threads / patch / 21108

patchRe: [PATCH] Fix some printf format warnings

Subject: Re: [PATCH] Fix some printf format warnings

## tl;dr

2 messages between Sep 30, 2009 and Oct 1, 2009. Diffs are folded; open one to read it.

replies: 1people: 2as markdown or json

Ramsay Jones· Sep 30, 2009, 18:49 UTC · lore

[PATCH] Fix some printf format warnings

commit 51ea551 ("make sure byte swapping is optimal for git" 2009-08-18) introduced a "sane definition for ntohl()/htonl()" for use on some GNU C platforms. Unfortunately, for some of these platforms, this results in the introduction of a problem which is essentially the reverse of a problem that commit 6e1c234 ("Fix some warnings (on cygwin) to allow -Werror" 2008-07-3) was intended to fix.

In particular, on platforms where the uint32_t type is defined to be unsigned long, the return type of the new ntohl()/htonl() is causing gcc to issue printf format warnings, such as:

    warning: long unsigned int format, unsigned int arg (arg 3)

(nine such warnings, covering six different files). The earlier commit (6e1c234) needed to suppress these same warnings, except that the types were in the opposite direction; namely the format specifier ("%u") was 'unsigned int' and the argument type (ie the return type of ntohl()) was 'long unsigned int' (aka uint32_t).

In order to suppress these warnings, the earlier commit used the (C99) PRIu32 format specifier, since the definition of this macro is suitable for use with the uint32_t type on that platform. This worked because the return type of the (original) platform ntohl()/htonl() functions was uint32_t.

In order to suppress these warnings, we change the return type of the new byte swapping functions in the compat/bswap.h header file from 'unsigned int' to uint32_t.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
---
 compat/bswap.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

Show changes to compat/bswap.h +2 −2

diff --git a/compat/bswap.h b/compat/bswap.h
index 7246a12..5cc4acb 100644
--- a/compat/bswap.h
+++ b/compat/bswap.h
@@ -9,7 +9,7 @@
  * Default version that the compiler ought to optimize properly with
  * constant values.
  */
-static inline unsigned int default_swab32(unsigned int val)
+static inline uint32_t default_swab32(uint32_t val)
 {
 	return (((val & 0xff000000) >> 24) |
 		((val & 0x00ff0000) >>  8) |
@@ -20,7 +20,7 @@ static inline unsigned int default_swab32(unsigned int val)
 #if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
 
 #define bswap32(x) ({ \
-	unsigned int __res; \
+	uint32_t __res; \
 	if (__builtin_constant_p(x)) { \
 		__res = default_swab32(x); \
 	} else { \

-- 
1.6.4

Nicolas Pitre· Oct 1, 2009, 17:29 UTC · re: Ramsay Jones · lore

On Wed, 30 Sep 2009, Ramsay Jones wrote:

Show 32 quoted lines

> 
> commit 51ea551 ("make sure byte swapping is optimal for git"
> 2009-08-18) introduced a "sane definition for ntohl()/htonl()"
> for use on some GNU C platforms. Unfortunately, for some of
> these platforms, this results in the introduction of a problem
> which is essentially the reverse of a problem that commit 6e1c234
> ("Fix some warnings (on cygwin) to allow -Werror" 2008-07-3) was
> intended to fix.
> 
> In particular, on platforms where the uint32_t type is defined
> to be unsigned long, the return type of the new ntohl()/htonl()
> is causing gcc to issue printf format warnings, such as:
> 
>     warning: long unsigned int format, unsigned int arg (arg 3)
> 
> (nine such warnings, covering six different files). The earlier
> commit (6e1c234) needed to suppress these same warnings, except
> that the types were in the opposite direction; namely the format
> specifier ("%u") was 'unsigned int' and the argument type (ie the
> return type of ntohl()) was 'long unsigned int' (aka uint32_t).
> 
> In order to suppress these warnings, the earlier commit used the
> (C99) PRIu32 format specifier, since the definition of this macro
> is suitable for use with the uint32_t type on that platform.
> This worked because the return type of the (original) platform
> ntohl()/htonl() functions was uint32_t.
> 
> In order to suppress these warnings, we change the return type of
> the new byte swapping functions in the compat/bswap.h header file
> from 'unsigned int' to uint32_t.
> 
> Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>

Acked-by: Nicolas Pitre <nico@fluxnic.net>

Show 30 quoted lines

> ---
>  compat/bswap.h |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/compat/bswap.h b/compat/bswap.h
> index 7246a12..5cc4acb 100644
> --- a/compat/bswap.h
> +++ b/compat/bswap.h
> @@ -9,7 +9,7 @@
>   * Default version that the compiler ought to optimize properly with
>   * constant values.
>   */
> -static inline unsigned int default_swab32(unsigned int val)
> +static inline uint32_t default_swab32(uint32_t val)
>  {
>  	return (((val & 0xff000000) >> 24) |
>  		((val & 0x00ff0000) >>  8) |
> @@ -20,7 +20,7 @@ static inline unsigned int default_swab32(unsigned int val)
>  #if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
>  
>  #define bswap32(x) ({ \
> -	unsigned int __res; \
> +	uint32_t __res; \
>  	if (__builtin_constant_p(x)) { \
>  		__res = default_swab32(x); \
>  	} else { \
> -- 
> 1.6.4
> 
>