msvc compile error C7631

[UMU618]

After I upgrading msvc to latest version, get error C7631.

• Microsoft Visual Studio Community 2022 (64-bit) - Version 17.5.0

• Boost 1.81.0

boost\boost\log\keywords\severity.hpp(32,1): error C7631: 'boost::log::v2_mt_nt6::keywords::`anonymous-namespace'::severity': variable with internal linkage declared but not defined

[UMU618]

Boost is compiled with b2.exe cxxstd=20 link=shared runtime-link=shared address-model=64 define=_WIN32_WINNT=0x0601

[UMU618]

https://github.com/boostorg/parameter/blob/develop/include/boost/parameter/keyword.hpp#L716

    namespace                                                                \
    {                                                                        \
        ::boost::parameter::keyword<tag_namespace::name> const& name         \
            = ::boost::parameter::keyword<tag_namespace::name>::instance;    \
    }

Add static to this line can fix this issue.

[Lastique]

This seems to be a compiler bug because severity is the variable definition, given that it has initializer.

Please report this to MSVC developers.

[UMU618]

Already report here

[Lastique]

I have tried to build the current develop with the command you provided (plus toolset=msvc-14.3) and couldn't reproduce the error.

Could you provide a reproducer?

[UMU618]

Sorry, I can't. This problem only arises when the code is sufficiently complex. Our projects have lots of C++ 20 modules, *.ixx. I use Boost.Log in small project, it compiles.

[Patschkowski]

As the previous thread was closed by Microsoft due to not enough input being provided by the author, I opened a new one with a small reproducer:

https://developercommunity.visualstudio.com/t/error-C7631:-when-instantiating-template/10476144

[Patschkowski]

As the previous thread was closed by Microsoft due to not enough input being provided by the author, I opened a new one with a small reproducer:

https://developercommunity.visualstudio.com/t/error-C7631:-when-instantiating-template/10476144

Microsoft responded that this is not a compiler bug.