RFC: change in std::type_info's equality operator

[Paolo Carlini]

Matt Austern wrote:

> I sent out a message yesterday suggesting a change in 
> std::type_info::operator==.  I didn't get a response, possibly because 
> my suggestion was buried in a message that largely talked about other 
> things.  (I began with a detailed discussion leading up to why the 
> change would be useful for certain purposes.)  So let's try again, and 
> this time I'll begin at the beginning.

Sorry about my personal lack of attention or lack of real understanding, 
I would say.

> Right now, depending on whether or not a certain macro is set when 
> libstdc++ is built, t1==t2 is equivalent to one of these two expressions:
>  (1) t1.__name == t2.__name, where __name is the address of the string 
> representing the type's name.
>  (2) t1.__name == t2.__name || strcmp(t1.__name, t2.__name) == 0.
>
> The library uses version (1) iff the compiler defines __GXX_WEAK__ to 
> be true.
>
> My proposal: change the library so it unconditionally uses version 2.  
> That is, always fall back to string comparison if the address comparison

Now it's much more clear (to me, at least).

I have double checked the standard ;) and everything seems ok with your 
proposal. Indeed, we are already using an identical strategy for 
locale::operator== (perhaps we could improve that implementation, but 
this is another story ;).

Let's wait for other opinions, though.

Paolo.