])
-dnl Usage: LYX_CXX_CXX11_FLAGS: add to AM_CXXFLAGS the best flag that
-selects C++11 mode; gives an error when C++11 mode is not found.
+dnl Usage: LYX_CXX_CXX11_FLAGS(VERSION): add to AM_CXXFLAGS the best flag that
+dnl selects C++11 mode; gives an error when C++11 mode is not found.
+dnl VERSION is a list of years to try (e.g. 11 or {14,11}).
AC_DEFUN([LYX_CXX_CXX11_FLAGS],
-[AC_CACHE_CHECK([for at least C++11 mode], [lyx_cv_cxx11_flags],
+[AC_CACHE_CHECK([for a good C++ mode], [lyx_cv_cxx11_flags],
[lyx_cv_cxx11_flags=none
- for flag in -std=c++14 -std=c++11 "" -std=gnu++14 -std=gnu++11 ; do
+ for flag in `eval echo -std=c++$1 default -std=gnu++$1` ; do
+ if test $flag = default ; then
+ flag=
+ fi
save_CPPFLAGS=$CPPFLAGS
CPPFLAGS="$AM_CPPFLAGS $CPPFLAGS"
save_CXXFLAGS=$CXXFLAGS
CXXFLAGS=$save_CXXFLAGS
CPPFLAGS=$save_CPPFLAGS
done])
- if test $lyx_cv_cxx11_flags = none ; then
- AC_MSG_ERROR([Cannot find suitable C++11 mode for compiler $CXX])
+ if test x$lyx_cv_cxx11_flags = xnone ; then
+ AC_MSG_ERROR([Cannot find suitable mode for compiler $CXX])
fi
AM_CXXFLAGS="$lyx_cv_cxx11_flags $AM_CXXFLAGS"
])
[AC_REQUIRE([AC_PROG_CXX])
AC_REQUIRE([AC_PROG_CXXCPP])
+### We might want to force the C++ standard.
+AC_ARG_ENABLE(cxx-mode,
+ AS_HELP_STRING([--enable-cxx-mode],[choose C++ standard (default: 14, then 11)]),,
+ [enable_cxx_mode={14,11}]
+)
+
AC_LANG_PUSH(C++)
LYX_PROG_CLANG
-LYX_CXX_CXX11_FLAGS
+LYX_CXX_CXX11_FLAGS($enable_cxx_mode)
LYX_LIB_STDCXX
LYX_LIB_STDCXX_CXX11_ABI
LYX_CXX_USE_REGEX