c++/10108: [3.4 regression] Error recovering problem: tree checking ICE: expected var_decl, have error_mark in tsubst_decl

[Giovanni Bajo]

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10108

Reduced snippet is:

---------------------------------------------------------------
template <class>
struct Foo
{};

template <class T>
struct Bar : public Foo<T>
{
    typedef Foo<T> base;
    typedef typename base::NON_EXISTENT INVALID_TYPE;

    template <class Q>
    Bar(Q q, INVALID_TYPE a)
        : base(a)
    {}
};

template struct Bar<void>;
---------------------------------------------------------------
pr10108.cpp: In instantiation of `Bar<void>':
pr10108.cpp:17:   instantiated from here
pr10108.cpp:9: error: no type named `NON_EXISTENT' in `struct Foo<void>'
pr10108.cpp:13: error: no type named `NON_EXISTENT' in `struct Foo<void>'
pr10108.cpp:13: internal compiler error: tree check: expected var_decl, have
   error_mark in tsubst_decl, at cp/pt.c:5957
Please submit a full bug report,

This is ICE on error recovery, confirmed with 3.4 CVS 20030503. The same
preprocessed source also generates totally different ICE-on-illegal for 3.2
branch and 3.3 branch. I isolated and reported the 3.3 branch failure in
c++/10594.

Giovanni Bajo