From 9c62b5eabb41d41023815df01d07bda5abbd8c4c Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Wed, 15 Jan 2014 10:31:15 +0000 Subject: Add a check to configure that the libstdc++ selected by Clang isn't libstdc++v4.6. This is quite hard to test directly, so we test for it by checking a known missing feature in that version that was added in v4.7. This should prevent users from upgrading Clang but not GCC and hosting with a too-old GCC's libstdc++ and getting strange and hard to debug errors when we switch to C++11 by default. Also, switch several of the macros I introduced to use AC_LANG_SOURCE rather than AC_LANG_PROGRAM as we don't need configure's help writing our main function (and we don't need such a function at all for most of the tests). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199313 91177308-0d34-0410-b5e6-96231b3b80d8 --- autoconf/configure.ac | 44 ++++++++++++++++++++++++++++++++++---------- 1 file changed, 34 insertions(+), 10 deletions(-) (limited to 'autoconf') diff --git a/autoconf/configure.ac b/autoconf/configure.ac index 0a90de86e1..6906a7586b 100644 --- a/autoconf/configure.ac +++ b/autoconf/configure.ac @@ -102,15 +102,15 @@ dnl other possible compilers. AC_MSG_CHECKING([whether GCC or Clang is our host compiler]) AC_LANG_PUSH([C++]) llvm_cv_cxx_compiler=unknown -AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#if ! __clang__ - #error - #endif - ]])], +AC_COMPILE_IFELSE([AC_LANG_SOURCE([[#if ! __clang__ + #error + #endif + ]])], llvm_cv_cxx_compiler=clang, - [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#if ! __GNUC__ - #error - #endif - ]])], + [AC_COMPILE_IFELSE([AC_LANG_SOURCE([[#if ! __GNUC__ + #error + #endif + ]])], llvm_cv_cxx_compiler=gcc, [])]) AC_LANG_POP([C++]) AC_MSG_RESULT([${llvm_cv_cxx_compiler}]) @@ -129,7 +129,7 @@ case "$enableval" in case "$llvm_cv_cxx_compiler" in clang) AC_MSG_CHECKING([whether Clang is new enough]) - AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ + AC_COMPILE_IFELSE([AC_LANG_SOURCE([[ #if __clang_major__ < 3 || (__clang_major__ == 3 && __clang_minor__ < 1) #error This version of Clang is too old to build LLVM #endif @@ -140,10 +140,34 @@ case "$enableval" in The selected Clang compiler is not new enough to build LLVM. Please upgrade to Clang 3.1. You may pass --disable-compiler-version-checks to configure to bypass these sanity checks.])]) + + dnl Note that libstdc++4.6 is known broken for C++11 builds. The errors + dnl are sometimes deeply confusing though. Here we test for an obvious + dnl incomplete feature in 4.6's standard library that was completed in + dnl 4.7's. + AC_MSG_CHECKING([whether Clang will select a modern C++ standard library]) + llvm_cv_old_cxxflags="$CXXFLAGS" + CXXFLAGS="$CXXFLAGS -std=c++0x" + AC_LINK_IFELSE([AC_LANG_SOURCE([[ +#include +std::atomic x(0.0f); +int main() { return (float)x; } +]])], + [AC_MSG_RESULT([yes])], + [AC_MSG_RESULT([no]) + AC_MSG_ERROR([ +We detected a missing feature in the standard C++ library that was known to be +missing in libstdc++4.6 and implemented in libstdc++4.7. There are numerous +C++11 problems with 4.6's library, and we don't support GCCs or libstdc++ older +than 4.7. You will need to update your system and ensure Clang uses the newer +standard library. + +If this error is incorrect or you need to force things to work, you may pass +'--disable-compiler-version-checks' to configure to bypass this test.])]) ;; gcc) AC_MSG_CHECKING([whether GCC is new enough]) - AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ + AC_COMPILE_IFELSE([AC_LANG_SOURCE([[ #if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7) #error This version of GCC is too old to build LLVM #endif -- cgit v1.2.3