* Allow disabling floating point support
Add FMT_USE_FLOAT, FMT_USE_DOUBLE and FMT_USE_LONG_DOUBLE to allow a
user of the library to configure the float types they want to allow.
This is specially useful in embedded environements where code size is
important.
* Avoid conditional macros to disable float support
* Add is_supported_floating_point constexpr function
* Fix empty-body warning
FMT_DEPRECATED is now defined as FMT_HAS_CPP14_ATTRIBUTE(deprecated), as this attribute was introduced in C++14.
FMT_FALLTHROUGH is now defined as FMT_HAS_CPP17_ATTRIBUTE(fallthrough), as this attribute was introduced in C++17.
FMT_MAYBE_UNUSED is defined as FMT_HAS_CPP17_ATTRIBUTE(maybe_unused), as this attribute was introduced in C++17.
FMT_MAYBE_UNUSED has been applied to fix a couple of -Wunused-member-function warnings from clang.
Make FMT_API symbols use the default visibility on non-Windows
platforms. Otherwise, one cannot use the generated fmt library when
compiling globally with -fvisibility=hidden.
Fixes compile errors like:
```
../3rdParty/fmt/include/fmt/core.h:757: error: undefined reference to 'fmt::v6::internal::assert_fail(char const*, int, char const*)'
```
Note that the symbol exists, but is local:
```
$ nm -C libfmtd.so.6.1.3 | grep assert_fail
U __assert_fail
0000000000233ffa t fmt::v6::internal::assert_fail(char const*, int, char const*)
```
With this patch, the compile error is gone and the symbol is properly
exported:
```
$ nm -a bin/libfmtd.so -C | grep assert_fail
U __assert_fail
00000000002366ba T fmt::v6::internal::assert_fail(char const*, int, char const*)
```
Change-Id: I96054e622d9a2ae81907e1b01a1033e629767a91
## Problem
In the case of an existing `fmt` namespace (in my project this looks like `Project::fmt`) it is possible to get a namespace clash in debug builds (MSVC 2017)
## Proposed Solution
When referencing `fmt` internally, be explicit that it is relative to the global namespace using `::fmt`
The nvcc compiler (at least up to 9.2) defines `__SIZEOF_INT128__`, but doesn't support 128-bit integers on device code:
```
error: "fmt::v6::format_arg_store<fmt::v6::basic_format_context<std::back_insert_iterator<fmt::v6::internal::buffer<char>>, char>, const char *, int, const char *>" contains a 128-bit integer, which is not supported in device code
```
The `std::is_base_of<T,U>()` and `std::is_reference<T>()` member functions were added in C++14. To maintain C++11 compatibility, use the `::value` instead.
Current code fails on intel-17 and other compilers if using strict C++11
