From: Jonathan Nieder <jrnieder@gmail.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
"brian m . carlson" <sandals@crustytoothpaste.net>,
Jeff King <peff@peff.net>
Subject: Re: [PATCH 1/2] git-compat-util.h: clarify comment on GCC-specific code
Date: Thu, 20 May 2021 19:06:41 -0700 [thread overview]
Message-ID: <YKcVsfsLZqrkMjXl@google.com> (raw)
In-Reply-To: <patch-1.2-a8cc05cf56f-20210412T105422Z-avarab@gmail.com>
Hi,
Ævar Arnfjörð Bjarmason wrote:
> Change a comment added in e208f9cc757 (make error()'s constant return
> value more visible, 2012-12-15) to note that the code doesn't only
> depend on variadic macros, which have been a hard dependency since
> 765dc168882 (git-compat-util: always enable variadic macros,
> 2021-01-28), but also on GCC's handling of __VA_ARGS__. The commit
> message for e208f9cc757 made this clear, but the comment it added did
> not.
>
> See also e05bed960d3 (trace: add 'file:line' to all trace output,
> 2014-07-12) for another comment about GNUC's handling of __VA_ARGS__.
>
> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> ---
> git-compat-util.h | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
Oh, subtle. In fact, I believe 9798f7e5f9 (Use __VA_ARGS__ for all of
error's arguments, 2013-02-08) got rid of the gcc-ism, so we could do
the following instead.
(See section 6.10.3.10 for a description of
#define f(...) g(__VA_ARGS__)
in the C99 standard.)
Thanks,
Jonathan
-- >8 --
Subject: error: use macro-based static analysis aid on non-gcc, too
In the rest of Git, we check HAVE_VARIADIC_MACROS (which is
unconditionally defined to true as a way to discover platforms that do
not support it) to guard code that requires variadic macro support.
This variadic macro is a bit older, so it uses a __GNUC__ check
instead. Switch to use of HAVE_VARIADIC_MACROS here as well, so more
compilers can get the benefit of knowing at compile time that error()
always returns -1.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
git-compat-util.h | 22 ++++++++++------------
1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/git-compat-util.h b/git-compat-util.h
index a508dbe5a3..ca22b11760 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -483,14 +483,19 @@ void warning_errno(const char *err, ...) __attribute__((format (printf, 1, 2)));
#include <openssl/x509v3.h>
#endif /* NO_OPENSSL */
+/*
+ * This is always defined as a first step towards making the use of variadic
+ * macros unconditional. If it causes compilation problems on your platform,
+ * please report it to the Git mailing list at git@vger.kernel.org.
+ */
+#define HAVE_VARIADIC_MACROS 1
+
/*
* Let callers be aware of the constant return value; this can help
- * gcc with -Wuninitialized analysis. We restrict this trick to gcc, though,
- * because some compilers may not support variadic macros. Since we're only
- * trying to help gcc, anyway, it's OK; other compilers will fall back to
- * using the function as usual.
+ * gcc with -Wuninitialized analysis. Compilers without support for variadic
+ * macros will fall back to using the function as usual.
*/
-#if defined(__GNUC__)
+#ifdef HAVE_VARIADIC_MACROS
static inline int const_error(void)
{
return -1;
@@ -1192,13 +1197,6 @@ static inline int regexec_buf(const regex_t *preg, const char *buf, size_t size,
#endif
#endif
-/*
- * This is always defined as a first step towards making the use of variadic
- * macros unconditional. If it causes compilation problems on your platform,
- * please report it to the Git mailing list at git@vger.kernel.org.
- */
-#define HAVE_VARIADIC_MACROS 1
-
/* usage.c: only to be used for testing BUG() implementation (see test-tool) */
extern int BUG_exit_code;
--
2.31.1.818.g46aad6cb9e
next prev parent reply other threads:[~2021-05-21 2:06 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-10 15:21 [PATCH 00/15] SHA-256 / SHA-1 interop, part 1 brian m. carlson
2021-04-10 15:21 ` [PATCH 01/15] sha1-file: allow hashing objects literally with any algorithm brian m. carlson
2021-04-15 8:55 ` Denton Liu
2021-04-15 23:03 ` brian m. carlson
2021-04-16 15:04 ` Ævar Arnfjörð Bjarmason
2021-04-16 18:55 ` Junio C Hamano
2021-04-10 15:21 ` [PATCH 02/15] builtin/hash-object: allow literally hashing with a given algorithm brian m. carlson
2021-04-11 8:52 ` Ævar Arnfjörð Bjarmason
2021-04-11 21:07 ` brian m. carlson
2021-04-16 15:21 ` Ævar Arnfjörð Bjarmason
2021-04-16 17:27 ` Ævar Arnfjörð Bjarmason
2021-04-10 15:21 ` [PATCH 03/15] cache: add an algo member to struct object_id brian m. carlson
2021-04-11 11:55 ` Ævar Arnfjörð Bjarmason
2021-04-11 21:37 ` brian m. carlson
2021-04-13 12:12 ` Derrick Stolee
2021-04-14 1:08 ` brian m. carlson
2021-04-15 8:47 ` Ævar Arnfjörð Bjarmason
2021-04-15 23:51 ` brian m. carlson
2021-04-10 15:21 ` [PATCH 04/15] Always use oidread to read into " brian m. carlson
2021-04-10 15:21 ` [PATCH 05/15] hash: add a function to finalize object IDs brian m. carlson
2021-04-10 15:21 ` [PATCH 06/15] Use the final_oid_fn to finalize hashing of " brian m. carlson
2021-04-10 15:21 ` [PATCH 07/15] builtin/pack-redundant: avoid casting buffers to struct object_id brian m. carlson
2021-04-10 15:21 ` [PATCH 08/15] cache: compare the entire buffer for " brian m. carlson
2021-04-11 8:17 ` Chris Torek
2021-04-11 11:36 ` Ævar Arnfjörð Bjarmason
2021-04-11 21:05 ` brian m. carlson
2021-04-10 15:21 ` [PATCH 09/15] hash: set and copy algo field in " brian m. carlson
2021-04-11 11:57 ` Ævar Arnfjörð Bjarmason
2021-04-11 21:48 ` brian m. carlson
2021-04-11 22:12 ` Ævar Arnfjörð Bjarmason
2021-04-11 23:52 ` brian m. carlson
2021-04-12 11:02 ` [PATCH 0/2] C99: harder dependency on variadic macros Ævar Arnfjörð Bjarmason
2021-04-12 11:02 ` [PATCH 1/2] git-compat-util.h: clarify comment on GCC-specific code Ævar Arnfjörð Bjarmason
2021-04-13 7:57 ` Jeff King
2021-04-13 21:07 ` Junio C Hamano
2021-04-14 5:21 ` Jeff King
2021-04-14 6:12 ` Ævar Arnfjörð Bjarmason
2021-04-14 7:31 ` Jeff King
2021-05-21 2:06 ` Jonathan Nieder [this message]
2021-04-12 11:02 ` [PATCH 2/2] C99 support: remove non-HAVE_VARIADIC_MACROS code Ævar Arnfjörð Bjarmason
2021-04-12 17:58 ` Junio C Hamano
2021-04-13 8:00 ` Jeff King
2021-05-21 2:50 ` Jonathan Nieder
2021-04-12 12:14 ` [PATCH 0/2] C99: harder dependency on variadic macros Bagas Sanjaya
2021-04-12 12:41 ` Ævar Arnfjörð Bjarmason
2021-04-12 22:57 ` brian m. carlson
2021-04-12 23:19 ` Junio C Hamano
2022-01-28 11:11 ` [PATCH v2 0/2] C99: remove hardcoded-out !HAVE_VARIADIC_MACROS code Ævar Arnfjörð Bjarmason
2022-01-28 11:11 ` [PATCH v2 1/2] git-compat-util.h: clarify GCC v.s. C99-specific in comment Ævar Arnfjörð Bjarmason
2022-01-28 11:11 ` [PATCH v2 2/2] C99: remove hardcoded-out !HAVE_VARIADIC_MACROS code Ævar Arnfjörð Bjarmason
2022-01-28 22:40 ` Junio C Hamano
2022-02-19 10:41 ` [PATCH v3 0/3] C99: remove dead " Ævar Arnfjörð Bjarmason
2022-02-19 10:41 ` [PATCH v3 1/3] git-compat-util.h: clarify GCC v.s. C99-specific in comment Ævar Arnfjörð Bjarmason
2022-02-19 10:41 ` [PATCH v3 2/3] C99: remove hardcoded-out !HAVE_VARIADIC_MACROS code Ævar Arnfjörð Bjarmason
2022-02-19 10:41 ` [PATCH v3 3/3] trace.h: remove never-used TRACE_CONTEXT Ævar Arnfjörð Bjarmason
2022-02-20 12:02 ` Junio C Hamano
2022-02-20 12:38 ` Ævar Arnfjörð Bjarmason
2022-02-20 20:12 ` Junio C Hamano
2022-02-21 16:05 ` [PATCH v4 0/2] C99: remove dead !HAVE_VARIADIC_MACROS code Ævar Arnfjörð Bjarmason
2022-02-21 16:05 ` [PATCH v4 1/2] git-compat-util.h: clarify GCC v.s. C99-specific in comment Ævar Arnfjörð Bjarmason
2022-02-21 16:05 ` [PATCH v4 2/2] C99: remove hardcoded-out !HAVE_VARIADIC_MACROS code Ævar Arnfjörð Bjarmason
2021-04-12 10:53 ` [PATCH 09/15] hash: set and copy algo field in struct object_id Junio C Hamano
2021-04-12 11:13 ` Ævar Arnfjörð Bjarmason
2021-04-10 15:21 ` [PATCH 10/15] hash: provide per-algorithm null OIDs brian m. carlson
2021-04-11 14:03 ` Junio C Hamano
2021-04-11 21:51 ` brian m. carlson
2021-04-10 15:21 ` [PATCH 11/15] builtin/show-index: set the algorithm for object IDs brian m. carlson
2021-04-10 15:21 ` [PATCH 12/15] commit-graph: don't store file hashes as struct object_id brian m. carlson
2021-04-10 15:21 ` [PATCH 13/15] builtin/pack-objects: avoid using struct object_id for pack hash brian m. carlson
2021-04-10 15:21 ` [PATCH 14/15] hex: default to the_hash_algo on zero algorithm value brian m. carlson
2021-04-10 15:21 ` [PATCH 15/15] hex: print objects using the hash algorithm member brian m. carlson
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