-Warray-bounds false positive?

Clang Frontend
1

Hi all,

I'm not enough of a language lawyer to be 100% sure, but:

2

Yes. File a bug? :slight_smile:

3

No, the warning is legit. sizeof() returns the size in bytes, not elements. This is an array of doubles.

4

But it's been casted to char *. This is equivalent to this code:

double foo[4096];
char *bar = (char *)foo;
bar[sizeof(foo)-1] = '\0';

I mean, it's probably a bad idea, but it's not an out-of-bounds error.

5

Ah, you're right. We should adjust the array size in the warning based on the pointer type being accessed.

6

Jordy et al,

The check should be accounting for the array being cast to char*… not sure why it isn’t (and in the middle of trying to refactor ActOnFunctionDeclarator). When the bug is filed you can assign it it me, as I’ve already done a lot of work on improving -Warray-bounds and would like to know/dig into why the false positive is triggering.

Cheers,
Kaelyn

7

Thanks for making me not the only one to be momentarily confused! :slight_smile:

I filed:
<http://llvm.org/bugs/show_bug.cgi?id=10771&gt;

Cheers,