Re: anti-standard code can compile -- about template class

From:

"Igor Tandetnik" <itandetnik@mvps.org>

Newsgroups:

microsoft.public.vc.language

Date:

Fri, 7 Mar 2008 08:13:14 -0500

Message-ID:

<uvagCUFgIHA.2540@TK2MSFTNGP05.phx.gbl>

"George" <George@discussions.microsoft.com> wrote in message
news:E878B4CB-BACA-4D45-996C-0CAFACFAE58A@microsoft.com

According to standard, the code should not compile.

[Code]
     template <typename T> struct Base {
        int i;
      };

      template <typename T> struct Derived : public Base<T> {
        int get_i() { return i; }
      };

[/Code]

MSVC doesn't implement two-phase name lookup. All names, dependent or
otherwise, are looked up at the point of instantiation, none at the
point of definition. This is a well-known and long-standing limitation.

In fact, MSVC doesn't even check the syntax inside a template until
instantiation time. Try this:

template <typename T>
void f() {
blah blah blah
}

As long as you never actually call f, this nonsense will compile on
MSVC.
--
With best wishes,
Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925