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Re: Module with preprocessor utilities


From: Marc Nieper-Wißkirchen
Subject: Re: Module with preprocessor utilities
Date: Fri, 24 Jul 2020 10:33:08 +0200

Am Fr., 24. Juli 2020 um 10:05 Uhr schrieb Florian Weimer <fweimer@redhat.com>:

> It's still a candidate for an RFE.  Martin Sebor has been working on
> such warnings.  I'm going to talk to him.

It may also be useful for optimizations because the compiler may make
assumptions.

> >> It's also undefined when you pass the address of something that is not
> >> the first element of an array of type double to foo1.  (Undefined in the
> >> sense that the standard does not say what happens in that case.)
> >
> > Yes, but a pointer to (an existing) double fulfills this requirement.
>
> I don't think that's how the standard defines “first element of an
> array”.  I suspect the intent was that it the pointer has to point to an
> array of at least the indicated number of elements, but that's not what
> the standard says.

According to ISO C, "an array type describes a contiguously allocated
nonempty set of objects with a particular member object type, called
the element type". Thus, given

double x;
double *p = &x;

the pointer p points to the first element of an array (of length 1).

Maybe I have misunderstood you.

Thanks,

Marc



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