Introduce `FMT_BEGIN_DETAIL_NAMESPACE` and `FMT_END_DETAIL_NAMESPACE` for `namespace detail` sections embedded in that part of the code that contains all declarations that are exported from the module, i.e. which is enclosed by `FMT_MODULE_EXPORT_BEGIN` and `FMT_MODULE_EXPORT_END`. Given a correct implementation of C++20 modules, neither the name `fmt::detail` nor any of its contents will become visible outside of the module.
* add FMT_INSTANTIATION_DEF_API for msvc
This should fix https://github.com/fmtlib/fmt/issues/2228
To fix difference dllexport requirements
msvc: dllexport at template instantiation definition in format.cc
clang: dllexport at template instantiation declaration (extern template) in format.h
If the ``_POSIX_`` flag is set, _fdopen will not be defined by
Mingw headers, which is addressed by this commit.
For what is worth, as opposed to ``fdopen``, ``_pipe`` *will*
actually have the ``_`` prefix when ``_POSIX_`` is set.
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
* Update format.cc
As the explicit instantiation *declaration* of `internal::basic_data<void>` in format.h, this explicit instantiation *definition* should mirror FMT_API also.
* Mirror visibility of explicit instantiation declaration
explicit instantiation declaration of internal::basic_data<void> should mirror visibility of FMT_API
* Eliminate `__declspec(dllexport)` designation on extern template internal::basic_data<> when `extern` affected during exporting phase.
* Add `FMT_EXTERN_TEMPLATE_API` for designate DLL export `extern template`
When exporting DLL, do not designate `__declspec(dllexport)` any template that has any explicit class template declaration a.k.a. `extern template`. Instead, designate `__declspec(dllexport)` at single point where we have explicit class template definition a.k.a. normal instantiation without `extern`
Note: this is a c++11 feature.
* Delete whole `FMT_USE_EXTERN_TEMPLATES` block and its condition
1. Remove whole `FMT_USE_EXTERN_TEMPLATES` block
(trailing `FMT_UDL_TEMPLATE` block)
````
#ifndef FMT_USE_EXTERN_TEMPLATES
# ifndef FMT_HEADER_ONLY
# define FMT_USE_EXTERN_TEMPLATES \
((FMT_CLANG_VERSION >= 209 && __cplusplus >= 201103L) || \
(FMT_GCC_VERSION >= 303 && FMT_HAS_GXX_CXX11))
# else
# define FMT_USE_EXTERN_TEMPLATES 0
# endif
#endif
````
2. Delete `FMT_USE_EXTERN_TEMPLATES` condition, only condition, that trailing basic_data class template definition.
````
#if FMT_USE_EXTERN_TEMPLATES
extern template struct basic_data<void>;
#endif
````
3. Replace `FMT_API` with new `FMT_EXTERN_TEMPLATE_API` added in `core.h` for sake of extern template of `basic_data<void>`
* Add `#define FMT_EXTERN extern` only when not `FMT_HEADER_ONLY`
* Replace `extern` on basic_data<void> with the `FMT_EXTERN` condition in core.h
* replace misspelled if !define() with ifndef
