[PATCH] Fix unused malloc return value warning

[Jonathan Wakely]

On 29/08/19 21:54 +0200, François Dumont wrote:
>Hi
>
>Â Â Â  I am having this warning:
>
>/home/fdt/dev/gcc/git/libstdc++-v3/testsuite/util/testsuite_performance.h:170: 
>attention: ignoring return value of « void* malloc(size_t) » declared 
>with attribute « warn_unused_result » [-Wunused-result]
>Â  170 |Â Â Â Â Â Â  malloc(0); // Needed for some implementations.
>
>Â Â Â  Ok to fix it with attached patch ?

OK for trunk.

>Â Â Â  It seems trivial but I wonder if I shouldn't keep the malloc 
>returned pointer and free it properly ?

It's not causing any problems (it's only the testsuite) so let's not
worry about it.

>Â Â Â  Or maybe just remove the malloc cause there is not clear comment 
>explaining why it's needed and I haven't found much in SVN audit 
>trail.

The comment says it's needed, so let's assume that's true.

>Â Â Â  * testsuite_files/util/testsuite_performance.h
>Â Â Â  (resource_counter::start): Ignore unused malloc(0) result.
>
>François
>

>diff --git a/libstdc++-v3/testsuite/util/testsuite_performance.h b/libstdc++-v3/testsuite/util/testsuite_performance.h
>index 556c78159be..8abc77cf31a 100644
>--- a/libstdc++-v3/testsuite/util/testsuite_performance.h
>+++ b/libstdc++-v3/testsuite/util/testsuite_performance.h
>@@ -167,7 +167,7 @@ namespace __gnu_test
>     {
>       if (getrusage(who, &rusage_begin) != 0 )
> 	memset(&rusage_begin, 0, sizeof(rusage_begin));
>-      malloc(0); // Needed for some implementations.
>+      void* p __attribute__((unused)) = malloc(0); // Needed for some implementations.
>       allocation_begin = mallinfo();
>     }
> 
>