Re: [PATCH 14/14] libfdt: fdt_strerror(): Fix comparison warning

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

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On Mon, Sep 21, 2020 at 05:53:03PM +0100, Andre Przywara wrote:
> With -Wsign-compare, compilers warn about a mismatching signedness
> in a comparison in fdt_strerror().
> 
> At this point we are sure that errval is negative, and since
> FDT_ERRTABSIZE is surely positive, we can do some casting to make the
> compiler happy.
> 
> Signed-off-by: Andre Przywara <andre.przywara-5wv7dgnIgG8@public.gmane.org>

Since error values are typically conveyed as negative numbers (which
is kind of the whole reason we have all these signed values in the
first place), I think it would be slightly nicer to actually fold the
case to signed into the definition of FDT_ERRTABSIZE.

> ---
>  libfdt/fdt_strerror.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libfdt/fdt_strerror.c b/libfdt/fdt_strerror.c
> index 768db66..efce51d 100644
> --- a/libfdt/fdt_strerror.c
> +++ b/libfdt/fdt_strerror.c
> @@ -48,7 +48,7 @@ const char *fdt_strerror(int errval)
>  		return "<valid offset/length>";
>  	else if (errval == 0)
>  		return "<no error>";
> -	else if (errval > -FDT_ERRTABSIZE) {
> +	else if (errval > -(int)FDT_ERRTABSIZE) {
>  		const char *s = fdt_errtable[-errval].str;
>  
>  		if (s)

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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