Re: scary warning about casts

[Gregory Casamento]

Given that the cast is implicit this is left up to the compiler to determine.  Luckily GCC and clang (our only supported compilers) do this in the way we expect.  I suggest that we do a little better and do the conversion in a more predictable way so that we don't depend on undefined and/or compiler-specific behavior.  GC

On Fri, Nov 26, 2021 at 6:23 AM Riccardo Mottola <riccardo.mottola@libero.it> wrote:

Hello

I noticed I get these warnings, which look a bit scary.

 Compiling file XGServerWindow.m ...
XGServerWindow.m:3960:40: warning: implicit conversion from 'unsigned
int' to 'float' changes value from 4294967295 to
      4294967296 [-Wimplicit-int-float-conversion]
      opacity = (unsigned int)(alpha * 0xffffffffU);
                                     ~ ^~~~~~~~~~~
XGServerWindow.m:3996:31: warning: implicit conversion from 'unsigned
int' to 'float' changes value from 4294967295 to
      4294967296 [-Wimplicit-int-float-conversion]
        alpha = (float)*num / 0xffffffffU;


I think the warning is legit: alpha is float and is multiplied with an
explicit unsigned constant 0xffffffffU.

What is the code trying to achieve here?

Riccardo

--

Gregory Casamento
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