diff options
-rw-r--r-- | configure.ac | 78 |
1 files changed, 32 insertions, 46 deletions
diff --git a/configure.ac b/configure.ac index a0e38999258c..cbc8f2c0a8fd 100644 --- a/configure.ac +++ b/configure.ac @@ -6061,6 +6061,36 @@ elif test "$GCC" = "yes" -o "$COM_IS_CLANG" = TRUE; then CXXFLAGS="$CXXFLAGS -DSYSTEM_LIBCMIS $LIBCMIS_CFLAGS" fi AC_LANG_PUSH([C++]) + dnl Clang 3.9 supports __float128 since + dnl <http://llvm.org/viewvc/llvm-project?view=revision&revision=268898> "Enable support for + dnl __float128 in Clang and enable it on pertinent platforms", but Clang 3.8 may need a + dnl hacky workaround to be able to include <vector> (as is done in the main check whether + dnl $flag is supported below, so check this first): + my_float128hack= + my_float128hack_impl=-D__float128=void + AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ + #include <vector> + // some Clang fail when compiling against libstdc++ headers with -std=gnu++0x + // (__float128) + ]]) + ],,[ + dnl The only reason why libstdc++ headers fail with Clang in C++11 mode is because they + dnl use the __float128 type that Clang doesn't know (libstdc++ checks whether __float128 + dnl is available during its build, but it's usually built using GCC, and so c++config.h + dnl hardcodes __float128 being supported). At least for some older libstc++, the only + dnl place where __float128 is used is in a template specialization, -D__float128=void + dnl will avoid the problem there while still causing a problem if somebody actually uses + dnl the type. (But some later libstdc++ are known to use __float128 also in algorithm -> + dnl bits/stl_alog.h -> cstdlib -> bits/std_abs.h, in a way that unfortunately cannot be + dnl "fixed" with this hack): + CXXFLAGS="$CXXFLAGS $my_float128hack_impl" + AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ + #include <vector> + // some Clang fail when compiling against libstdc++ headers with -std=gnu++0x + // (__float128) + ]]) + ],[my_float128hack=$my_float128hack_impl]) + ]) AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ #include <algorithm> #include <functional> @@ -6091,7 +6121,7 @@ elif test "$GCC" = "yes" -o "$COM_IS_CLANG" = TRUE; then void f(std::vector<int> & v, std::function<bool(int, int)> fn) { std::sort(v.begin(), v.end(), fn); } - ]])],[CXXFLAGS_CXX11=$flag]) + ]])],[CXXFLAGS_CXX11=$flag $my_float128hack]) AC_LANG_POP([C++]) CXXFLAGS=$save_CXXFLAGS if test -n "$CXXFLAGS_CXX11"; then @@ -6106,6 +6136,7 @@ elif test "$GCC" = "yes" -o "$COM_IS_CLANG" = TRUE; then AC_MSG_ERROR(no) fi fi +AC_SUBST(CXXFLAGS_CXX11) dnl Test for temporarily incompatible libstdc++ 4.7.{0,1}, where dnl <https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=179528> introduced @@ -6167,51 +6198,6 @@ return !(i != 0 && j != 0); AC_LANG_POP([C++]) CXXFLAGS=$save_CXXFLAGS -dnl Clang 3.9 supports __float128 since -dnl <http://llvm.org/viewvc/llvm-project?view=revision&revision=268898> "Enable support for -dnl __float128 in Clang and enable it on pertinent platforms": -AC_MSG_CHECKING([whether $CXX supports C++11 without __float128 compile error]) -save_CXXFLAGS=$CXXFLAGS -CXXFLAGS="$CXXFLAGS $CXXFLAGS_CXX11" -AC_LANG_PUSH([C++]) - -AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ -#include <vector> - // some Clang fail when compiling against libstdc++ headers with -std=gnu++0x - // (__float128) -]]) - ],[ AC_MSG_RESULT(yes) ], - [ - AC_MSG_RESULT(no) - # The only reason why libstdc++ headers fail with Clang in C++11 mode is because - # they use the __float128 type that Clang doesn't know (libstdc++ checks whether - # __float128 is available during its build, but it's usually built using GCC, - # and so c++config.h hardcodes __float128 being supported). As the only place - # where __float128 is actually used is in a template specialization, - # -D__float128=void will avoid the problem there while still causing a problem - # if somebody actually uses the type. - AC_MSG_CHECKING([whether -D__float128=void workaround helps]) - CXXFLAGS="$CXXFLAGS -D__float128=void" - AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ -#include <vector> - // some Clang fail when compiling against libstdc++ headers with -std=gnu++0x - // (__float128) -]]) - ], - [ - AC_MSG_RESULT(yes) - CXXFLAGS_CXX11="$CXXFLAGS_CXX11 -D__float128=void" - ], - [ - AC_MSG_ERROR(no) - ]) -]) - -AC_LANG_POP([C++]) -CXXFLAGS=$save_CXXFLAGS - -AC_SUBST(CXXFLAGS_CXX11) - AC_MSG_CHECKING([whether $CXX supports C++14 constexpr]) save_CXXFLAGS=$CXXFLAGS CXXFLAGS="$CXXFLAGS $CXXFLAGS_CXX11" |