Jeff KingThe discussion about MAYBE_UNUSED over in[1] made me wonder how it was used in practice. This series cleans up a few spots where I think it is being misused.
[1] https://lore.kernel.org/git/xmqqseunxtks.fsf_-_@gitster.g/
The remaining grep hits are:
- fsmonitor has a few functions with sometimes-unused parameters based
on conditional compilation (try_to_run_foreground_daemon() and
check_for_incompatible()). This is a good use of MAYBE_UNUSED. - builtin/gc.c's check_crontab_process(). The whole function is marked
as MAYBE_UNUSED here, which is a little funny. It's because
is_crontab_available() may or may not call us based on __APPLE__.
Should we conditionally define the function, too, in that case? It
would mean repeating the #ifdef. Alternatively, we could define it
like this: #ifdef __APPLE__
static int check_crontab_process(const char *cmd UNUSED)
{
return 0;
}
#else
static int check_crontab_process(const char *cmd UNUSED)
{
[...the real function...]
}
#endif But I think we're getting into "well, this is how I would have
written it" territory, and it doesn't matter much either way in
practice. It's probably better to just leave it alone. - commit-slab marks auto-generated static functions with MAYBE_UNUSED,
since it doesn't know which ones actually need to be instantiated.
This was the original thing we added MAYBE_UNUSED for.- khash does something similar when auto-generating functions.
- test_bitmap_commits() marks a local variable as MAYBE_UNUSED! In
fact it's completely unused by the function itself, but the macro
expansion of kh_foreach() assigns to it. So we need the variable to
exist to pass into the macro, but the compiler warning is triggered
on the expanded code. We have kh_foreach_value(), but not
kh_foreach_key(), which is what we'd want here. It wouldn't be hard
to add it, but the MAYBE_UNUSED here is doing a fine job of
suppressing the warning (and presumably an optimizing compiler
removes the useless assignment).I prepared this on top of what's queued in jk/unused-parameters (which helps with making sure the annotations are all correct), but it could be applied separately.
[1/2]: gc: drop MAYBE_UNUSED annotation from used parameter [2/2]: grep: prefer UNUSED to MAYBE_UNUSED for pcre allocators
builtin/gc.c | 2 +- grep.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-)
-Peff
