On Fri, Feb 7, 2014 at 12:59 PM, Misty De Meo <mistyde...@gmail.com> wrote: > On Fri, Feb 7, 2014 at 11:09 AM, Ian Lance Taylor <i...@google.com> wrote: >> On Fri, Feb 7, 2014 at 9:06 AM, Misty De Meo <mistyde...@gmail.com> wrote: >>> Revision 192853 added a new test for availability of _Unwind_GetIPInfo >>> in the system unwinder to the configure script of libbacktrace: >>> http://repo.or.cz/w/official-gcc.git/commitdiff/a4a5a77adfc9c28d6963e5ae054c997d57cfc7fa >>> It was apparently added to fix a bug building with GCC 4.0 on Mac OS X >>> 10.5. >>> >>> This is one of a few checks for that function (there's also one in the >>> top-level configure script). Unfortunately, while the other tests have >>> special handling for Mac OS X 10.4, this new test does not take it >>> into account. >>> >>> In 10.4, _Unwind_GetIPInfo is not exported in the system unwinder. >>> Trying to build a test program will succeed, but will fail to link due >>> to the symbol being undefined. The test added to libbacktrace's >>> configure used AC_COMPILE_IFELSE, which meant it didn't try to link >>> and erroneously flagged _Unwind_GetIPInfo as usable. This led to build >>> errors when linking. >>> >>> This small patch changes configure to use AC_LINK_IFELSE, which fixes >>> the issue on OS X 10.4. I've been able to build GCC successfully. >>> >>> GCC 4.8 and 4.9 are affected by this issue. >>> >>> A bug report is filed for this as #58710 >>> (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58710). >>> >>> diff --git libbacktrace/configure.ac libbacktrace/configure.ac >>> index 28b2a1c..e0e0e08 100644 >>> --- libbacktrace/configure.ac >>> +++ libbacktrace/configure.ac >>> @@ -144,7 +144,7 @@ else >>> ac_save_CFFLAGS="$CFLAGS" >>> CFLAGS="$CFLAGS -Werror-implicit-function- >>> declaration" >>> AC_MSG_CHECKING([for _Unwind_GetIPInfo]) >>> - AC_COMPILE_IFELSE( >>> + AC_LINK_IFELSE( >>> [AC_LANG_PROGRAM( >>> [#include "unwind.h" >>> struct _Unwind_Context *context; >> >> >> This is OK with a ChangeLog entry for 4.8 branch and mainline. > > Thanks. Is this sufficient? > > 2014-02-07 Misty De Meo <mi...@brew.sh> > > target/PR58710 > * configure.ac: Use AC_LINK_IFELSE in check for _Unwind_GetIPInfo. > * configure: Regenerate.
Thanks. Committed to mainline and 4.8 branch. Ian
