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

[Martin Storsjö]

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.

// Martin