[llvm] r199313 - Add a check to configure that the libstdc++ selected by Clang isn't
Bob Wilson
bob.wilson at apple.com
Wed Jan 15 10:20:20 PST 2014
Our buildbots have an old version of libstdc++ that has that problem. But, we run configure with -stdlib=libc++, so it doesn’t matter what version of libstdc++ is on the machine.
The configure check is not honoring —enable-libcpp, so it’s checking the wrong library.
On Jan 15, 2014, at 10:17 AM, Chandler Carruth <chandlerc at gmail.com> wrote:
> On Wed, Jan 15, 2014 at 10:13 AM, Bob Wilson <bob.wilson at apple.com> wrote:
> We shouldn’t be checking this when configure is run with —enable-libcpp. This is breaking all of our buildbots.
>
> Why?
>
> Notably, is there some version of libc++ which *also* has the bug that libstdc++ has?
>
>
> On Jan 15, 2014, at 2:31 AM, Chandler Carruth <chandlerc at gmail.com> wrote:
>
> > 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
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>
>
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