[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 Sun, Feb 15, 2009 at 10:06 AM, Douglas Gregor <dgregor at apple.com> wrote:
>
> On Feb 14, 2009, at 8:19 PM, Daniel Dunbar wrote:
>
>> On Sat, Feb 14, 2009 at 5:43 PM, Chris Lattner <clattner at apple.com> wrote:
>>>
>>> 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.
>>
>> Sorry, I guess I wasn't clear.
>>
>> I wasn't saying we should allow the invalid prototype. I think we
>> should just treat it as a warning instead of an error in some cases
>> (maybe even all), and the effect will be that we just ignore the
>> declaration in the code. I'm certainly not proposing we create
>> ill-formed AST nodes.
>
> What if the invalid declaration is also a definition? Do we just skip over
> the entire body?

I would say, in that case reject it and mention that the user may want
-ffreestanding.

 - Daniel