Re: [RFC PATCH 1/2] audio/mixeng: Fix Clang 'int-conversion' warning

[BALATON Zoltan <balaton@eik.bme.hu>]

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On Sun, 3 May 2020, Philippe Mathieu-Daudé wrote:
> When building with Clang 10 on Fedora 32, we get:
>
>    CC      audio/mixeng.o
>  audio/mixeng.c:274:34: error: implicit conversion from 'unsigned int' to 'float' changes value from 4294967295 to 4294967296 [-Werror,-Wimplicit-int-float-conversion]
>  static const float float_scale = UINT_MAX / 2.f;
>                                   ^~~~~~~~ ~
>  /usr/lib64/clang/10.0.0/include/limits.h:56:37: note: expanded from macro 'UINT_MAX'
>  #define UINT_MAX  (__INT_MAX__  *2U +1U)
>                     ~~~~~~~~~~~~~~~~~^~~
>
> Fix by using a 64-bit float for the conversion, before casting
> back to 32-bit float.
>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
> audio/mixeng.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/audio/mixeng.c b/audio/mixeng.c
> index 739a500449..9946bfeaec 100644
> --- a/audio/mixeng.c
> +++ b/audio/mixeng.c
> @@ -271,7 +271,7 @@ f_sample *mixeng_clip[2][2][2][3] = {
> #define CONV_NATURAL_FLOAT(x) (x)
> #define CLIP_NATURAL_FLOAT(x) (x)
> #else
> -static const float float_scale = UINT_MAX / 2.f;
> +static const float float_scale = UINT_MAX / 2.;

Maybe writing it as 2.0 is easier to read and looks nicer.

Regards,
BALATON Zoltan