[C++ Patch] PR 3761 (ICE in check_template_shadow)

[Scott Brumbaugh <scottb dot lists at verizon dot net>]

Hi,

Here is an attempt at fixing this bug.  My analysis was done on the
test code listed below. The error occurs because a TREE_LIST is passed
as an argument to check_template_shadow.  I traced this back to an
ambiguous lookup of the implicit operator= which is defined in both base
classes A and B.

This lookup is done in setup_class_bindings when it calls
lookup_member with the protect parameter = 2.  In this case
lookup_member will return a TREE_LIST node with TREE_TYPE set to
error_mark_node and TREE_VALUE set to a chain of ambiguous candidates.
This returned TREE_LIST is then passed to push_class_level_binding
which is the function that calls check_template_shadow.

To fix this I changed check_template_shadow by adding an explicit
check for a TREE_LIST argument with a TREE_TYPE of error_mark_node.
In this case the decl chain of ambiguous names is extracted and the
function continues on.

Here is a patch that implements this fix followed by a test case.
I have done a make bootstrap and make check-g++ on i686-pc-linux-gnu.


Thanks,

Scott Brumbaugh


2003-08-22  Scott Brumbaugh  <scottb.lists@verizon.net>


	PR C++/3761

	* pt.c (check_template_shadow): Look out for a TREE_LIST of
	ambiguous names.  Handle this list just as an OVERLOAD list.

	

Index: pt.c
===================================================================
RCS file: /cvsroot/gcc/gcc/gcc/cp/pt.c,v
retrieving revision 1.763
diff -c -3 -p -r1.763 pt.c
*** pt.c	21 Aug 2003 05:50:52 -0000	1.763
--- pt.c	22 Aug 2003 00:08:44 -0000
*************** check_template_shadow (tree decl)
*** 1932,1937 ****
--- 1932,1944 ----
    /* Figure out what we're shadowing.  */
    if (TREE_CODE (decl) == OVERLOAD)
      decl = OVL_CURRENT (decl);
+   /* lookup_member will return a TREE_LIST if a name is ambiguous, the
+      TREE_TYPE will be error_mark_node, TREE_VALUE will hold all the
+      ambiguous candidates. */
+   else if (TREE_CODE (decl) == TREE_LIST 
+ 	   && TREE_TYPE (decl) == error_mark_node)
+     decl = TREE_VALUE (decl);
+ 
    olddecl = IDENTIFIER_VALUE (DECL_NAME (decl));
  
    /* If there's no previous binding for this name, we're not shadowing


// { dg-do compile }
//
// PR 3761

struct A {};
 
struct B {};
 
template <class T>
struct Foo : A, B
{
    void func(void);

    struct Nested
    {
        friend void Foo::func(void);
    };
};