[cfe-dev] Fwd: Clang comparison page

[Chris Lattner]

>>> then I think Elsa could be adopted as
>>> the C++ parser if there were no technical issues, or if the cost of
>>> resolving the technical issues was less than the cost of a
>>> reimplementation.
>>
>> If a reader has the ability to reimplement an entire C++ compiler  
>> from scratch and has the desire to do so, presumably they wouldn't  
>> be looking at either clang or elsa :).  The rest of the bullets  
>> explain technical problems that prevent clang from adopting Elsa.
>
> The only reason someone would be comparing Elsa and Clang today  
> would be if they are interested in helping to implement a c++  
> parser themselves in clang (as you basically said).

No, I don't think that is the case.  I think it's fair to say that  
people looking at elsa and clang are doing so because they *don't*  
want to implement a C++ parser, they just want to use one.  The goal  
of the comparison is to make it possible for someone with a specific  
application goal (e.g. "build a refactoring tool for C") to decide  
whether clang is a good match for their goals.

>>> I just thought these two points may be unfair given the scope of  
>>> this
>>> doc is stated as "We restrict the discussion to very specific
>>> technical points to avoid controversy where possible." Maybe its  
>>> this
>>> statement which should be changed, instead.
>>
>> I think it is true that the Elsa community is "extremely small",  
>> do you disagree with that part?
>>
> No I think you are completely correct. I just wouldn't call that a  
> technical point.

Fair enough.  I changed the intro to be a bit more clear about what  
we're comparing, hopefully this make sense:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of- 
Mon-20071210/003263.html

> That may be the *result* of technical weaknesses (as you argue  
> well), or it could be the result of a lack of the kind of promotion  
> you do for clang. Either way I think it is not itself material.   
> Basically I think Clang can win on technical merits, so why not  
> leave it at that?

As Steve mentioned, this is about communication, not "winning".  The  
comparison makes it very clear that if one needs C++ support in the  
immediate future, Elsa *is* a better solution than clang.

I strongly believe that community is an important issue for many  
groups who are "shopping around" for a compiler front-end to use.  In  
academic research, for example, people are often under tight  
deadlines and want to focus their limited time and energy on getting  
their research goals accomplished.  Few people in academia are given  
the opportunity to do a significant amount of infrastructure work.   
Having a solid base to build on and having a community willing to  
help fix bugs and answer questions is extremely valuable to these  
(and many other) people.

-Chris