Patch for g++ template bug

Patch for g++ template bug

[Mark Mitchell]

Enclosed is a bug description and patch for a g++ template bug.
Please let me know if there is anything I can do to help get this
patch installed.

-- 
Mark Mitchell		mmitchell@usa.net
Stanford University	http://www.stanford.edu

Description
-----------

g++ emits an incorrect error message on a valid use of templates, and
therefore produces no object code.  Enclosed below is the error message and 
the source file:

    supernova% g++ -v
    Reading specs from /home/mitchell/egcs/lib/gcc-lib/i686-pc-linux-gnulibc1/egcs-2.90.01/specs
    gcc version egcs-2.90.01 970821 (gcc2-970802 experimental)
    supernova% g++ -c test.cpp
    test.cpp:18: new declaration `struct A<U *> B<U>::foo()'
    test.cpp:13: ambiguates old declaration `struct A<U *> B<U>::foo()'

    test.cpp
    --------
    template <class T>
    struct A
    {
      A(T t);
    };


    template <class U>
    struct B
    {
      typedef A<U*>  a;

      A<const U*> foo();
    };

    template <class U>
    A<const U*> B<U>::foo()
    {
    }

    void f()
    {
      B<char> b;

      b.foo();
    }

Note that the error message mentions A<U *> when in fact A<const U*>
is the appropriate type.  This is only a bug in the type_as_string()
function; the type is actually "const U" judging by the
TREE_READONLY() bit.  In addition, since the declarations are
identical, there should be no ambiguity.

Fix
---

Below is the marvelously simple fix, does not merely correct the error
message, but in fact makes it go away completely!

Index: cp/ChangeLog
===================================================================
RCS file: /home/mitchell/Repository/egcs/cp/ChangeLog,v
retrieving revision 1.1.1.2
diff -c -r1.1.1.2 ChangeLog
*** ChangeLog   1997/08/22 06:35:53     1.1.1.2
--- ChangeLog   1997/08/24 01:04:44
***************
*** 1,3 ****
--- 1,8 ----
+ Sat Aug 23 18:02:59 1997  Mark Mitchell  <mmitchell@usa.net>
+ 
+       * error.c (type_as_string): Put const/volatile on template type
+       parameters where appropriate.
+ 
  Thu Aug 21 18:48:44 1997  Jason Merrill  <jason@yorick.cygnus.com>
  
        * lex.c (real_yylex): Refer to __complex instead of complex.
Index: cp/error.c
===================================================================
RCS file: /home/mitchell/Repository/egcs/cp/error.c,v
retrieving revision 1.1.1.2
diff -c -r1.1.1.2 error.c
*** error.c     1997/08/22 06:35:58     1.1.1.2
--- error.c     1997/08/24 01:05:02
***************
*** 230,235 ****
--- 230,236 ----
        break;
  
      case TEMPLATE_TYPE_PARM:
+       dump_readonly_or_volatile (t, after);
        if (TYPE_IDENTIFIER (t))
        OB_PUTID (TYPE_IDENTIFIER (t));
        else