-Warray-bounds false positive when a cast is involved

[seanm]

Bugzilla Link	10771
Resolution	FIXED
Resolved on	Sep 22, 2011 09:50
Version	trunk
OS	All
CC	@DougGregor,@belkadan,@tkremenek,@nico

Extended Description

Consider this C++:

int main (void)
{
double foo[4096];
((char *)(foo))[(sizeof(foo)-1)] = '\0';

return 0;

}

It outputs:

test.cp:4:12: warning: array index of '32767' indexes past the end of an array (that contains 4096 elements) [-Warray-bounds]
((char *)(foo))[(sizeof(foo)-1)] = '\0';
^ ~~~~~~~~~~~~~

It's a false positive. Note the cast to char*.

This is with clang version 3.0 (trunk 138577).

[efriedma-quic]

*** Bug llvm/llvm-bugzilla-archive#10937 has been marked as a duplicate of this bug. ***

[nico]

This happens e.g. in ICU

[seanm]

In my case, the original code in question is from the open source ITK project. The warning can be seen on its nightly dashboard:

http://www.cdash.org/CDash/viewBuildError.php?type=1&buildid=1533029

[nico]

r139990

[seanm]

Confirmed fixed.

[efriedma-quic]

mentioned in issue llvm/llvm-bugzilla-archive#10937

[llvmbot]

mentioned in issue llvm/llvm-bugzilla-archive#44343