[PATCH] ASTVector: Fix return value of various insert() methods

[Will Dietz]

Ping.

It's easy to get clang to trigger this bug which results in an invalid
iterator to be returned (which the current code happens to ignore, but
that's just a lucky coincidence), as this regularly occurs during
execution of the lit tests.

On a related note, any suggestions on how to create a simple dummy
ASTContext for testing? As noted in
the commit that originally added ASTVectorTest.cpp (r186253) this
blocks the creation of even basic
functionality tests for this data structure.

~Will

On Mon, Oct 28, 2013 at 5:11 PM, Will Dietz <wdietz2 at illinois.edu> wrote:
> Error caught -fsanitize=pointer-overflow[1], curiously enough :).
>
> The pointer overflow occurred when insert() was invoked with From==To,
> which is done in quite a few places.  While std::vector::insert
> requires [From,To) to be valid, it looks like here From==To is
> intended to be supported[2], making the bug in the container not in
> its use.
>
> This patch fixes the overflow when From==To, as well as the return
> value in this variant as well as the "fill" variant, changing them to
> return an iterator pointing to the first of the inserted elements
> (like SmallVector does).
>
> See attached.
>
> ~Will
>
> [1] Patches coming soon.
> [2] See the implementation of append(), for example.