[Patch] Fix configure test for __libc_stack_end

[Patch] Fix configure test for __libc_stack_end

[Matthias Koeppe]

The test for `guile_cv_have_libc_stack_end' does not work reliably
because the compiler can optimize away the use of the variable in the
test program.  This happened to me on Solaris with the Sun Forte C
compiler.

Here is a patch.

--- configure.in.~1.220.~	Mon Jun 16 16:49:24 2003
+++ configure.in	Wed Jun 18 10:49:17 2003
@@ -603,8 +603,9 @@
 
 AC_MSG_CHECKING(for __libc_stack_end)
 AC_CACHE_VAL(guile_cv_have_libc_stack_end,
-[AC_TRY_LINK([extern char *__libc_stack_end;],
-             [char *p = __libc_stack_end;],
+[AC_TRY_LINK([#include <stdio.h>
+extern char *__libc_stack_end;],
+             [printf("%s", (char*) __libc_stack_end);],
              guile_cv_have_libc_stack_end=yes,
              guile_cv_have_libc_stack_end=no)])
 AC_MSG_RESULT($guile_cv_have_libc_stack_end)

-- 
Matthias Koeppe -- http://www.math.uni-magdeburg.de/~mkoeppe


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Re: [Patch] Fix configure test for __libc_stack_end

[Marius Vollmer]

Matthias Koeppe <mkoeppe@mail.math.uni-magdeburg.de> writes:

> The test for `guile_cv_have_libc_stack_end' does not work reliably
> because the compiler can optimize away the use of the variable in the
> test program.  This happened to me on Solaris with the Sun Forte C
> compiler.
> 
> Here is a patch.

Thanks!  Applied with a minor change: Although the program is never
run, I still feel nervous about printing the stack end as "%s".  I
changed that to "%p".

-- 
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