Unified front end for C and C++ (was Re: New C parser [patch])

[Matt Austern <austern@apple.com>]

On Oct 25, 2004, at 4:42 PM, Scott Robert Ladd wrote:

> Ziemowit Laski wrote:
>> While I don't buy these time estimates (not both simultaneously, 
>> anyway), I do
>> agree that you would take a performance hit, at least in the 
>> short-term,
>> especially for plain C code.
>
> I don't think this is a hit GCC's users can afford at this point. 
> Another compile time regression may bring the hordes with pitchforks 
> and torches... ;)
>
> Also, C and C++ are heading down different and incompatible paths. It 
> will be increasingly difficult to manage the subtle-but-important 
> differences in a single front end if the two languages continue to 
> diverge.

On the one hand, that sounds plausible.  On the other hand: gcc is the 
only compiler I know of that has separate source bases for the C and 
C++ front ends.  Certainly EDG, MetroWerks, and Microsoft use the same 
source base for both, and at least one of those three uses not only the 
same source base but the same executable.

It may very well be true that getting from where we are to a common 
front end for C and C++ would be so hard that it's not worth doing.  
But we do have an existence proof that such a compiler is possible and 
that it's can be maintainable and fast.

(Changing the subject line because this no longer has much to do with 
Joseph's patch.)

			--Matt