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Re: [Cygwin-ports-general] Ncview


On Thu, 2015-10-01 at 23:35 +0200, Marco Atzeri wrote:
> On 01/10/2015 19:35, Yaakov Selkowitz wrote:
> > On Mon, 2015-09-28 at 17:33 +0200, Marco Atzeri wrote:
> >> On 28/09/2015 16:07, Vasileios Anagnostopoulos wrote:
> 
> >>
> >> 2) the 64 bit crashes inside X libs.
> >>      I never succeeded to identify the root cause
> >
> > Confirmed.  Often 64-bit-only issues come down to one or more of the
> > following:
> >
> > * implicit function declarations.  Per the C standard, argument types
> > are assumed to match whatever is given (which may be wrong if e.g. 0 is
> > used instead of 0L or (PointerType)0 or NULL etc.) and the return type
> > is assumed to be int (which will truncate the actual return value when
> > it is actually a long/pointer).
> 
> This is not. The only two implicit declaration are of type int
> and declaring them changes noting.
> 
> >
> > * vararg types.  Because these types aren't declared, the compiler can't
> > automatically cast values to the correct type, so literal values and
> > symbolic constants must be explicitly cast if they are not meant to be
> > an int and are not obviously a long/pointer.
> 
> I don't find any case.

The XtVa* functions use varargs.

> > In the case of ncview, I strongly suspect the latter should anyone be
> > interested in fixing this.
> 
> The hard issue is that only cygwin 64 bit seems impacted,
> while other 64 platform are fine,
> and that the crash is well deep X libraries during the
> destruction phase of graphical elements
> as the X graphics elements are not correctly destroyed in sequence.
> 
> If someone more knowledgeable in X is interested I can provide the 
> program and a test case.

That would be great.

--
Yaakov




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