Re: Fwd: [glennrp/libpng] Apple clang 8.1.0 warnings (#156)

Yep, the original "Norcroft" ARM C compiler did this for a while, the
message was "warning no side effect in void context".  That was the 90's

Plus ca change, plus ca meme chose.

John Bowler

On Wed, Mar 29, 2017 at 11:02 AM, Glenn Randers-Pehrson <[email protected]>
wrote:

> New libpng warnings.  I don't know why clang is objecting to
> what seems to be valid use of the comma.  The warning messages
> hint that using "(void)" would suppress the warnings.
>
> I suspect that in most cases the warning could also be suppressed
> by using semicolons instead of commas, and adding braces
> if necessary, as in
>
>      if (test <= DBL_MAX)
>               {
>                  ++exp_b10; base=test;
>               }
>
> in place of
>
>      if (test <= DBL_MAX)
>                ++exp_b10, base = test;
>
> Glenn
>
> ---------- Forwarded message ----------
> From: Viktor Szakats <notifications-9UaJU3cA/F/[email protected]>
> Date: Wed, Mar 29, 2017 at 5:56 AM
> Subject: [glennrp/libpng] Apple clang 8.1.0 warnings (#156)
> To: glennrp/libpng <[email protected]>
> Cc: Subscribed <[email protected]>
>
>
> After this week's toolchain updates, the following, mostly -Wcomma
> warnings appeared. Also included some existing const stripping warnings.
> This is so when building libpng with -Weverything option, I haven't
> tested with other warning levels. Anyhow some of these *may* be useful
> information.
>
> png.c:2835:16: warning: possible misuse of comma operator here [-Wcomma]
>       recip = 1, power = -power;
>                ^
> png.c:2835:7: note: cast expression to void to silence warning
>       recip = 1, power = -power;
>       ^~~~~~~~~
>       (void)(  )
> png.c:2913:25: warning: possible misuse of comma operator here [-Wcomma]
>                ++exp_b10, base = test;
>                         ^
> png.c:2913:16: note: cast expression to void to silence warning
>                ++exp_b10, base = test;
>                ^~~~~~~~~
>                (void)(  )
>
> [snip]
>
>
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-- 
John Bowler <[email protected]>
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