[llvm] r199313 - Add a check to configure that the libstdc++ selected by Clang isn't
Chandler Carruth
chandlerc at gmail.com
Wed Jan 15 02:31:16 PST 2014
Author: chandlerc
Date: Wed Jan 15 04:31:15 2014
New Revision: 199313
URL: http://llvm.org/viewvc/llvm-project?rev=199313&view=rev
Log:
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).
Modified:
llvm/trunk/autoconf/configure.ac
llvm/trunk/configure
Modified: llvm/trunk/autoconf/configure.ac
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/autoconf/configure.ac?rev=199313&r1=199312&r2=199313&view=diff
==============================================================================
--- llvm/trunk/autoconf/configure.ac (original)
+++ llvm/trunk/autoconf/configure.ac Wed Jan 15 04:31:15 2014
@@ -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 <atomic>
+std::atomic<float> 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
Modified: llvm/trunk/configure
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/configure?rev=199313&r1=199312&r2=199313&view=diff
==============================================================================
--- llvm/trunk/configure (original)
+++ llvm/trunk/configure Wed Jan 15 04:31:15 2014
@@ -3593,16 +3593,9 @@ cat confdefs.h >>conftest.$ac_ext
cat >>conftest.$ac_ext <<_ACEOF
/* end confdefs.h. */
#if ! __clang__
- #error
- #endif
+ #error
+ #endif
-int
-main ()
-{
-
- ;
- return 0;
-}
_ACEOF
rm -f conftest.$ac_objext
if { (ac_try="$ac_compile"
@@ -3650,16 +3643,9 @@ cat confdefs.h >>conftest.$ac_ext
cat >>conftest.$ac_ext <<_ACEOF
/* end confdefs.h. */
#if ! __GNUC__
- #error
- #endif
-
-int
-main ()
-{
+ #error
+ #endif
- ;
- return 0;
-}
_ACEOF
rm -f conftest.$ac_objext
if { (ac_try="$ac_compile"
@@ -3748,13 +3734,6 @@ cat >>conftest.$ac_ext <<_ACEOF
#error This version of Clang is too old to build LLVM
#endif
-int
-main ()
-{
-
- ;
- return 0;
-}
_ACEOF
rm -f conftest.$ac_objext
if { (ac_try="$ac_compile"
@@ -3810,6 +3789,88 @@ bypass these sanity checks." >&2;}
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+ { echo "$as_me:$LINENO: checking whether Clang will select a modern C++ standard library" >&5
+echo $ECHO_N "checking whether Clang will select a modern C++ standard library... $ECHO_C" >&6; }
+ llvm_cv_old_cxxflags="$CXXFLAGS"
+ CXXFLAGS="$CXXFLAGS -std=c++0x"
+ cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h. */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h. */
+
+#include <atomic>
+std::atomic<float> x(0.0f);
+int main() { return (float)x; }
+
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+if { (ac_try="$ac_link"
+case "(($ac_try" in
+ *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+ *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+ (eval "$ac_link") 2>conftest.er1
+ ac_status=$?
+ grep -v '^ *+' conftest.er1 >conftest.err
+ rm -f conftest.er1
+ cat conftest.err >&5
+ echo "$as_me:$LINENO: \$? = $ac_status" >&5
+ (exit $ac_status); } &&
+ { ac_try='test -z "$ac_cxx_werror_flag" || test ! -s conftest.err'
+ { (case "(($ac_try" in
+ *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+ *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+ (eval "$ac_try") 2>&5
+ ac_status=$?
+ echo "$as_me:$LINENO: \$? = $ac_status" >&5
+ (exit $ac_status); }; } &&
+ { ac_try='test -s conftest$ac_exeext'
+ { (case "(($ac_try" in
+ *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+ *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+ (eval "$ac_try") 2>&5
+ ac_status=$?
+ echo "$as_me:$LINENO: \$? = $ac_status" >&5
+ (exit $ac_status); }; }; then
+ { echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+else
+ echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ { echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+ { { echo "$as_me:$LINENO: error:
+We detected a missing feature in the standard C++ library that was known to be
+missing in libstdc++4.6 and implemented in libstdc++4.7. There are numerous
+C++11 problems with 4.6's library, and we don't support GCCs or libstdc++ older
+than 4.7. You will need to update your system and ensure Clang uses the newer
+standard library.
+
+If this error is incorrect or you need to force things to work, you may pass
+'--disable-compiler-version-checks' to configure to bypass this test." >&5
+echo "$as_me: 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." >&2;}
+ { (exit 1); exit 1; }; }
+fi
+
+rm -f core conftest.err conftest.$ac_objext \
+ conftest$ac_exeext conftest.$ac_ext
;;
gcc)
{ echo "$as_me:$LINENO: checking whether GCC is new enough" >&5
@@ -3825,13 +3886,6 @@ cat >>conftest.$ac_ext <<_ACEOF
#error This version of GCC is too old to build LLVM
#endif
-int
-main ()
-{
-
- ;
- return 0;
-}
_ACEOF
rm -f conftest.$ac_objext
if { (ac_try="$ac_compile"
@@ -10606,7 +10660,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<EOF
-#line 10609 "configure"
+#line 10663 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
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