[PATCH] gdi32: Declare our intent explicitly to the compiler.

[Michael Stefaniuc]

On 02/17/2016 04:04 PM, Ken Thomases wrote:
> On Feb 17, 2016, at 4:12 AM, Michael Stefaniuc <mstefani at redhat.com> wrote:
>>
>> On 02/17/2016 10:27 AM, Charles Davis wrote:
>>> Clang warns about this abs(3) call because the argument is of
>>> unsigned type. Apparently, though, this is actually a signed value
>>> that just happens to be stored in a DWORD. (Then why is this
>>> parameter to ExtCreatePen() a DWORD?)
>>>
>>> In any case, quiesce this warning with a cast.
>> Well, clang is wrong here. abs() takes a signed integer and the
>> implicit cast from unsigned to signed is perfectly valid C.
> 
> Warnings are not for calling out things that are invalid — that's what
There is a lot of undefined behavior for which the compilers don't
output any errors or warnings. With valid C I meant well defined C.

> errors are for — they're for calling out things that may be
> unintentional or confusing.  I think this qualifies.  It's fairly
> non-obvious that this DWORD value should be treated as signed, as
> evidenced by Chip's initial approach of just removing the abs() call.
No, he just removed it because clang complained, probably with a
misleading warning. Doubt he would have done it on a code review.
Because the abs() call as it is looks perfectly normal and does the
right thing.

By adding the cast he just added a big red blinking "Warning there might
be dragons". And there are no dragons, just a normal implicit unsigned
to signed cast. No need to drag attention to it.
In an ideal world one would fix the type of that parameter but we don't
have that freedom in Wine.

> Something is needed to clarify the intent of the code.
IMHO the intend of the code was clearer without the cast.
But I guess this falls into "the matter of taste" category and Alexandre
will apply it as Huw signed off on it.

bye
	michael