Re: [PATCH][RFC] -Wno-... option to suppress builtin macro redefined warnings

[Simon Baldwin <simonb@google.com>]

Simon Baldwin wrote:
> Simon Baldwin wrote:
>> Tom Tromey wrote:
>>>>>>>> "Simon" == Simon Baldwin <simonb@google.com> writes:
>>>>>>>>             
>>>
>>> ...
>>> However, it seems to me that we would want to allow redefinition of
>>> some macros (__TIME__ et al) but not others (e.g., __LINE__).
>>>
>>> So, how about splitting builtin_array into two pieces (and just FYI,
>>> there's a comment above referring to "two tables" that should be
>>> changed) and then unconditionally setting NODE_WARN for one table but
>>> not the other?  Or, just adding a special case in the builtin
>>> definition loop for the BT_* constants we care to allow.
>>>   
>>
>> Thank you for the note.
>>
>> I guess that in general it just seems more, um, seamless to either 
>> allow or disallow any builtin macro to be redefined.  It means that 
>> there's no "is it redefinable or not?" decision to be made when new 
>> builtins are added.  It also neatly sidesteps the issue of then 
>> having to document which builtins are redefinable and which aren't 
>> (also no update to this doc should new builtins be added), or having 
>> to deal with requests to move builtins between redefinable/fixed 
>> groups.  In other words, the lowest impact on future code maintainers 
>> consistent with low impact on current code.
>>
>> Granted, somebody could well redefine __LINE__ or similar and make a 
>> mess of compilation, but there are of course plenty of other ways to 
>> make a mess of compilation with other gcc flags.  
>> -Wno-builtin-macro-redefined is aimed at the control-freak automated 
>> build system rather than the casual user, so it seemed okay, to me 
>> anyway, for it to bear closer resemblance to a chainsaw than to a 
>> scalpel.
>>
>> That said, I'm not wildly opposed to creating two "classes" of 
>> builtin.  It just seems like doing so might sow slightly more 
>> confusion than it prevents.
>
> Tom, any further thoughts on this?
>
> It's certainly not hard to split built-in macros into two tiers, those 
> where redefinition warning can be suppressed by providing 
> -Wno-builtin-macro-redefined, and those where it can't.  However, 
> since it's all just about suppressing a warning, it may be that one 
> policy to cover all of them will suffice, and be simpler to manage and 
> maintain.
>
> Thanks.
>


No response from Tom to date.

Would anyone else be prepared to pick this up in the interim?  Thanks.

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