Re: [PATCH] remote: avoid -Wunused-but-set-variable in gcc with -DNDEBUG

[Jeff King <peff@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