Re: Using C++ in GCC is OK

[Mark Mitchell <mark at codesourcery dot com>]

Basile Starynkevitch wrote:

> Except that perhaps these questions are important for any gengtype
> enhancement. In particular, one could consider that marking a GTY-ed
> data would be done by a virtual method (generated by gengtype), and then
> having every GTY-ed data inheriting from an abstract class providing
> this method will make both gengtype & ggc*.c simpler.

There is no pressing need for a gengtype enhancement as far as I can
tell.  I think the right way to look at this is that we can now use C++
going-forward to implement things, and that is helpful.  In some cases,
we'll want to convert existing things to C++ because that helps us to do
new things.  But, we don't need to convert things just because we can.
We don't get a prize for having a tidier code base *in and of itself*.

I think we should focus on some user-visible deliverable (better
optimization, faster compiler, new language feature, plugin API,
whatever).  If converting something to use C++ helps achieve that goal,
great.  If it doesn't, then why bother?

I'm not saying that we should reject "clean-up" patches that use C++ in
some way that makes things notably tidier.  I'm just saying that I'm
more excited if I see how that patch is going to help us build new
functionality.  And, I think it's premature to start talking about
particular changes to particular parts of the compiler.

Step 1 is to agree on the subset of C++ we're willing to use.  Step 2 is
for someone to propose a C++-using patch that does something useful and
get it approved.  So far, I've seen a lot of input on Step 1, but nobody
that wants to step up and take responsibility for the task.  Any takers?

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713