[llvm] r199313 - Add a check to configure that the libstdc++ selected by Clang isn't
Chandler Carruth
chandlerc at gmail.com
Wed Jan 15 10:25:43 PST 2014
On Wed, Jan 15, 2014 at 10:20 AM, Bob Wilson <bob.wilson at apple.com> wrote:
> 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.
>
Ahh, I see, it's because the enabling of libc++ happens too late. I had
expected that when the host was clang on darwin it would *default* to
libc++, sorry for that.
Lemme try re-shuffling these tests to better cope with that.
>
>
> 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
>>
>>
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>
>
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20140115/47f6c663/attachment.html>
More information about the llvm-commits
mailing list