[libvirt] [PATCH] tests: command: Fix build on ppc64/aarch64

[Martin Kletzander]

On Thu, Jul 14, 2016 at 10:17:56AM +0200, Andrea Bolognani wrote:
>On Thu, 2016-07-14 at 08:30 +0200, Martin Kletzander wrote:
>> > Commit ca10bb040fcf introduced a new test that fails to build
>> > on at least some architectures:
>> > 
>> >  commandtest.c: In function 'test25':
>> >  commandtest.c:1121:5: error: comparison is always true due to
>> >                        limited range of data type [-Werror=type-limits]
>> >    if (rv >= 0) {
>> >    ^
>> > 
>> > Change the type of 'rv' from char to int, which is the proper
>> > return type for virCommandExec() anyway.
>> > ---
>> > Posting this to the list so that Michal/others can chime in.
>> > 
>> > Using int instead of char seems completely safe here, and in
>> > fact should probably have been the right choice from the start.
>> > 
>> > On the other hand, I would expect this kind of error if we were
>> > using unsigned char, not plain char... By the way, changing it
>> > to signed char is another way to get the code to compile again
>> > on ppc64/aarch64.
>> 
>> Souns about right to me.  The byte sent over the pipe is usually just
>> char because we simply don't need anything else, but this time around
>> there's an exception from what I remember from the rest of the code and
>> that is that the value is used as an integer later on (other times we
>> just throw it away or check if it's 0 or 1).  So ACK.
>
>I still don't get why this silly C program
>
>  #include <stdio.h>
>
>  int
>  main(int argc,
>       char **argv)
>  {
>      char a = -1;
>
>      if (a >= 0) {
>          printf("positive\n");
>      }
>
>      return 0;
>  }
>
>compiles just fine with -Wtype-limits -Werror on x86_64, but
>fails with the same error as above on ppc64 and aarch64.
>
>Isn't char supposed to be signed unless otherwise specified?
>Or is char being signed or unsigned an implementation choice?
>
>Anyway, pushed.
>

Simple search found out this http://stackoverflow.com/a/2054941

>-- 
>Andrea Bolognani / Red Hat / Virtualization
>
>--
>libvir-list mailing list
>libvir-list at redhat.com
>https://www.redhat.com/mailman/listinfo/libvir-list
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