Re: [PATCH] remote-http: use argv-array

[Jeff King <peff@peff.net>]

On Tue, Jul 09, 2013 at 08:05:19AM +0200, Bert Wesarg wrote:

> > +       argv_array_pushl(&args, "send-pack", "--stateless-rpc", "--helper-status");
> 
> missing NULL sentinel. GCC has the 'sentinel' [1] attribute to catch
> such errors. Or use macro magic:
> 
> void argv_array_pushl_(struct argv_array *array, ...);
> #define argv_array_pushl(array, ...) argv_array_pushl_(array, __VA_ARGS__, NULL)

Nice catch. We cannot use variadic macros, because we support pre-C99
compilers that do not have them. But the sentinel attribute is a good
idea. Here's a patch.

-- >8 --
Subject: [PATCH] argv-array: add sentinel attribute to argv_array_pushl

This attribute can help gcc notice when callers forget to add a
NULL sentinel to the end of the function. We shouldn't need
to #ifdef for other compilers, as __attribute__ is already a
no-op on non-gcc-compatible compilers.

Suggested-by: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Jeff King <peff@peff.net>
---
This is our first use of an __attribute__ that is not "noreturn" or
"format". I assume this one should be supported on other gcc-compatible
compilers like clang.

 argv-array.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/argv-array.h b/argv-array.h
index 40248d4..e805748 100644
--- a/argv-array.h
+++ b/argv-array.h
@@ -15,6 +15,7 @@ void argv_array_pushf(struct argv_array *, const char *fmt, ...);
 void argv_array_push(struct argv_array *, const char *);
 __attribute__((format (printf,2,3)))
 void argv_array_pushf(struct argv_array *, const char *fmt, ...);
+__attribute__((sentinel))
 void argv_array_pushl(struct argv_array *, ...);
 void argv_array_pop(struct argv_array *);
 void argv_array_clear(struct argv_array *);
-- 
1.8.3.rc3.24.gec82cb9