trace: refactor to support multiple env variables

Right now you turn all tracing off and on with GIT_TRACE. To
support new types of tracing without forcing the user to see
all of them, we will soon support turning each tracing area
on with GIT_TRACE_*.

This patch lays the groundwork by providing an interface
which does not assume GIT_TRACE. However, we still maintain
the trace_printf interface so that existing callers do not
need to be refactored.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/cache.h b/cache.h
index 08b23b2ab9..2ab1bf9383 100644
--- a/cache.h
+++ b/cache.h
@@ -1067,7 +1067,7 @@ extern void alloc_report(void);
 /* trace.c */
 __attribute__((format (printf, 1, 2)))
 extern void trace_printf(const char *format, ...);
-extern void trace_vprintf(const char *format, va_list ap);
+extern void trace_vprintf(const char *key, const char *format, va_list ap);
 __attribute__((format (printf, 2, 3)))
 extern void trace_argv_printf(const char **argv, const char *format, ...);
 extern void trace_repo_setup(const char *prefix);