[Bug c++/42692] New: Invalid member lookup when member template class is involved

["igusarov at mail dot ru" <gcc-bugzilla at gcc dot gnu dot org>]

The bug is: if a class definition has a nested template class, then whenever a
code refers to a name in the nested class, gcc searches it not in the nested
template class, but it the outer class.

The bug results in gcc accepting a source text that should not be compiled, and
incorrectly compiling a valid source text. Complete compilable example is
included at the end of this report. I was able to reproduce this behaviour back
to gcc 4.2.1, 3.3.2 and 2.95.3.

Explanation. Please consider the following class definition:

struct root
{
  template <typename Y>
  struct chain
  {
  };
};

As you see, the structure root::chain<any_type> has no members. However, gcc
accepts and compiles type declarations like

typedef  root::chain<type_1>::chain<type_2>::chain<type_3>   my_type;

, where my_type becomes root::chain<type_3>, asif each "chain" template were
looked up in the "root" class.

You can use the following example to reproduce the bug. The example is
compilable, which is wrong.

//-----------------------------------------------
struct root
{
  template <typename Y>
  struct chain
  {
  };
};

struct o1;
struct o2;
struct o3;

typedef   root::chain<o1>                         p1;
typedef   root::chain<o2>::chain<o1>              p2;  /* <- should be error */
typedef   root::chain<o3>::chain<o2>::chain<o1>   p3;  /* <- should be error */

int main()
{
  p1     x1;
  p2     x2;
  p3     x3;

  x1 = x2 = x3; /* gcc thinks that they are of the same type! */

  return 0;
}


-- 
           Summary: Invalid member lookup when member template class is
                    involved
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: igusarov at mail dot ru
 GCC build triplet: amd64-unknown-freebsd7.1
  GCC host triplet: amd64-unknown-freebsd7.1
GCC target triplet: amd64-unknown-freebsd7.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42692