Compile failure with WinRT on 2.4.5

[bnason-nf]

Hi,

I just updated to version 2.4.5, and the Windows UWP build using doctest gets this compile error:

doctest\doctest/doctest.h(3070,41): error C2482: 'tlsLaneIdx': dynamic initialization of thread local data not allowed in WinRT code
doctest\doctest/doctest.h(3068): message : while compiling class template member function 'std::atomic<int> &doctest::detail::MultiLaneAtomic<int>::myAtomic(void) noexcept'
doctest\doctest/doctest.h(3025): message : see reference to function template instantiation 'std::atomic<int> &doctest::detail::MultiLaneAtomic<int>::myAtomic(void) noexcept' being compiled
doctest\doctest/doctest.h(3084): message : see reference to class template instantiation 'doctest::detail::MultiLaneAtomic<int>' being compiled

This error is documented here:
https://docs.microsoft.com/en-us/cpp/error-messages/compiler-errors-1/compiler-error-c2482

It's trivial to avoid the error by splitting the declaration and the assignment, but I'm not sure this code is doing what you intend since the variable isn't static, or maybe I'm misunderstanding.

Thanks,
Benbuck

[onqtam]

Hi,

thread_local implies static when used in function-scope so that code should be fine.

Regarding your problem - the documentation you link to states that A static expression is required to initialize __declspec(thread) or thread_local data in these runtime environments. so I guess the problem is that laneCounter++ % DOCTEST_MULTI_LANE_ATOMICS_THREAD_LANES is not a static expression and that's not permitted in that environment.

What you could do is simply define DOCTEST_CONFIG_NO_MULTI_LANE_ATOMICS before including the framework header. Perhaps the framework can detect Windows UWP and define that by itself - I'm open for PRs :)

Let me know if this helps!

[bnason-nf]

Hi Viktor,

Defining DOCTEST_CONFIG_NO_MULTI_LANE_ATOMICS does avoid the problem. I'm not sure what the actual solution would be if you wanted to support that feature under WinRT, but the workaround is sufficient for my needs.

Thanks,
Benbuck

[onqtam]

Seems that other people are having problems with this as well: jupyter-xeus/cpp-terminal#88

Assuming there is a macro to detect WinRT (something like __cplusplus_winrt or anything mentioned here) it should be possible to simply add

#ifdef SOME_WINRT_MACRO
#define DOCTEST_CONFIG_NO_MULTI_LANE_ATOMICS
#endif

But someone else should test this as I don't have access to a Windows machine atm.

[bnason-nf]

Hi @onqtam,

This seems to be the right way to do the ifdef:

#if defined(WINAPI_FAMILY) && (WINAPI_FAMILY == WINAPI_FAMILY_APP)
#define DOCTEST_CONFIG_NO_MULTI_LANE_ATOMICS
#endif

Would that be something you would be willing to add into doctest itself?

Thanks,
Benbuck

[onqtam]

Thanks! fixed in the dev branch