c++/11: bogus instantiation during template deduction

[nathan at codesourcery dot com]

>Number:         11
>Category:       c++
>Synopsis:       bogus instantiation during template deduction
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Mar 01 09:16:01 PST 2000
>Closed-Date:
>Last-Modified:
>Originator:     Ewgenij Gawrilow <gawrilow@math.TU-Berlin.DE>
>Release:        CVS 20000229
>Organization:
>Environment:
All
>Description:
The following piece of code can't be compiled by gcc 2.95.2.

#line 1 "prob.cc"
template <class C>
struct A {
   typedef typename C::obj obj;
   typedef typename C::cobj cobj;

   static obj g(C& c) { return c.g(); }
   static cobj g(const C& c) { return c.g(); }
};

#if defined(WORK_AROUND)
template <class C>
struct A<const C> {
   typedef typename C::cobj obj;
};
#endif

template <class C> inline
A<C>::obj g(C& c)
{
   return A<C>::g(c);
}

template <class C> inline
A<C>::cobj g(const C& c)
{
   return A<C>::g(c);
}

class cont {
public:
   class obj { };
   class cobj { };
   obj g();
   cobj g() const;
};

void f(const cont& c)
{
   g(c);
}


prob.cc: In instantiation of `A<const cont>':
prob.cc:19:   instantiated from here
prob.cc:7: `A<const cont>::g(const cont &)' has already been declared in `A<const cont>'


It seems as if the template parameter deduction is being made twice, once when
analyzing the return value of g(c) within f(), and then during the
instantiation of the body of ::g. It wasn't that bad, hadn't the first attempt
lead to wrong results.
>How-To-Repeat:
during deduction of the call to Baz, A<const int> is
instantiated. This fails, but should just be rejected, not
cause a diagnostic [14.8.2]/2
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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