r173952 - [preprocessor] Don't warn about "disabled expansion of recursive macro"

[Argyrios Kyrtzidis]

On Jan 30, 2013, at 11:54 AM, Abramo Bagnara <abramo.bagnara at gmail.com> wrote:

> Il 30/01/2013 19:55, Argyrios Kyrtzidis ha scritto:
>> Author: akirtzidis
>> Date: Wed Jan 30 12:55:52 2013
>> New Revision: 173952
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=173952&view=rev
>> Log:
>> [preprocessor] Don't warn about "disabled expansion of recursive macro"
>> for "#define X X".
>> 
>> This is a pattern that, for example, stdbool.h uses.
>> rdar://12435773
> 
> Please revert this commit: this has already been discussed in detail in
> past and we decided otherwise. Last time it has been discussed in this
> thread:
> 
> http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20121029/067098.html

Reverted in r173970.

> 
>> 
>> Modified:
>>    cfe/trunk/lib/Lex/PPMacroExpansion.cpp
>>    cfe/trunk/test/Headers/stdbool.cpp
>>    cfe/trunk/test/Preprocessor/warn-disabled-macro-expansion.c
>> 
>> Modified: cfe/trunk/lib/Lex/PPMacroExpansion.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Lex/PPMacroExpansion.cpp?rev=173952&r1=173951&r2=173952&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Lex/PPMacroExpansion.cpp (original)
>> +++ cfe/trunk/lib/Lex/PPMacroExpansion.cpp Wed Jan 30 12:55:52 2013
>> @@ -459,7 +459,10 @@ bool Preprocessor::HandleMacroExpandedId
>>       if (MacroInfo *NewMI = getMacroInfo(NewII))
>>         if (!NewMI->isEnabled() || NewMI == MI) {
>>           Identifier.setFlag(Token::DisableExpand);
>> -          Diag(Identifier, diag::pp_disabled_macro_expansion);
>> +          // Don't warn for "#define X X" like "#define bool bool" from
>> +          // stdbool.h.
> 
> Would you be so kind to add a comment here to remember that the choice
> to have this warning for thar case (although disabled by default) is
> deliberate?

Just to make sure, are you of the opinion that we should warn when <stdbool.h> is included and its macros are used ?