re PR c++/58022 (Compiler rejects abstract class in template class with friend operator<<)

	PR c++/58022
	* g++.dg/template/abstract1.C: New.

From-SVN: r201337

gcc/testsuite/g++.dg/template/abstract1.C

+// PR c++/58022
+
+template <class T> struct A { };
+template <class T> A<T> & operator<< (A<T>&, T);
+template <class T> class foo;
+template <class T> A<char> & operator<<(A<char>& o, const foo<T>& l);
+template <class T> class foo  {
+    friend A<char>& operator<< <T> (A<char>& o, const foo<T>& l);
+};
+class bar;
+foo<bar> fb;
+class bar { virtual void baz()=0; };