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

[Will Dietz]

Ping! :)

~Will

On Mon, Nov 4, 2013 at 4:32 PM, Will Dietz <wdietz2 at illinois.edu> wrote:
> 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.