Hi,

On Sun, 26 Jul 2015 12:34:22 -0700
Konstantin Serebryany <[email protected]> wrote:

> First, is that clang or gcc, and which version?
> Second, is that C or C++?

C, both gcc and clang, no difference.

> If this is C, try adding -fno-common (in C, some of the globals are
> not instrumented with asan unless you use -fno-common).

Okay, with -fno-common I get an error. That's interesting to know, it
sounds like -fno-common is a useful addition to asan when trying to find
bugs.

> Finally, artificial tests like this are often misleading because the
> compiler statically sees the bug and should warn about it,
> but also can optimize the code away before asan has a chance to
> instrument the code.
> Try to prepare a test where the bug is not easy to discover
> statically.

That's actually also interesting. clang will warn about this bug
compile-time, gcc won't. Seems gcc doesn't have any checks for static
out of bounds access at all.
However a small change, using something like int b;int c=a[b]; will
already beat the clang warning and the behavior will be the same.


cu,
-- 
Hanno Böck
http://hboeck.de/

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