D:\a\fmt\fmt\test\compile-test.cc(362,3): fatal error C1001: Internal compiler error. [D:\a\fmt\build\test\compile-test.vcxproj]
(compiler file 'D:\a\_work\1\s\src\vctools\Compiler\CxxFE\sl\p1\c\constexpr\constexpr.cpp', line 8635)
Signed-off-by: Vladislav Shchapov <vladislav@shchapov.ru>

Signed-off-by: Vladislav Shchapov <vladislav@shchapov.ru>

Signed-off-by: Vladislav Shchapov <vladislav@shchapov.ru>

* #2954: Provide std::conjunction and std::disjunction substitutes

* #2954: Use conjunction and disjunction substitute to make formatter specializations for ranges and maps more robust (especially for Visual Studio compiler family)

* #2954: As workaround for older MSVC compilers split formatter<std::filesystem::path> partial template specialization into two explicit specialization.

* 2954: Add test case

* Provide simplified implementations of conjunction and disjunction

* Remove workaround explicit specializations if the partial specialization would cause an ambiguity error

* Eliminate extra-test and merge it into existing std-test instead. Add conditionals for filesystem::path testing that does not run into the ambiguity problem.

Signed-off-by: Vladislav Shchapov <vladislav@shchapov.ru>

Signed-off-by: Vladislav Shchapov <vladislav@shchapov.ru>

Add support for 'std::variant' in C++17.

For C++17, if all the alternatives of a variant are formattable
the variant is now also formattable. In addition 'std::monostate'
is now formattable.

Moves implementation into 'std.h', and tests into 'std-test.cc'.

Avoid fold-expression since MSVC was crashing.

Add section for 'fmt/std.h' in API-docs.

Signed-off-by: Vladislav Shchapov <vladislav@shchapov.ru>

This enables the use of FMT_ENFORCE_COMPILE_STRING on MSVC 2019.