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
