[cfe-dev] __is_empty type trait patch

[Anders Carlsson]

2 aug 2009 kl. 19.45 skrev Sean Hunt:

> Hello,
>
> I'm a new coder hoping to help out with the C++ implementation on  
> clang.
> After fiddling around with several things I discovered were all being
> worked on already, someone recommended I implement the __is_empty type
> trait, so that is what I did. I was told to send a message here now;
> I've attached a patch.

Nice, welcome! :)

>
>
>
> +  /// Empty - true when this class is empty for traits purposes,  
> i.e. has no
> +  /// data members other than 0-width bit-fields, has no virtual  
> function/base,
> +  /// and doesn't inherit from a non-empty class. Doesn't take  
> union-ness into
> +  /// account.
> +  bool Empty : 1;
> +

You don't have to store this - the ASTRecordLayout already stores the  
dataSize so you can just check to see if it's 0.

Anders