On Thu, 4 Nov 2010, Vasiliy Kulikov wrote:
> On Thu, Nov 04, 2010 at 17:06 +0100, Julia Lawall wrote:
> > On Thu, 4 Nov 2010, Vasiliy Kulikov wrote:
> > > IMO it should catch all C99 arrays, correct?
> >
> > I'm not an expert on what a C99 array is. But if it is the case where the
> > size is not a constant,
>
> Exactly.
>
> > then this looks fine.
> > I think you don't really
> > need TT. You could just say constant s, unless you need the type for
> > something else.
>
> Correct, thank you.
>
> > > Obviously 1+1 is constant :)
> >
> > I think this is something that has gone back and forth. Is it a big
> > problem in practice?
>
> Actually, I want to inspect all C99 array usages as they might be
> dangerous if array size is not correctly checked. If 1+1 is not
> constant, I would get just more code to manually check. It's not
> horrible, but I'd want to avoid it ;)
>
> Do you mean that to implement it properly you have to change too many
> boring cases of arithmetic operators? If so, don't trouble yourself.
No, I don't think it is hard to implement. I think that at some point I
didn't want that to be a constant, only "atomic constants". And then with
constant matching any expression that only involves constants, it
was hard to specify a pattern for atomic constants.
I guess I could have an atomic constant metavariable declaration? Or
maybe constexpression (like idexpression) for something that can also
match a more complex expression involving only constants?
Or if you find that some case such as + is common, then you could easily
add that into your ( | ), to cause it to be ignored. It would be
<+... E1 + E2 ...+>. If it doesn't parse, put parentheses around the
<+... ...+>.
> Also, defined constant is not constant too:
>
> --- main.c 2010-11-04 19:04:39.000000000 +0300
> +++ /tmp/cocci-output-16573-ef1775-main.c 2010-11-04
> 19:04:41.000000000 +0300
> @@ -11,9 +11,6 @@ main(int argc, char **argv)
> {
> int s = 2;
> int a[sizeof(int)];
> - int b[s];
> - int c[1+1];
> #define size 1
> - int d[size];
> return 0;
> }
Again, this could be viewed as a design decision, but it was one that I
didn't really think about. You should be able to add more to the ( | ) to
get rid of this problem as well.
julia
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