From: Jeff King <peff@peff.net>
To: "Carlo Marcelo Arenas Belón" <carenas@gmail.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH] remote: avoid -Wunused-but-set-variable in gcc with -DNDEBUG
Date: Thu, 2 Sep 2021 04:52:53 -0400 [thread overview]
Message-ID: <YTCQ5aJXPMTUpKs8@coredump.intra.peff.net> (raw)
In-Reply-To: <YTCO56kbtQbODDeK@coredump.intra.peff.net>
[dropped Patrick from cc; that address isn't valid anymore, and he's not
active in Git development these days]
On Thu, Sep 02, 2021 at 04:44:23AM -0400, Jeff King wrote:
> > this breaks the build with -DNDEBUG because the assert gets compiled
> > out and therefore the variable used to check is never used
>
> Right, this is the real point of the patch. Compiling with NDEBUG will
> result in a warning.
Taking all of my suggestions together yields something like:
-- >8 --
From: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Subject: [PATCH] remote: avoid -Wunused-but-set-variable in gcc with -DNDEBUG
In make_remote(), we store the return value of hashmap_put() and check
it using assert(), but don't otherwise use it. If Git is compiled with
NDEBUG, then the assert() becomes a noop, and nobody looks at the
variable at all. This causes some compilers to produce warnings.
Let's switch it instead to a BUG(). This accomplishes the same thing,
but is always compiled in (and we don't have to worry about the cost;
the check is cheap, and this is not a hot code path).
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
---
remote.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/remote.c b/remote.c
index dfb863d808..40e785da38 100644
--- a/remote.c
+++ b/remote.c
@@ -135,7 +135,7 @@ static inline void init_remotes_hash(void)
static struct remote *make_remote(const char *name, int len)
{
- struct remote *ret, *replaced;
+ struct remote *ret;
struct remotes_hash_key lookup;
struct hashmap_entry lookup_entry, *e;
@@ -162,8 +162,8 @@ static struct remote *make_remote(const char *name, int len)
remotes[remotes_nr++] = ret;
hashmap_entry_init(&ret->ent, lookup_entry.hash);
- replaced = hashmap_put_entry(&remotes_hash, ret, ent);
- assert(replaced == NULL); /* no previous entry overwritten */
+ if (hashmap_put_entry(&remotes_hash, ret, ent))
+ BUG("hashmap_put overwrote entry after hashmap_get returned NULL");
return ret;
}
--
2.33.0.446.g793367f49a
next prev parent reply other threads:[~2021-09-02 8:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-02 7:36 [PATCH] remote: avoid -Wunused-but-set-variable in gcc with -DNDEBUG Carlo Marcelo Arenas Belón
2021-09-02 8:44 ` Jeff King
2021-09-02 8:52 ` Jeff King [this message]
2021-09-02 9:10 ` Carlo Arenas
2021-09-02 20:13 ` Junio C Hamano
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