[cfe-commits] r64504 - in /cfe/trunk: include/clang/AST/ include/clang/Basic/ lib/AST/ lib/Analysis/ lib/CodeGen/ lib/Sema/ test/Analysis/ test/CodeGen/ test/Sema/

[Chris Lattner]

On Feb 14, 2009, at 11:32 AM, Daniel Dunbar wrote:

>>
>> I guess it is bad that we don't accept some programs we used to,  
>> but is this
>> really such a bad thing?  If this just affects stuff in llvm-test,  
>> I'm
>> inclined to just fix the programs.  If this occurs in some large C  
>> code
>> bases, then perhaps we should try to be more lenient.
>
> I'm just concerned about the number of such programs. It seems like
> there might be a good tradeoff in allowing some limited but common
> patterns of redefinition which are "safe", with the same diagnostic
> perhaps but as a warning. This would still put pressure on the user
> but at least allow the code to compile. This seems relatively easy for
> us to do, what is the downside?

The problem is that clients of the AST can't make the assumption that  
a builtin with a specified ID has the expected prototype.  GCC doesn't  
provide this guarantee so all sorts of code has to check that printf  
has at least 1 argument etc.  It is really annoying and leads to crash- 
on-invalid bugs.

I think the workaround of "build with -ffree-standing" is acceptable.

-Chris