[Boost-users] gcc-3.4.1 and add_const

From: Alexander Neubeck (aneubeck_at_[hidden])
Date: 2004-10-26 06:43:56

Hi.

I recognized a strange (wrong?) behaviour of gcc-3.4.1 (and gcc-3.3.3).

When adding const to a type T and this type T is a reference, the result 
is just T again (with reference, but witout const)!
Then I tested, if boost handles this case correctly, and it didn't.
The type of add_const< int & >::result is int & and not as expected 
const int &.

Next I was looking into the boost-Implementation of add_const and found 
something like (hidden in a makro):

template< class T >
struct add_const {
   typedef const T result;
// same result with:
// typedef T const result;
};

The only way I could get the correct behaviour was to add 
specializations for ALL combinations:

template< class T >
struct add_const< T & > {
   typedef const T & result;
};

template< class T >
struct add_const< const T & > {
   typedef const T & result;
};

template< class T >
struct add_const< T * > {
   typedef const T * result;
};

...

My questions to you:
Can anybody verify this behaviour?
Is this behaviour intended?
If yes, WHY?

thx a lot
   Alexander

P.S:
It was quite difficult to check, which result-type the add_const really 
created. First I used typeid( ... ).name(). But then I recognized that 
int, int &, const int & produce ALL THE SAME name?!?
Therefore I used an abstract function with the unknown type. In a 
derived class I overloaded all possible solutions and printed the 
CORRECT type...
Any suggestions here?