[cfe-dev] Clang comparison page

[Chris Lattner]

On Dec 9, 2007, at 9:27 PM, Joel Nelson wrote:

> I have no stake in Elsa, and I've never used it,

Your opinion is welcome!  I've made some edits in response to your  
feedback:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20071210/003255.html

> but my thoughts:
>
> Elsa is not a compiler, so I'm not sure that the following point is  
> appropriate:
>
> "Elsa does not support native code generation."

Right.  This gets to the "differences in goals" aspect of the  
comparison.  I should mention explicitly at the top that whether you  
consider one of these to be a big deal depends on what your personal  
goals are.  I clarified this in the intro.

> Also the following point seems to be a political (and practical,
> granted) rather than a technical criticism:
>
> "The Elsa community is extremely small and major development work
> seems to have ceased in 2005, though it continues to be used by other
> projects (e.g. Oink). Clang has a vibrant community including
> developers that are paid to work on it full time."
>
> A small community is only a problem for those who do not have the
> resources to contribute to the project themselves.

I mention this because it is a very big disadvantage for a lot of  
people: it basically means that if you hit a bug in Elsa, you have to  
fix it yourself or just work around it.  In clang, you can report the  
bug and it quite possible someone will fix it for you.  This means  
that even if you *could* fix the bug yourself, you might find out that  
you don't have to, meaning you get more done in less of *your* time.

> Since as you say
> Clang has plenty of resources,

There is no such thing as "plenty" :)

> 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.

I updated the bullet to try to make it more clear what I'm getting at,  
please take a look and let me know if it helps.

> 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?

-Chris