[vlc-devel] [PATCH] configure: Check if C++ headers define locale_t

[Martin Storsjö]

On Wed, 28 Feb 2018, Martin Storsjö wrote:

> On Wed, 28 Feb 2018, Martin Storsjö wrote:
>
>> In environments that lack a full locale.h implementation, the C++
>> headers might implement some fallbacks with the same name
>> (on windows, libcxx does this).
>> 
>> In these cases, don't provide the normal fallbacks from vlc_fixups.h
>> when compiling in C++ mode, but include the C++ <locale> header instead.
>> 
>> If <locale> provides locale_t, include the header and define
>> HAVE_NEWLOCALE (which skips the vlc_fixups.h version of locale_t),
>> but keep the vlc_fixups.h fallback for uselocale. (One could
>> also add another configure test for whether <locale> provides
>> the uselocale function.)
>> 
>> (libcxx doesn't provide any fallback for the uselocale function
>> since it isn't easily implemented with the msvcrt _locale_t objects.
>> The libcxx fallback locale_t objects are applied via the setlocale
>> function, and passed to functions that take a _locale_t parameter.)
>> ---
>> configure.ac         | 12 ++++++++++++
>> include/vlc_fixups.h |  5 +++++
>> 2 files changed, 17 insertions(+)
>> 
>> diff --git a/configure.ac b/configure.ac
>> index c03533e..0faeef9 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -854,6 +854,18 @@ AC_CHECK_HEADERS([features.h getopt.h linux/dccp.h 
>> linux/magic.h mntent.h sys/ev
>> dnl  MacOS
>> AC_CHECK_HEADERS([xlocale.h])
>> 
>> +dnl Check if C++ headers define locale_t
>> +AC_LANG_PUSH(C++)
>> +AC_CACHE_CHECK([if C++ headers define locale_t],
>> +  [ac_cv_cxx_locale_t],
>> +  [ac_cv_cxx_locale_t=no
>> +   AC_TRY_COMPILE([#include <locale>], [locale_t loc;],
>> +                    [ac_cv_cxx_locale_t=yes])])
>> +if test "${ac_cv_cxx_locale_t}" != "no"; then
>> +  AC_DEFINE(HAVE_CXX_LOCALE_T, 1, Define to 1 if C++ headers define 
>> locale_t)
>> +fi
>> +AC_LANG_POP(C++)
>> +
>> dnl LP64 and LLP64 architectures had better define ssize_t by themselves...
>> AH_TEMPLATE(ssize_t, [Define to `int' if <stddef.h> does not define.]) dnl 
>> ` (fix VIM syntax highlight
>> AC_CHECK_TYPE(ssize_t,, [
>> diff --git a/include/vlc_fixups.h b/include/vlc_fixups.h
>> index 0bd8442..533cff1 100644
>> --- a/include/vlc_fixups.h
>> +++ b/include/vlc_fixups.h
>> @@ -314,6 +314,11 @@ void *aligned_alloc(size_t, size_t);
>> # define HAVE_USELOCALE
>> #endif
>> 
>> +#if !defined(HAVE_USELOCALE) && defined(HAVE_CXX_LOCALE_T) && 
>> defined(__cplusplus)
>> +# include <locale>
>> +# define HAVE_NEWLOCALE
>
> Locally amended the check above to check !defined(HAVE_NEWLOCALE) instead, 
> for consistency.

And pushed. Now the current git master should be buildable with llvm-mingw 
for i686 and x86_64 without any out-of-tree patches.

// Martin