c++/6079: Access error message discrepancy between template & plain class

[jdonner@schedsys.com]

>Number:         6079
>Category:       c++
>Synopsis:       Access error message discrepancy between template & plain class
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    unassigned
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Wed Mar 27 20:46:01 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     JDonner
>Release:        gcc 3.0.4
>Organization:
>Environment:
Reading specs from /usr/local/gcc304/lib/gcc-lib/i686-pc-linux-gnu/3.0.4/specs
Configured with: /home/jdonner/mk304/gcc-3.0.4/configure --prefix=/usr/local/gcc304 --enable-threads
Thread model: posix
gcc version 3.0.4
>Description:
In some circumstances g++ doesn't warn about a hidden type as directly as in others.

// badtypedef.cpp
#if defined(CASE1)
#   define TMPL_ERR_MSG
#elif defined(CASE2)
#   define TMPL_ERR_MSG
#   define TMPL_ERR_HELPER
#endif
struct Highup{Highup() {}};

class Base : public Highup {
  typedef Highup Inherited;
  struct Secret{};
public:
  Base() : Inherited() {}
};

#ifdef TMPL_ERR_MSG
template <class SomeT>
#endif
struct Derived : public Base {
  Derived(int x) : Inherited() {
#ifdef TMPL_ERR_HELPER
  Secret s;
#endif
}
};

int main() { Derived<int> d(3); }
///////////////////////////////////////

-- Normal case;

jdonner@deathstar ~> g++ badtypedef.cpp
badtypedef.cpp: In constructor `Derived::Derived(int)':
badtypedef.cpp:11: `typedef struct Highup Base::Inherited' is private
badtypedef.cpp:21: within this context


-- Making Derived a template, g++ no longer says explicitly that 
-- 'Inherited' is private;

jdonner@deathstar ~> g++ -DCASE1 badtypedef.cpp
badtypedef.cpp: In constructor `Derived<SomeT>::Derived(int) [with SomeT = int]':
badtypedef.cpp:28:   instantiated from here
badtypedef.cpp:21: `Highup' is not an immediate base class of `Derived<int>'


-- But referring to another hidden type restores the message about 'Inherited'.

jdonner@deathstar ~> g++ -DCASE2 badtypedef.cpp
badtypedef.cpp: In constructor `Derived<SomeT>::Derived(int)':
badtypedef.cpp:12: `struct Base::Secret' is private
badtypedef.cpp:23: within this context
badtypedef.cpp:11: `typedef struct Highup Base::Inherited' is private
badtypedef.cpp:23: within this context
badtypedef.cpp: In constructor `Derived<SomeT>::Derived(int) [with SomeT = int]':
badtypedef.cpp:28:   instantiated from here
badtypedef.cpp:21: `Highup' is not an immediate base class of `Derived<int>'


g++ 2.95 does the same thing except CASE2 is no different from CASE1.
>How-To-Repeat:

>Fix:

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