Dependent names lookup in VC2005 B2

  • Thread starter Thread starter adebaene
  • Start date Start date
A

adebaene

Hello all,

I just checked that the following did compile with VC2005 b2, and I
think it shouldn't:

template <typename T> struct A
{
typedef int Foo;
};

template <typename T> class B : public A<T>
{
Foo i; //line 1
};


int main()
{
B<float> b;
}

I believe that Foo is a dependent-name in B context, and therefore line
1 should be "typename A<T>::Foo i;".

Comeau online and gcc seems to agree with my reasoning, but I am quite
unable to fully understand norm 14.6.2. Could anyone shed some light on
this? Is this code legal or not?

Arnaud
MVP - VC
 
Hello all,

I just checked that the following did compile with VC2005 b2, and I
think it shouldn't:

template <typename T> struct A
{
typedef int Foo;
};

template <typename T> class B : public A<T>
{
Foo i; //line 1
};


int main()
{
B<float> b;
}

I believe that Foo is a dependent-name in B context, and therefore line
1 should be "typename A<T>::Foo i;".

Comeau online and gcc seems to agree with my reasoning, but I am quite
unable to fully understand norm 14.6.2. Could anyone shed some light on
this? Is this code legal or not?
Click to expand...

No, the code above isn't legal. If you remove A<T> as a base class and
refer to Foo with A<T>::Foo, I expect you'll get an error. If instead you
add "int Foo;" as a global in front of B's defintion, I expect you won't
get an error. The problem is that VC still doesn't correctly implement the
"two-phase" lookup rule and is still quite lax about looking into template
bases.
 
Doug Harrison said:
Hello all,

I just checked that the following did compile with VC2005 b2, and I
think it shouldn't:

template <typename T> struct A
{
typedef int Foo;
};

template <typename T> class B : public A<T>
{
Foo i; //line 1
};


int main()
{
B<float> b;
}

I believe that Foo is a dependent-name in B context, and therefore line
1 should be "typename A<T>::Foo i;".

Comeau online and gcc seems to agree with my reasoning, but I am quite
unable to fully understand norm 14.6.2. Could anyone shed some light on
this? Is this code legal or not?
Click to expand...

No, the code above isn't legal. [...]
Click to expand...

I think it is indeed illegal. Comeau agrees.
<lazy_mode>I'm sure CW agrees, too. At least
it keeps finding such errors that VC let's
me get away with.</lazy_mode>

Schobi

--
(e-mail address removed) is never read
I'm Schobi at suespammers dot org

"Coming back to where you started is not the same as never leaving"
Terry Pratchett
 
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