c++/422: Unification algorithm for partial specialization too lenient

[gregod@rpi.edu]

>Number:         422
>Category:       c++
>Synopsis:       Unification algorithm for partial specialization too lenient
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 18 11:56:01 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator:     Douglas Gregor
>Release:        gcc version 2.95.2 19991024 (release)
>Organization:
>Environment:
i686-pc-linux
>Description:
g++ returns the error: ambiguous class template 
instantiation for `struct A<TypeWrapper<int>, true_type>'. 
In both partial specializations of A, T is bound to int, so
typename ProperyX<T>::is_valid (where X is 1 or 2) is known
and should be replaced with true_type and false_type for the
first and second partial specializations. This does not 
occur because TYPENAME_TYPEs are ignored in the unify()
function. 
>How-To-Repeat:
g++ unify_bug1.C
>Fix:
When all template parameters needed for a template argument
have been bound (T in the above case), the bound parameters
need to be substituted into parameters with nondeduced
contexts (e.g., TYPENAME_TYPE) and unification needs to be
rerun.
>Release-Note:
>Audit-Trail:
>Unformatted:
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