Re: nullptr vs 0

From: Bo Persson (bo_at_[hidden])
Date: 2022-05-23 06:53:18

On 2022-05-22 at 23:58, Andrey Semashev via Boost wrote:
> On 5/22/22 18:35, Peter Dimov wrote:
>>> I did however not know that GCC doesn't warn on NULL. Interesting
>>> compromise, even though I don't quite see the point of it.
>>>
>>> Clang does warn on NULL, however.
>>
>> I do see the point of it now. Under GCC the warning is pragmatically
>> intended to catch actual mistakes such as mistyping
>>
>>      while( *p != 0 )
>>
>> as
>>
>>      while( p != 0 )
>>
>> so the warning only triggers on the actual 0, and is enabled under
>> C++03 as well.
>>
>> Clang, and the various static analysis tools such as the MS analyzer,
>> enforce a stylistic preference for nullptr, so they warn on both 0
>> and NULL, but Clang doesn't warn in C++03 mode.
>>
>> Either way, I'm not looking forward to adding a bunch of lines to
>> suppress the various warnings, instead of just telling the PR author
>> to use BOOST_NULLPTR instead of nullptr.
> 
> We already have NULL as the portable macro, so I would still prefer it
> to a Boost invention.
> 
> Again, that some compilers warn on NULL is a compiler bug and should be
> treated as such, IMO. Compiler vendors should keep their stylistic
> preferences to themselves, especially when they are impossible to follow
> (in C++03 case). The use of NULL as a null pointer is perfectly valid,
> in the sense of both formal C++ compliance and code readability.
> 

This happens when you write the code for C++03, but compile it for C++20.

I think it is pretty nice of the compiler to hint that things have 
changed in the last 20 years.