linux-kernel - Error while building with GCC 15

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Message-ID: <mb6h75yendy2bxgivjffp65h4zwkwxbehxdloce4hlunfdbvig@rdweinlcy2a6>
Date: Sat, 11 Jan 2025 20:38:56 +0530
From: Brahmajit <brahmajit.xyz@...il.com>
To: dhowells@...hat.com
Cc: netfs@...ts.linux.dev, djwong@...nel.org, 
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Error while building with GCC 15

While building with GCC 15 I noticed these build error

fs/netfs/fscache_cache.c:375:67: error: initializer-string for array of ‘char’ is too long [-Werror=unterminated-string-initialization]
  375 | static const char fscache_cache_states[NR__FSCACHE_CACHE_STATE] = "-PAEW";
      |                                                                   ^~~~~~~
cc1: all warnings being treated as errors

fs/netfs/fscache_cookie.c:32:69: error: initializer-string for array of ‘char’ is too long [-Werror=unterminated-string-initialization]
   32 | static const char fscache_cookie_states[FSCACHE_COOKIE_STATE__NR] = "-LCAIFUWRD";
      |                                                                     ^~~~~~~~~~~~
cc1: all warnings being treated as errors

This due to GCC 15 having enabled -Wunterminated-string-initialization
by default[0].

I was first planning on doing something like

--- a/fs/netfs/fscache_cache.c
+++ b/fs/netfs/fscache_cache.c
@@ -372,7 +372,7 @@ void fscache_withdraw_cache(struct fscache_cache *cache)
 EXPORT_SYMBOL(fscache_withdraw_cache);
 
 #ifdef CONFIG_PROC_FS
-static const char fscache_cache_states[NR__FSCACHE_CACHE_STATE] = "-PAEW";
+static const char fscache_cache_states[NR__FSCACHE_CACHE_STATE] = { '-', 'P', 'A', 'E', 'W' };
 
 /*
  * Generate a list of caches in /proc/fs/fscache/caches

But then I remembered I did solve a similar bug before where the
developer agreed to just increasing the array size by one[1].
So something like this:

--- a/fs/netfs/fscache_cache.c
+++ b/fs/netfs/fscache_cache.c
@@ -372,7 +372,7 @@ void fscache_withdraw_cache(struct fscache_cache *cache)
 EXPORT_SYMBOL(fscache_withdraw_cache);
 
 #ifdef CONFIG_PROC_FS
-static const char fscache_cache_states[NR__FSCACHE_CACHE_STATE] = "-PAEW";
+static const char fscache_cache_states[NR__FSCACHE_CACHE_STATE + 1] = "-PAEW";
 
 /*
  * Generate a list of caches in /proc/fs/fscache/caches

So I'm wondering which one would be more appropriate here. Would really
like some help/recommendation then I can send in the patch.

[0]: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wno-unterminated-string-initialization
[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a500f3751d3c861be7e4463c933cf467240cca5d

-- 
Regards,
Brahmajit