Checked iterator warnings when building with MSVC 2015

[deleoDev91]

Hi, I'm using spdlog which uses your library. I tried to update the spdlog version but my project failed to build because fmt dont use stdext checked iterartor utilities at std copy calls in include\fmt\format.h(3016). Compiler says that it can be avoided if I desable certain warnings, but I dont want to do this unless its strictly neccessary. For now I solved it downloading and older version of fmt but It would be nice to dont have to depend from an older version to avoid compatibility problems. Thanks for the help.

[vitaut]

Are you referring to MSVC 2015 by msvc14? What errors do you get?

The current master compiles fine on 2015: https://ci.appveyor.com/project/vitaut/fmt/builds/35876519.

[deleoDev91]

By MSVC 14 I refer myself to VS2015, if its that what are you asking(v140). It gives me problem at std:copy_n. It says that its copying a memory using unchecked limits in iterators. Actually, this isnt a bug but msvc doesnt like using std copy without using aditional stuff from stdext. I had this problem in a case when i was trying copy data from a buffer to a different destination using only pointers. Once I used stdext::checked_array_iterator the error disappear.

By the way, I checked the build you posted and it gives the same messages (and the same problem with std copy), the only difference is that mine fails at the end. Maybe the problem is some configuration values in my project

[vitaut]

One repro from #2092:

#include <fmt/core.h>

int main() {
  fmt::format(L"{}_{:04d}-{:02d}-{:02d}{}", L"filename", 2020, 1, 12, L".txt"};
}

[Othereum]

Still not fixed

c:\program files (x86)\microsoft visual studio 14.0\vc\include\xutility(2372): error C4996: 'std::copy::_Unchecked_iterators::_Deprecate': Call to 'std::copy' with parameters that may be unsafe - this call relies on the caller to check that the passed values are correct. To disable this warning, use -D_SCL_SECURE_NO_WARNINGS. See documentation on how to use Visual C++ 'Checked Iterators'
  fmt\include\fmt\chrono.h(449): note: '_OutIt std::copy<T*,fmt::v7::detail::buffer_appender<T>>(_InIt,_InIt,_OutIt)'
          with
          [
              _OutIt=fmt::v7::detail::buffer_appender<char>,
              T=char,
              _InIt=char *
          ]

fmt/include/fmt/chrono.h

Line 451 in e718ec3

return std::copy(buf.begin(), buf.end(), ctx.out());

Compiled with /W4 /sdl /WX- in debug configuration

[tsilia]

Hello.

I'm also using VS2015 update3 (toolset v140) and getting two compiler errors C4996:

c:\program files (x86)\microsoft visual studio 14.0\vc\include\xmemory(102): error C4996: 'std::uninitialized_copy::_Unchecked_iterators::_Deprecate': Call to 'std::uninitialized_copy' with parameters that may be unsafe - this call relies on the caller to check that the passed values are correct. To disable this warning, use -D_SCL_SECURE_NO_WARNINGS. See documentation on how to use Visual C++ 'Checked Iterators'
  c:\program files (x86)\microsoft visual studio 14.0\vc\include\xmemory(102): note: see declaration of 'std::uninitialized_copy::_Unchecked_iterators::_Deprecate'
  fmt\format.h(501): note: see reference to function template instantiation '_FwdIt std::uninitialized_copy<InputIt,OutChar*>(_InIt,_InIt,_FwdIt)' being compiled
          with
          [
              _FwdIt=char *,
              InputIt=const char *,
              OutChar=char,
              _InIt=const char *
          ]

and

c:\program files (x86)\microsoft visual studio 14.0\vc\include\xutility(2372): error C4996: 'std::copy::_Unchecked_iterators::_Deprecate': Call to 'std::copy' with parameters that may be unsafe - this call relies on the caller to check that the passed values are correct. To disable this warning, use -D_SCL_SECURE_NO_WARNINGS. See documentation on how to use Visual C++ 'Checked Iterators'
  c:\program files (x86)\microsoft visual studio 14.0\vc\include\xutility(2372): note: see declaration of 'std::copy::_Unchecked_iterators::_Deprecate'
  fmt\chrono.h(455): note: see reference to function template instantiation '_OutIt std::copy<T*,fmt::v7::detail::buffer_appender<T>>(_InIt,_InIt,_OutIt)' being compiled
          with
          [
              _OutIt=fmt::v7::detail::buffer_appender<char>,
              T=char,
              _InIt=char *
          ]

Here's the minimal example to reproduces the issue (taken from https://fmt.dev/latest/api.html#chrono-api):

#include <fmt/chrono.h>

const std::time_t t = std::time(nullptr);
fmt::print("{:%Y-%m-%d}", fmt::localtime(t));

[vitaut]

Suppressed the warnings in ab7c33e.

[tsilia]

Good job, it's now working with SDL checks on.
Thank you!

[deleoDev91]

Downloaded, compiled, tested and everything works ok. Good job and thank you