Re: [boost] Clang: Open-source C/C++ front end under development

From: David Greene (greened_at_[hidden])
Date: 2007-09-02 15:04:04

David Abrahams wrote:

>> Again, this does not mean that we avoid templates, and it doesn't  
>> mean we have no templated interfaces :).  
> 
> Oh, I got a different impression from earlier messages in this thread.

What Chris says is true.  My message was more to the point of seeing if
Boost could provide solutions for common problems in llvm.  When I
brought this up on the llvm list, the feedback was rather strongly
negative.  My goal here is not to force anything on llvm.  Rather, it's
to improve the Boost community's ability to clearly articulate the
tradeoffs involved in using Boost.  Now, in my own experience these
tradeoffs have almost always been a win and I believe there are places
in llvm where they could be a win as well.

Mathias brings up reasonable questions as to the pointer-based
interface.  It's true that llvm has had more problems with iterators
(in fact, I discovered many of them).  I believe this is due to a
combination of relative inexperience with the standard library but also
some inconsistency in how the standard library's proponents present
their case.

BUT, those problems were easily found BECAUSE the iterator interface
is well-encapsulated in a way that allows injection of bug-checking
code.

BTW, the specific issue that keeps coming up involves taking the address
of the first element of an empty std::vector:

&a[0];

The C++ community promotes std::vector as a C array replacement, but
it's really not because it's not legal to do the above operation when
the vector is empty.  I believe this is because the vector interface
is characterized in terms of iterators rather than addresses.  Thus
operator[] implies operator* even though the address of the result is
all that's desired.

                                -Dave