[cfe-dev] On the preferred use of C++ in the clang source code

[James Widman]

On Nov 9, 2007, at 12:07 PM, Chris Lattner wrote:

>
> On Nov 9, 2007, at 8:55 AM, James Widman wrote:
>
>> I've heard that clang is meant to be implemented in a "subset of C+
>> +" (which I guess means that some core language features are barred
>> from use).
>>
>> Is there a document anywhere that describes and motivates that  
>> subset?
>
> It is pretty subjective.  We do use almost all C++ features  
> somewhere in the (greater llvm) code base.  It's really more about  
> making clear and simple code than it is about banning specific  
> language features.  Some coding guidelines are available here:
> http://llvm.org/docs/CodingStandards.html

Bookmarked; thanks!

Note, the reference to "Effective C++" at the bottom is a little out  
of date; the third edition was published two years ago and contains  
some significant changes:

http://tinyurl.com/26gch4

Also the other two links (for the strings "available as well" and  
"Large-Scale C++ Software Design" appear to be broken.

> That said, there are two features we don't like:  RTTI and EH.   
> This is because they violate the "don't pay for it if you don't use  
> it" principle.  If building with GCC, clang disables both RTTI and  
> EH support (-fno-rtti and -fno-exceptions).  The main llvm  
> repository has a couple of places that still use RTTI, but we'd  
> like to fix that.
>
> The main problem with RTTI and EH is the impact on binary size.   
> Many clients of LLVM and at least one client of clang use them in a  
> JIT context.  Having the binaries be as small as possible makes it  
> easier for people to distribute them with their apps.

I think that may be the least-flaky objection to EH that I've heard  
so far.  (:

I'll have to meditate on it.

Thanks again!

James Widman
-- 
Gimpel Software
http://gimpel.com