Merge C++ conversion into trunk (0/6 - Overview)

[Diego Novillo]

On 12-08-13 05:37 , Richard Guenther wrote:
> On Sun, Aug 12, 2012 at 10:04 PM, Diego Novillo <dnovillo@google.com> wrote:
>> I will be sending 6 patches that implement all the changes we
>> have been making on the cxx-conversion branch.  As described in
>> http://gcc.gnu.org/ml/gcc/2012-08/msg00015.html, these patches
>> change the default bootstrap process so that stage 1 always
>> builds with a C++ compiler.
>>
>> Other than the bootstrap change, the patches make no functional
>> changes to the compiler.  Everything should build as it does now
>> in trunk.
>>
>> I have split the merge in 6 main patches.  I will send these
>> patches to the respective maintainers and gcc-patches.
>> Please remember that the patches conform to the new C++ coding
>> guidelines (http://gcc.gnu.org/codingconventions.html#Cxx_Conventions):
>>
>> 1- Configuration changes.
>> 2- Re-write of VEC.
>> 3- Re-write of gengtype to support C++ templates and
>>     user-provided marking functions.
>> 4- New hash table class.
>> 5- Re-write double_int.
>> 6- Implement tree macros as inline functions so they can be
>>     called from gdb.
>>
>> As discussed before, several of these patches do not fully change
>> the call sites to use the new APIs.  We will do this change once
>> the branch has been merged into trunk.  Otherwise, the branch
>> becomes a maintenance nightmare (despite not having changed many
>> caller sites we were already starting to run into maintenance
>> problems).
>
> As I understand only 1. to 3. were kind-of required for the merge, all
> other changes are a bonus at this time and should be delayed IMHO
> (thus not merged with this batch).

Both #4 and #5 have the same issues as #3 (VEC).  What remains to be 
done is update a whole swath of user code.  This is hard to maintain in 
the branch and needs to be done during stage 1.  The change in #6 is 
similarly ready, so delaying it makes no sense.

What I can do is merge #1-#3 as one rev and merge the others as 3 
separate revisions.

> I also understand that you will, quickly after merging 1. to 3. convert
> all VEC users and remove the old interface.  This should be done
> before any of 4. - 6. is merged as generally we don't want the
> "half-converted" to persist, nor have multiple such half-conversions
> at the same time.

Yes, there will be no half conversions.  We are committed to continue 
making changes in this area.


Diego.