Fix warnings when build with clang

Fix warnings when build with clang

[Zhao, Weiming]

[-- Attachment #1: Type: text/plain, Size: 674 bytes --]

Clang gives warnings about the missing parentheses for bitwise ops.

It's not functional but just code readability.

musl-m3/include/endian.h:32:25: warning: '&' within '|' 
[-Wbitwise-op-parentheses]
         return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
                        ~ ~~~~~~^~~~~~~


musl-m3/include/endian.h:37:23: warning: operator '<<' has lower 
precedence than '+'; '+' will be evaluated first [-Wshift-op-parentheses]
         return __bswap32(__x)+0ULL<<32 | __bswap32(__x>>32);
                ~~~~~~~~~~~~~~^~~~~~~


Thanks,
Weiming

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation


[-- Attachment #2: musl.patch --]
[-- Type: text/plain, Size: 589 bytes --]

diff --git a/include/endian.h b/include/endian.h
index 1bd4445..88c3347 100644
--- a/include/endian.h
+++ b/include/endian.h
@@ -29,12 +29,12 @@ static __inline uint16_t __bswap16(uint16_t __x)
 
 static __inline uint32_t __bswap32(uint32_t __x)
 {
-	return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
+	return __x>>24 | (__x>>8&0xff00) | (__x<<8&0xff0000) | __x<<24;
 }
 
 static __inline uint64_t __bswap64(uint64_t __x)
 {
-	return __bswap32(__x)+0ULL<<32 | __bswap32(__x>>32);
+	return (__bswap32(__x)+0ULL)<<32 | __bswap32(__x>>32);
 }
 
 #if __BYTE_ORDER == __LITTLE_ENDIAN

Re: Fix warnings when build with clang

[Szabolcs Nagy]

* Zhao, Weiming <weimingz@codeaurora.org> [2016-06-24 17:18:23 -0700]:
> Clang gives warnings about the missing parentheses for bitwise ops.
> 
> It's not functional but just code readability.
> 
> musl-m3/include/endian.h:32:25: warning: '&' within '|'
> [-Wbitwise-op-parentheses]
>         return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
>                        ~ ~~~~~~^~~~~~~

if clang warns about system headers that's a clang bug.

Re: Fix warnings when build with clang

[weimingz]

On 2016-06-25 02:37, Szabolcs Nagy wrote:
> * Zhao, Weiming <weimingz@codeaurora.org> [2016-06-24 17:18:23 -0700]:
>> Clang gives warnings about the missing parentheses for bitwise ops.
>> 
>> It's not functional but just code readability.
>> 
>> musl-m3/include/endian.h:32:25: warning: '&' within '|'
>> [-Wbitwise-op-parentheses]
>>         return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
>>                        ~ ~~~~~~^~~~~~~
> 
> if clang warns about system headers that's a clang bug.

The endian.h is a musl file.

Re: Fix warnings when build with clang

[Rich Felker]

On Mon, Jun 27, 2016 at 10:01:52AM -0700, weimingz@codeaurora.org wrote:
> On 2016-06-25 02:37, Szabolcs Nagy wrote:
> >* Zhao, Weiming <weimingz@codeaurora.org> [2016-06-24 17:18:23 -0700]:
> >>Clang gives warnings about the missing parentheses for bitwise ops.
> >>
> >>It's not functional but just code readability.
> >>
> >>musl-m3/include/endian.h:32:25: warning: '&' within '|'
> >>[-Wbitwise-op-parentheses]
> >>        return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
> >>                       ~ ~~~~~~^~~~~~~
> >
> >if clang warns about system headers that's a clang bug.
> 
> The endian.h is a musl file.

Right, which is why it's a system header.

Rich

Re: Fix warnings when build with clang

[Zhao, Weiming]

I don't think it's a compiler bug. Neither a functionality issue in MUSL.

Its a warning about code readability / sanity and we can fix it in 2 
seconds, which can make build process looks more clean.

Weiming


On 6/27/2016 10:21 AM, Rich Felker wrote:
> On Mon, Jun 27, 2016 at 10:01:52AM -0700, weimingz@codeaurora.org wrote:
>> On 2016-06-25 02:37, Szabolcs Nagy wrote:
>>> * Zhao, Weiming <weimingz@codeaurora.org> [2016-06-24 17:18:23 -0700]:
>>>> Clang gives warnings about the missing parentheses for bitwise ops.
>>>>
>>>> It's not functional but just code readability.
>>>>
>>>> musl-m3/include/endian.h:32:25: warning: '&' within '|'
>>>> [-Wbitwise-op-parentheses]
>>>>         return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
>>>>                        ~ ~~~~~~^~~~~~~
>>> if clang warns about system headers that's a clang bug.
>> The endian.h is a musl file.
> Right, which is why it's a system header.
>
> Rich

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

Re: Fix warnings when build with clang

[Luca Barbato]

On 27/06/16 19:21, Rich Felker wrote:
> On Mon, Jun 27, 2016 at 10:01:52AM -0700, weimingz@codeaurora.org wrote:
>> On 2016-06-25 02:37, Szabolcs Nagy wrote:
>>> * Zhao, Weiming <weimingz@codeaurora.org> [2016-06-24 17:18:23 -0700]:
>>>> Clang gives warnings about the missing parentheses for bitwise ops.
>>>>
>>>> It's not functional but just code readability.
>>>>
>>>> musl-m3/include/endian.h:32:25: warning: '&' within '|'
>>>> [-Wbitwise-op-parentheses]
>>>>        return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
>>>>                       ~ ~~~~~~^~~~~~~
>>>
>>> if clang warns about system headers that's a clang bug.
>>
>> The endian.h is a musl file.
> 
> Right, which is why it's a system header.

I'm not sure there is a simple way to know what's a system header and
what is not, beside keeping a list.

And even in that case I'm not so sure the compiler should hide warnings
(no matter how fringe this actual warning is).

lu

Re: Fix warnings when build with clang

[Rich Felker]

On Mon, Jun 27, 2016 at 07:41:49PM +0200, Luca Barbato wrote:
> On 27/06/16 19:21, Rich Felker wrote:
> > On Mon, Jun 27, 2016 at 10:01:52AM -0700, weimingz@codeaurora.org wrote:
> >> On 2016-06-25 02:37, Szabolcs Nagy wrote:
> >>> * Zhao, Weiming <weimingz@codeaurora.org> [2016-06-24 17:18:23 -0700]:
> >>>> Clang gives warnings about the missing parentheses for bitwise ops.
> >>>>
> >>>> It's not functional but just code readability.
> >>>>
> >>>> musl-m3/include/endian.h:32:25: warning: '&' within '|'
> >>>> [-Wbitwise-op-parentheses]
> >>>>        return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
> >>>>                       ~ ~~~~~~^~~~~~~
> >>>
> >>> if clang warns about system headers that's a clang bug.
> >>
> >> The endian.h is a musl file.
> > 
> > Right, which is why it's a system header.
> 
> I'm not sure there is a simple way to know what's a system header and
> what is not, beside keeping a list.

If your compiler is automatically searching the right system header
paths for the target, it's a non-issue. If not (if you have some
hacked-together setup) then you should use -isystem rather than -I for
the system header path.

> And even in that case I'm not so sure the compiler should hide warnings
> (no matter how fringe this actual warning is).

The intent of style warning options (which this one is) is to warn
about issues in the code being compiled, where it does not meet the
policy set for the project being compiled. It's not to warn that libc
does not meet your project's arbitrary style policies. This one
happens to be turned on by -Wall I think, but there are lots of other
style-policy warning options the user could turn on which musl's
headers are cerainly not going to try to comply with, so the proper
solution is for the compiler not to apply the style policy to them.

Rich