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!
fix_smallvector.patch (929 Bytes)
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.
Well, assuming that SmallVector should be as similar to std::vector as
possible, and looking at n3290 23.2.3/{8,9}:
8 The iterator returned from a.insert(p, n, t) points to the copy of
the first element inserted into a, or p if n == 0.
9 The iterator returned from a.insert(p, i, j) points to the copy of
the first element inserted into a, or p if i == j.
The answer is rather clear.
- Michael Spencer