[BZ #16195] Fix build warnings from systemtap probes in non-systemtap configurations

Joseph pointed out in the bug report (and in an earlier thread) that
systemtap probes cause build time warnings like the following:

    ../sysdeps/ieee754/dbl-64/e_atan2.c:602:4: warning: the address of
    'p' will always evaluate as 'true' [-Waddress]

due to the fact that we're now passing non-weak variables to
LIBC_PROBE in the libm probes.  This happens only on configurations
that do not enable systemtap.  The macro definition of LIBC_PROBE in
this case only acts as a sanity checker to ensure that the number
parameters passed to LIBC_PROBE is equal to the argument count
parameter passed before it.  This can be done in a much simpler manner
by just adding a macro definition for each number of arguments.  I am
assuming here that we don't really want to bother with supporting
LIBC_PROBE with an indeterminate number of arguments and if there is a
need for a probe to have more data than what is currently supported (4
arguments), one could simply add an additional macro here.

1 files changed, 8 insertions, 7 deletions

diff --git a/include/stap-probe.h b/include/stap-probe.h
index 5f72556..e296350 100644
--- a/include/stap-probe.h
+++ b/include/stap-probe.h
@@ -61,13 +61,14 @@
 
 # ifndef __ASSEMBLER__
 /* Evaluate all the arguments and verify that N matches their number.  */
-#  define LIBC_PROBE(name, n, ...)					      \
-  do {									      \
-    _Bool __libc_probe_args[] = { 0, ## __VA_ARGS__ };			      \
-    _Bool __libc_probe_verify_n[(sizeof __libc_probe_args / sizeof (_Bool))   \
-                                == n + 1 ? 1 : -1];			      \
-    (void) __libc_probe_verify_n;					      \
-  } while (0)
+#define LIBC_PROBE(name, n, ...) STAP_PROBE##n (__VA_ARGS__)
+
+#define STAP_PROBE0()
+#define STAP_PROBE1(a1)
+#define STAP_PROBE2(a1, a2)
+#define STAP_PROBE3(a1, a2, a3)
+#define STAP_PROBE4(a1, a2, a3, a4)
+
 # else
 #  define LIBC_PROBE(name, n, ...)		/* Nothing.  */
 # endif