common-main.c: call exit(), don't return

Change the main() function to call "exit()" instead of ending with a
"return" statement. The "exit()" function is our own wrapper that
calls trace2_cmd_exit_fl() for us, from git-compat-util.h:

	#define exit(code) exit(trace2_cmd_exit_fl(__FILE__, __LINE__, (code)))

That "exit()" wrapper has been in use ever since ee4512ed481 (trace2:
create new combined trace facility, 2019-02-22).

This changes nothing about how we "exit()", as we'd invoke
"trace2_cmd_exit_fl()" in both cases due to the wrapper, this change
makes it easier to reason about this code, as we're now always
obviously relying on our "exit()" wrapper.

There is already code immediately downstream of our "main()" which has
a hard reliance on that, e.g. the various "exit()" calls downstream of
"cmd_main()" in "git.c".

We even had a comment in "t/helper/test-trace2.c" that seemed to be
confused about how the "exit()" wrapper interacted with uses of
"return", even though it was introduced in the same trace2 series in
a15860dca3f (trace2: t/helper/test-trace2, t0210.sh, t0211.sh,
t0212.sh, 2019-02-22), after the aforementioned ee4512ed481. Perhaps
it pre-dated the "exit()" wrapper?

This change makes the "trace2_cmd_exit()" macro orphaned, we now
always use "trace2_cmd_exit_fl()" directly, but let's keep that
simpler example in place. Even if we're unlikely to get another
"main()" other than the one in our "common-main.c", there's some value
in having the API documentation and example discuss a simpler version
that doesn't require an "exit()" wrapper macro.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/common-main.c b/common-main.c
index 71e21dd20a3b141bed0d37512cdc9196321dc315..eafc70718a545abc8abc1cf9cce46f175881bbd4 100644 (file)
--- a/common-main.c
+++ b/common-main.c
@@ -51,7 +51,10 @@ int main(int argc, const char **argv)
 
        result = cmd_main(argc, argv);
 
-       trace2_cmd_exit(result);
-
-       return result;
+       /*
+        * We define exit() to call trace2_cmd_exit_fl() in
+        * git-compat-util.h. Whether we reach this or exit()
+        * elsewhere we'll always run our trace2 exit handler.
+        */
+       exit(result);
 }

diff --git a/t/helper/test-trace2.c b/t/helper/test-trace2.c
index f93633f895a1926aa6ea4ca712305cccb5826a2d..59b124bb5f147f3a8cf1876230306c4fc5bdd60f 100644 (file)
--- a/t/helper/test-trace2.c
+++ b/t/helper/test-trace2.c
@@ -262,8 +262,9 @@ static int print_usage(void)
  *    [] the "cmd_name" event has been generated.
  *    [] this writes various "def_param" events for interesting config values.
  *
- * We further assume that if we return (rather than exit()), trace2_cmd_exit()
- * will be called by test-tool.c:cmd_main().
+ * We return from here and let test-tool.c::cmd_main() pass the exit
+ * code to common-main.c::main(), which will use it to call
+ * trace2_cmd_exit().
  */
 int cmd__trace2(int argc, const char **argv)
 {