[LLVMdev] [Patch] Fix bug in llvm::SmallVectorIml<>::insert

[Johannes Schaub (litb)]

Johannes Schaub (litb) wrote:

> This fixes a bug in SmallVectorImpl<>::insert, which were not behaving
> correctly on inserting an empty range into an empty vector:
> 
> #include <llvm/ADT/SmallVector.h>
> #include <cassert>
> 
> int main() {
>   llvm::SmallVector<int, 1> v, w;
>   llvm::SmallVector<int, 1>::iterator it =
>     v.insert(v.end(), w.begin(), w.end());
>   assert(it == v.end());
> }
> 
> The insert function(s) would incorrectly return "this->end()-1". I
> attached the patch which I diff'ed from trunk. Is it important enough to
> be backported to llvm2.9 ?
> 
> I would like to ask someone to commit it to wherever it fits. Thanks!

Hmm, I don't understand the rationale of the return value of the range-
insert and repeated-insert.

The range-insert returns an iterator pointing exactly at the last value 
inserted. 

But the repeated-insert (i.e Insert(Position, RepeatCount, Value)) 
apparently returns an iterator pointing to the first value inserted. Is this 
actually intended?

My patch is inconsistent with this in mind, because it always returns a 
pointer to the first value inserted. Please don't apply it yet. We need to 
clear this up first and fix my patch.