diff mbox series

[v2,09/10] interpret-trailers: mark unused "unset" parameters in option callbacks

Message ID 20230831212215.GI949469@coredump.intra.peff.net (mailing list archive)
State Accepted
Commit d775365db321c9f05c12809438d3c801d7e445af
Headers show
Series more unused parameters in parseopt callbacks | expand

Commit Message

Jeff King Aug. 31, 2023, 9:22 p.m. UTC
There are a few parse-option callbacks that do not look at their "unset"
parameters, but also do not set PARSE_OPT_NONEG. At first glance this
seems like a bug, as we'd ignore "--no-if-exists", etc.

But they do work fine, because when "unset" is true, then "arg" is NULL.
And all three functions pass "arg" on to helper functions which do the
right thing with the NULL.

Note that this shortcut would not be correct if any callback used
PARSE_OPT_NOARG (in which case "arg" would be NULL but "unset" would be
false). But none of these do.

So the code is fine as-is. But we'll want to mark the unused "unset"
parameters to quiet -Wunused-parameter. I've also added a comment to
make this rather subtle situation more explicit.

Signed-off-by: Jeff King <peff@peff.net>
---
I looked at another BUG_ON here, but it was just so ugly and one-off
that I preferred just adding the comments.

 builtin/interpret-trailers.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/builtin/interpret-trailers.c b/builtin/interpret-trailers.c
index 6aadce6a1e..a110e69f83 100644
--- a/builtin/interpret-trailers.c
+++ b/builtin/interpret-trailers.c
@@ -24,20 +24,23 @@  static enum trailer_if_exists if_exists;
 static enum trailer_if_missing if_missing;
 
 static int option_parse_where(const struct option *opt,
-			      const char *arg, int unset)
+			      const char *arg, int unset UNUSED)
 {
+	/* unset implies NULL arg, which is handled in our helper */
 	return trailer_set_where(opt->value, arg);
 }
 
 static int option_parse_if_exists(const struct option *opt,
-				  const char *arg, int unset)
+				  const char *arg, int unset UNUSED)
 {
+	/* unset implies NULL arg, which is handled in our helper */
 	return trailer_set_if_exists(opt->value, arg);
 }
 
 static int option_parse_if_missing(const struct option *opt,
-				   const char *arg, int unset)
+				   const char *arg, int unset UNUSED)
 {
+	/* unset implies NULL arg, which is handled in our helper */
 	return trailer_set_if_missing(opt->value, arg);
 }