Make it possible to select C++ standard with autoconf

Introduce new configure option --enable-cxx-mode=MODE, which allows to
force a C++ version. The default is {14,11}, which means that C++14 is
chosen if it is supported, and C++11 will be selected as a fallback.

Using --enable-cxx-mode=11 ensures that LyX compiles correctly
with an older C++11 compiler.
This commit is contained in:
Jean-Marc Lasgouttes 2020-11-02 17:40:29 +01:00
parent 060c3de2f0
commit ce526607ff
2 changed files with 20 additions and 6 deletions

View File

@ -208,6 +208,10 @@ The following options allow you to tweak the generated code more
precisely (see the description of --enable-build-type for the default
values):
o --enable-cxx-mode=VALUE can be used to select a C++ standard, for
example --enable-cxx-mode=11. The default is to try C++14, and then
C++11.
o --enable-optimization=VALUE enables you to set optimization to a
higher level than the default, for example --enable-optimization=-O3.

View File

@ -165,11 +165,15 @@ fi
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 selects C++11 mode; gives an error when C++11 mode is not found.
dnl Parameter 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
@ -202,8 +206,8 @@ AC_DEFUN([LYX_CXX_CXX11_FLAGS],
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 $AM_CXXFLAGS"
])
@ -304,9 +308,15 @@ AC_DEFUN([LYX_PROG_CXX],
[AC_REQUIRE([AC_PROG_CXX])
AC_REQUIRE([AC_PROG_CXXCPP])
### We might want to disable debug
AC_ARG_ENABLE(cxx-mode,
AS_HELP_STRING([--enable-cxx-mode],[choose C++ standard (default: 14, then 11)]),,
[enable_cxx_mode=14,11]
)
AC_LANG_PUSH(C++)
LYX_PROG_CLANG
LYX_CXX_CXX11_FLAGS
LYX_CXX_CXX11_FLAGS($enable_cxx_mode)
LYX_LIB_STDCXX
LYX_LIB_STDCXX_CXX11_ABI
LYX_CXX_USE_REGEX