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Re: [PATCH][C] Change array size overflow check
On Mon, 2 May 2011, Richard Guenther wrote:
> We do have similar testcases in gcc.dg/large-size-array*.c, but not
> exactly testing the bound. The above testcase also complains with
> -pedantic about
>
> t.c:3:13: error: size of array 'a' is too large
> t.c:4:1: error: overflow in constant expression [-Woverflow]
> t.c:5:12: error: size of array 'c' is too large
> t.c:6:1: error: overflow in constant expression [-Woverflow]
>
> with and without the patch. I can add -Wno-overflow to the flags.
> Ok with that?
Those overflow errors are bugs (the tests have no overflowing constant
expression, it must be something the compiler is generating internally),
and it seems they only appear for 64-bit compilation for me, not for
32-bit, for some reason. But as they are independent of the patch, OK
with -Wno-overflow and with a PR filed for the bogus overflow errors.
(I get the overflow errors for a char array for a size of
((size_t)-1 >> 4)+1 but not for ((size_t)-1 >> 4), i.e. 1ULL<<60 bytes is
the point where the bogus errors start.)
--
Joseph S. Myers
joseph@codesourcery.com