bit_cast: ambiguous call to overloaded function

[Dennis]

Compiling with MSVC 14.28.29910 and C++20 I am getting the following compile error. I have not managed to create a minimal example, but since std::bit_cast is available now it probably makes sense to switch to it in any case.

[build] C:\Boost\include\boost-1_76\boost\outcome\experimental\status-code\config.hpp(271): error C2668: 'system_error2::detail::bit_cast': ambiguous call to overloaded function
[build] C:\Boost\include\boost-1_76\boost\outcome\experimental\status-code\config.hpp(216): note: could be 'To system_error2::detail::bit_cast<To,From,true>(const From &) noexcept'
[build]         with
[build]         [
[build]             To=__int64,
[build]             From=AllocatedValue<15524508317838324489,std::string>
[build]         ]
[build] C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29910\include\bit(33): note: or       '_To std::bit_cast<To,From,0>(const _From &) noexcept' [found using argument-dependent lookup]
[build]         with
[build]         [
[build]             _To=__int64,
[build]             To=__int64,
[build]             From=AllocatedValue<15524508317838324489,std::string>,
[build]             _From=AllocatedValue<15524508317838324489,std::string>
[build]         ]
[build] C:\Boost\include\boost-1_76\boost\outcome\experimental\status-code\config.hpp(271): note: while trying to match the argument list '(const From)'
[build]         with
[build]         [
[build]             From=AllocatedValue<15524508317838324489,std::string>
[build]         ]
[build] C:\Boost\include\boost-1_76\boost\outcome\experimental\status-code\status_code.hpp(543): note: see reference to function template instantiation 'To system_error2::detail::erasure_cast<__int64,AllocatedValue<15524508317838324489,std::string>,true>(const From &) noexcept' being compiled
[build]         with
[build]         [
[build]             To=__int64,
[build]             From=AllocatedValue<15524508317838324489,std::string>
[build]         ]
[build] C:\src\outcome/stringStatusCode.h(5): note: see reference to function template instantiation 'system_error2::status_code<system_error2::erased<intptr_t,true>>::status_code<Derived,true>(system_error2::status_code<Derived> &&) noexcept' being compiled
[build]         with
[build]         [
[build]             Derived=BasicStringStatusCodeDomain<15524508317838324489>
[build]         ]
[build] C:\src\outcome/stringStatusCode.h(5): note: see reference to function template instantiation 'system_error2::status_code<system_error2::erased<intptr_t,true>>::status_code<Derived,true>(system_error2::status_code<Derived> &&) noexcept' being compiled
[build]         with
[build]         [
[build]             Derived=BasicStringStatusCodeDomain<15524508317838324489>
[build]         ]

[Niall Douglas]

This is definitely a bug in status code, not outcome, so transferring. quickcpplib has an implementation of this exact code sequence which preferentially chooses std::bit_cast when it is available, so that ought to be transplanted into here.

Thanks for the BR, and my apologies for not doing this work sooner (I forgot!)

[Niall Douglas]

Ok, give that commit a try there and see how it goes for you.

[Dennis]

Yes that seems to work. Thank you

[Niall Douglas]

Thanks for the confirm and BR!