[llvm-commits] [llvm] r160854 - /llvm/trunk/include/llvm/ADT/SmallVector.h

[Chandler Carruth]

On Fri, Jul 27, 2012 at 2:10 AM, Benjamin Kramer
<benny.kra at googlemail.com>wrote:

> Author: d0k
> Date: Fri Jul 27 04:10:25 2012
> New Revision: 160854
>
> URL: http://llvm.org/viewvc/llvm-project?rev=160854&view=rev
> Log:
> SmallVector::erase: Assert that iterators are actually inside the vector.
>
> The rationale here is that it's hard to write loops containing vector
> erases and
> it only shows up if the vector contains non-trivial objects leading to
> crashes
> when forming them out of garbage memory.
>
> Modified:
>     llvm/trunk/include/llvm/ADT/SmallVector.h
>
> Modified: llvm/trunk/include/llvm/ADT/SmallVector.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/SmallVector.h?rev=160854&r1=160853&r2=160854&view=diff
>
> ==============================================================================
> --- llvm/trunk/include/llvm/ADT/SmallVector.h (original)
> +++ llvm/trunk/include/llvm/ADT/SmallVector.h Fri Jul 27 04:10:25 2012
> @@ -463,6 +463,7 @@
>    }
>
>    iterator erase(iterator I) {
> +    assert(I >= this->begin() && I < this->end() && "Iterator out of
> bounds");
>

What do you think about making these separate asserts so that the line
number (and message) tell you exactly what went wrong instead of just that
something went wrong? It's a bit more code, but not that much...

Also, is it worth factoring these asserts into a generic pair of functions,
one to validate a single iterator, one to validate a begin/end pair, and
use them more consistently throughout APIs that accept such iterators?

     iterator N = I;
>      // Shift all elts down one.
>      this->move(I+1, this->end(), I);
> @@ -472,6 +473,8 @@
>    }
>
>    iterator erase(iterator S, iterator E) {
> +    assert(S >= this->begin() && S <= E && E <= this->end() &&
> +           "Iterator range out of bounds");
>      iterator N = S;
>      // Shift all elts down.
>      iterator I = this->move(E, this->end(), S);
>
>
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