Addendum:
> > > - 'restrict' should NOT be used for multiple output parameters of the
> > > same type, when only a single word is written through each parameter.
> > > Example: ssize_t copy_file_range (int ifd, off_t *ipos, int ofd,
> > > off_t *opos,
> > > size_t len, unsigned flags);
> > > Rationale: It is OK to have ipos and opos point to different elements
> > > of the same off_t[] array.
> >
> > Ouch, this is exactly the opposite of what I would have wanted, since I
> > want
> > 'restrict' to tell the caller "these should not be aliases" and I want that
> > to
> > be true for *IPOS and *OPOS. (I'm not sure what is meant by 'single word'
> > here;
> > surely it shouldn't matter whether the type is a struct....) Could you
> > explain
> > more where the 'same array' rule comes from?
>
> The "same array" rule comes from what I understood from various explanations
> of 'restrict' on the web [1], and from what I see in the glibc headers for
> functions that have multiple output parameters of the same type
Also, I thought that passing pointers to different elements of the same array
would produce warnings. But I was mistaken: This code does NOT produce warnings.
================================================================================
#include <stddef.h>
extern int copy_file_range (int, long *restrict, int, long *restrict, size_t,
unsigned int);
int infd;
int outfd;
long offsets[2];
int copy_block (void)
{
return copy_file_range (infd, &offsets[0], outfd, &offsets[1], 4096, 0);
}
================================================================================
Bruno
