Re: getting rid of some warnings

Re: getting rid of some warnings

[Rich Felker]

On Thu, Mar 02, 2017 at 02:37:19PM -0800, Reinoud Koornstra wrote:
> Hello Rich,
> 
> I did compile against musl using the musl-gcc build from your scripts.
> 
> ->MUSL-GCC/bin/x86_64-linux-musl-gcc -nostdinc
> -I/users/koorstra/MUSL-GCC/x86_64-linux-musl/include/ -Wall -g -o
> split_buff split_buff.c
> In file included from
> /users/koorstra/MUSL-GCC/x86_64-linux-musl/include/sys/types.h:70:0,
>                  from split_buff.c:4:
> /users/koorstra/MUSL-GCC/x86_64-linux-musl/include/endian.h: In
> function '__bswap32':
> /users/koorstra/MUSL-GCC/x86_64-linux-musl/include/endian.h:32:25:
> warning: suggest parentheses around arithmetic in operand of '|'
> [-Wparentheses]
>   return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
>                    ~~~~~~^~~~~~~

This happened because you're not just using the musl-gcc wrapper
script, but passing -nostdinc and -I to get the system headers.
Instead either configure for the right include path so you don't need
to do this, or use -isystem instead of -I.

> /users/koorstra/MUSL-GCC/x86_64-linux-musl/include/endian.h:32:41:
> warning: suggest parentheses around arithmetic in operand of '|'
> [-Wparentheses]
>   return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
>                                    ~~~~~~^~~~~~~~~
> /users/koorstra/MUSL-GCC/x86_64-linux-musl/include/endian.h: In
> function '__bswap64':
> /users/koorstra/MUSL-GCC/x86_64-linux-musl/include/endian.h:37:23:
> warning: suggest parentheses around '+' inside  <<' [-Wparentheses]
>   return __bswap32(__x)+0ULL<<32 | __bswap32(__x>>32);
>          ~~~~~~~~~~~~~~^~~~~
>  koorstra@lnxpefer ~
> ->readelf -d split_buff | grep NEEDED
>  0x0000000000000001 (NEEDED)             Shared library: [libc.so]
> 
> 
>  koorstra@lnxpefer ~
> ->./split_buff
> -bash: ./split_buff: /lib/ld-musl-x86_64.so.1: bad ELF interpreter: No
> such file or directory
> 
> How can I get rid of these warnings?
> Also, I guess I need to set the default library paths different?
> Any advice for this?
> Thanks,

If you dynamic link, the dynamic linker ("ELF interpreter") has to be
present at runtime. Your options are:

1. Install it in /lib as above.
2. Static link.
3. Explicitly invoke it from another location to run the program:
   /path/to/ld-musl-x86_64.so.1 ./split_buff ...
4. Configure musl with a different --syslibdir. Note that if you do
   this, programs you link will only work with ld-musl installed in
   the location you have it on your system, and won't be portable to
   standard musl-based systems.

I would recommend option 1 if it's your own system and you can, option
2 or 3 for something you need to ship (you can wrap option 3 with a
script), and option 4 if this is just for testing or personal use (not
shipping) on a system you don't have root on.

Rich

Re: getting rid of some warnings

[Reinoud Koornstra]

On Thu, Mar 2, 2017 at 4:27 PM, Rich Felker <dalias@aerifal.cx> wrote:
> On Thu, Mar 02, 2017 at 02:37:19PM -0800, Reinoud Koornstra wrote:
>> Hello Rich,
>>
>> I did compile against musl using the musl-gcc build from your scripts.
>>
>> ->MUSL-GCC/bin/x86_64-linux-musl-gcc -nostdinc
>> -I/users/koorstra/MUSL-GCC/x86_64-linux-musl/include/ -Wall -g -o
>> split_buff split_buff.c
>> In file included from
>> /users/koorstra/MUSL-GCC/x86_64-linux-musl/include/sys/types.h:70:0,
>>                  from split_buff.c:4:
>> /users/koorstra/MUSL-GCC/x86_64-linux-musl/include/endian.h: In
>> function '__bswap32':
>> /users/koorstra/MUSL-GCC/x86_64-linux-musl/include/endian.h:32:25:
>> warning: suggest parentheses around arithmetic in operand of '|'
>> [-Wparentheses]
>>   return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
>>                    ~~~~~~^~~~~~~
>
> This happened because you're not just using the musl-gcc wrapper
> script, but passing -nostdinc and -I to get the system headers.
> Instead either configure for the right include path so you don't need
> to do this, or use -isystem instead of -I.

Ah, I couldn't find that script, that why I used the currently options.
Where is that script located? I did a search on the fs for musl-gcc,
but no results.
Also, I tried your suggestion: ->MUSL-GCC/bin/x86_64-linux-musl-gcc
-isystem -Wall -g -o split_buff split_buff.c
and that did compile without any warnings. The code i'm compiling is
own written code that doesn't yet have a config script.

>
>> /users/koorstra/MUSL-GCC/x86_64-linux-musl/include/endian.h:32:41:
>> warning: suggest parentheses around arithmetic in operand of '|'
>> [-Wparentheses]
>>   return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
>>                                    ~~~~~~^~~~~~~~~
>> /users/koorstra/MUSL-GCC/x86_64-linux-musl/include/endian.h: In
>> function '__bswap64':
>> /users/koorstra/MUSL-GCC/x86_64-linux-musl/include/endian.h:37:23:
>> warning: suggest parentheses around '+' inside  <<' [-Wparentheses]
>>   return __bswap32(__x)+0ULL<<32 | __bswap32(__x>>32);
>>          ~~~~~~~~~~~~~~^~~~~
>>  koorstra@lnxpefer ~
>> ->readelf -d split_buff | grep NEEDED
>>  0x0000000000000001 (NEEDED)             Shared library: [libc.so]
>>
>>
>>  koorstra@lnxpefer ~
>> ->./split_buff
>> -bash: ./split_buff: /lib/ld-musl-x86_64.so.1: bad ELF interpreter: No
>> such file or directory
>>
>> How can I get rid of these warnings?
>> Also, I guess I need to set the default library paths different?
>> Any advice for this?
>> Thanks,
>
> If you dynamic link, the dynamic linker ("ELF interpreter") has to be
> present at runtime. Your options are:
>
> 1. Install it in /lib as above.
> 2. Static link.
> 3. Explicitly invoke it from another location to run the program:
>    /path/to/ld-musl-x86_64.so.1 ./split_buff ...
> 4. Configure musl with a different --syslibdir. Note that if you do
>    this, programs you link will only work with ld-musl installed in
>    the location you have it on your system, and won't be portable to
>    standard musl-based systems.
>
> I would recommend option 1 if it's your own system and you can, option
> 2 or 3 for something you need to ship (you can wrap option 3 with a
> script), and option 4 if this is just for testing or personal use (not
> shipping) on a system you don't have root on.

Thanks, the following worked for me too:
./MUSL-GCC/x86_64-linux-musl/lib/libc.so split_buff
Other issue is that ld-musl-x86_64.so.1 is a symlink to /lib/libc.so
........ which isn't the right one.
This can be remedied with changing the -syslibdir as you mentioned correct?
Thanks,

Reinoud.

>
> Rich