='24.01'
In file included from src/libs/karm-base/tests/test-async.cpp:1:
src/libs/karm-base/async.h:358:46: error: 'Karm::Async::_Task<int>::promise_type::final_suspend()::Awaiter::await_suspend(std::coroutine_handle<void>)::Awaiter::_promise' is not a member of class 'Awaiter'
                    auto cfp = std::exchange(_promise->_cfp, Cfp::PAST_SUSPEND);
                                             ^
src/libs/karm-base/async.h:350:20: note: in instantiation of member function 'Karm::Async::_Task<int>::promise_type::final_suspend()::Awaiter::await_suspend' requested here
            struct Awaiter {
                   ^
src/libs/karm-base/async.h:360:25: error: 'Karm::Async::_Task<int>::promise_type::final_suspend()::Awaiter::await_suspend(std::coroutine_handle<void>)::Awaiter::_promise' is not a member of class 'Awaiter'
                        _promise->_resume->resume();
                        ^
2 errors generated.

Full context:

https://github.com/skift-org/skift/blob/main/src/libs/karm-base/async.h#L358

[chilly tangle]

When your question is answered use !solved to mark the question as resolved.

Remember to ask specific questions, provide necessary details, and reduce your question to its simplest form. For tips on how to ask a good question use !howto ask.

[tacit frost]

try

this->_prom->_resume->resume();

or

Awaiter::_prom->_resume->resume();

[pearl frigate]

Awaiter:: doesn't work but this-> does work, but now the question is why

[tacit frost]

define "Awaiter:: doesnt work"

show the build log

[pearl frigate]

I get the same error message

In file included from src/libs/karm-base/tests/test-async.cpp:1:
src/libs/karm-base/async.h:358:55: error: 'Karm::Async::_Task<int>::promise_type::final_suspend()::Awaiter::await_suspend(std::coroutine_handle<void>)::Awaiter::_promise' is not a member of class 'Awaiter'
                    auto cfp = std::exchange(Awaiter::_promise->_cfp, Cfp::PAST_SUSPEND);
                                             ~~~~~~~~~^
src/libs/karm-base/async.h:350:20: note: in instantiation of member function 'Karm::Async::_Task<int>::promise_type::final_suspend()::Awaiter::await_suspend' requested here
            struct Awaiter {
                   ^
src/libs/karm-base/async.h:360:34: error: 'Karm::Async::_Task<int>::promise_type::final_suspend()::Awaiter::await_suspend(std::coroutine_handle<void>)::Awaiter::_promise' is not a member of class 'Awaiter'
                        Awaiter::_promise->_resume->resume();
                        ~~~~~~~~~^
2 errors generated.

[tacit frost]

that's because Awaiter is not a global class, Awaiter is a very very nested class

the className::fieldName syntax is meant for inheritance field name duplicates, so just use the this and you should be good to go

so, to make the full class name work...

one moment...

::Karm::Async::_Task<T>::promise_type::final_suspend()::Awaiter::_prom
this shit?

hahaha

[pearl frigate]

This still doesn't explain why the bare _promise doesn't work, also it seems to work if I don't put -target x86_64-unknown-windows in my command line So the plot thicken

[tacit frost]

I mean, you decided to use these disgusting nested classes mate, now be a good boy and use this

[pearl frigate]

No, I won't!

[tacit frost]

then this fate awaits you:

https://tenor.com/view/kaboom-boom-nuke-nuclear-bomb-gif-20734003

oh yeah, local classes' type cannot be accessed, no matter how hard you try, only nested classes' type can be accessed.

[tacit frost]

so this wont work cause final_suspend() is treated like a call to a static function, and from there the scope resolution operator just doesn't work

@pearl frigate

template<typename T>
struct Sample
{
    int num;

    struct Nested
    {
        void func()
        {
            struct Dummy
            {
                int x;
            
                int f1()
                {
                    return Dummy::x;
                }

                int f2() { return this->x; }

                int f3() { return x; }
            };
        }
    };
};

int main()
{
    
}

this compiles, so why your build doesn't accept all the options is questionable

[pearl frigate]

Doesn't work either https://godbolt.org/z/6YYMsas9E

[tacit frost]

GCC accepts this, clang doesn't

lmfao

[pearl frigate]

clang accept it if you remove the -target x86_64-unknown-windows option

or the template at the top level

[tacit frost]

ummmmmmmmmmmm, so what do clang docs say about this compiler arg

https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-target

marvelous

AND USELESS

[tacit frost]

yeah this is beyond me, go in #tooling and ask about this cursed clang++ target that you chose

[pearl frigate]

A well reduced version of the exemple https://godbolt.org/z/9sE5hvW7f

[tacit frost]

go to #tooling

[pearl frigate]

Found it! https://clang.llvm.org/docs/MSVCCompatibility.html

[chilly tangle]

Thank you and let us know if you have any more questions!

This thread is now set to auto-hide after an hour of inactivity

[tacit frost]

so what is the answer, is this->fieldName the only valid thing?

why is clang doing this?

[pearl frigate]

No clang emulates MSVC bugs when targeting windows and fieldName is valids

[tacit frost]

hahahahahahaha, emulating MSVC bugs in the name of ABI compatibility, meme of the month

🎉 🎉 🎉