[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/

[Daniel Dunbar]

On Fri, Feb 13, 2009 at 7:33 PM, Chris Lattner <clattner at apple.com> wrote:
>
> On Feb 13, 2009, at 7:10 PM, Daniel Dunbar wrote:
>
>> Nice, very very nice.
>>
>> Unfortunately, this is also causing us to reject quite a few of the
>> applications in the LLVM test-suite. I haven't had time to diagnose
>> the exact issues, but I think we are going to need to be more
>> accepting of other definitions of builtins. For example:
>> --
>> char *malloc();
>> void *f0() { return malloc(4); }
>> --
>>
>> Can you take a look?
>
> It's not clear to me that we should do this.  Before the patch, we would
> have code that "worked with with GCC" get silently miscompiled with clang.

Well, the given snippet wouldn't actually get silently miscompiled.

>  Now we have code that "works fine with gcc" get "summarily rejected by
> clang".  This is a big step forward in some ways.

Agreed!

> 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?

 - Daniel

>
> -Chris
>
>>
>>
>> - Daniel
>>
>> On Fri, Feb 13, 2009 at 3:52 PM, Chris Lattner <clattner at apple.com> wrote:
>>>
>>> On Feb 13, 2009, at 3:20 PM, Douglas Gregor wrote:
>>>
>>>> Author: dgregor
>>>> Date: Fri Feb 13 17:20:09 2009
>>>> New Revision: 64504
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=64504&view=rev
>>>> Log:
>>>> Implicitly declare certain C library functions (malloc, strcpy,
>>>> memmove,
>>>> etc.) when we perform name lookup on them. This ensures that we
>>>> produce the correct signature for these functions, which has two
>>>> practical impacts:
>>>
>>> Nice!!
>>>
>>> -Chris
>>>
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