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.
