Re: std:vec for classes with constructor? (Was: Re: [patch] multi-range implementation for value_range (irange))

[Andrew MacLeod <amacleod@redhat.com>]

On 8/24/20 5:53 PM, Jeff Law wrote:
> On Wed, 2020-08-05 at 17:41 +0200, Aldy Hernandez wrote:
>> On 8/5/20 5:09 PM, Martin Jambor wrote:
>>
>>> On Fri, Jul 31 2020, Aldy Hernandez via Gcc-patches wrote:
>>>
>>> [...]
>>>
>>>> * ipa-cp changes from vec<value_range> to std::vec<value_range>.
>>>>
>>>> We are using std::vec to ensure constructors are run, which they aren't
>>>> in our internal vec<> implementation.  Although we usually steer away
>>>> from using std::vec because of interactions with our GC system,
>>>> ipcp_param_lattices is only live within the pass and allocated with calloc.
>>>>
>>> Ummm... I did not object but I will save the URL of this message in the
>>> archive so that I can waive it in front of anyone complaining why I
>>> don't use our internal vec's in IPA data structures.
>>>
>>> But it actually raises a broader question: was this supposed to be an
>>> exception, allowed only not to complicate the irange patch further, or
>>> will this be generally accepted thing to do when someone wants to have a
>>> vector of constructed items?
>> I don't want to start a precedent without further discussion, so let's
>> assume this was an exception.
> I'd characterize it as an exception too.  When I looked at the patch for Aldy, I
> called out this code as well and asked him to justify it and convince me it was
> safe, which he did.  I'd to the same for anything else adding use of a standard
> C++ container to hold a GC-able object.
>
> I'd certainly like to get to a place where we could be using more standard C++
> library components.  But it'll take time to get there and consensus within the
> project.
>
> jeff
I think there were adjustments made to gcc's vec, and the usage of 
std::vector is no longer present..

I also think it was not a long term perfect solution, but adequate for 
our needs at the moment.

Personally, I have no issue with std::vector when approriate.. too bad 
we can make it adequate for all our usage  :-P  That is a much bigger 
issue I am afraid.

Andrew