trace2: NULL is not allowed for va_list

Some compilers don't allow NULL to be passed for a va_list,
and e.g. "gcc (Raspbian 6.3.0-18+rpi1+deb9u1) 6.3.0 20170516"
errors out like this:
 trace2/tr2_tgt_event.c:193:18:
   error: invalid operands to binary &&
   (have ‘int’ and ‘va_list {aka __va_list}’)
    if (fmt && *fmt && ap) {
                       ^^
I couldn't find any hints that va_list and pointers can be mixed,
and no hints that they can't either. Morten Welinder comments:

"C99, Section 7.15, simply says that va_list "is an object type suitable for
holding information needed by the macros va_start, va_end, and
va_copy". So clearly not guaranteed to be mixable with pointers...

The portable solution is to use "va_list" everywhere in the callchain.
As a consequence, both trace2_region_enter_fl() and trace2_region_leave_fl()
now take a variable argument list.

Signed-off-by: Torsten Bögershausen <tboegi@web.de>
Acked-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/trace2.c b/trace2.c
index ccccd4e..8bbad56 100644
--- a/trace2.c
+++ b/trace2.c
@@ -548,10 +548,14 @@ void trace2_region_enter_printf_va_fl(const char *file, int line,
 }
 
 void trace2_region_enter_fl(const char *file, int line, const char *category,
-			    const char *label, const struct repository *repo)
+			    const char *label, const struct repository *repo, ...)
 {
+	va_list ap;
+	va_start(ap, repo);
 	trace2_region_enter_printf_va_fl(file, line, category, label, repo,
-					 NULL, NULL);
+					 NULL, ap);
+	va_end(ap);
+
 }
 
 void trace2_region_enter_printf_fl(const char *file, int line,
@@ -621,10 +625,13 @@ void trace2_region_leave_printf_va_fl(const char *file, int line,
 }
 
 void trace2_region_leave_fl(const char *file, int line, const char *category,
-			    const char *label, const struct repository *repo)
+			    const char *label, const struct repository *repo, ...)
 {
+	va_list ap;
+	va_start(ap, repo);
 	trace2_region_leave_printf_va_fl(file, line, category, label, repo,
-					 NULL, NULL);
+					 NULL, ap);
+	va_end(ap);
 }
 
 void trace2_region_leave_printf_fl(const char *file, int line,