Re: perf pmu: clang points out: address of array 'alias->unit' will always evaluate to 'true'

From: Jiri Olsa
Date: Wed Feb 15 2017 - 05:51:03 EST


On Tue, Feb 14, 2017 at 03:24:35PM -0300, Arnaldo Carvalho de Melo wrote:
> util/pmu.c:948:28: error: address of array 'alias->unit' will always evaluate to 'true' [-Werror,-Wpointer-bool-conversion]
> if ((info->unit && alias->unit) ||
> ~~ ~~~~~~~^~~~
> util/pmu.c:953:13: error: address of array 'alias->unit' will always evaluate to 'true' [-Werror,-Wpointer-bool-conversion]
> if (alias->unit)
> ~~ ~~~~~~~^~~~
> 2 errors generated.
>
>
> So, is this test about having something on that alias->unit array? I.e.
> should this suffice?

yep, that seems right.. good catch

thanks,
jirka

>
> [acme@jouet linux]$ cat clang.patch
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 82a654dec666..49bfee0e3d9e 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -945,12 +945,12 @@ static int check_info_data(struct perf_pmu_alias *alias,
> * define unit, scale and snapshot, fail
> * if there's more than one.
> */
> - if ((info->unit && alias->unit) ||
> + if ((info->unit && alias->unit[0]) ||
> (info->scale && alias->scale) ||
> (info->snapshot && alias->snapshot))
> return -EINVAL;
>
> - if (alias->unit)
> + if (alias->unit[0])
> info->unit = alias->unit;
>
> if (alias->scale)
> [acme@jouet linux]$