In the following class template, the protected using declaration causes the
inherited member to become publicly accessible. The code compiles, even though
it shouldn't.
template <typename T> struct B
{
protected:
T v;
};
template <typename T> struct D : B<T>
{
protected:
using B<T>::v;
};
int main()
{
D<int> d;
d.v = 0;
return 0;
}
$ g++ test.cpp
The same code without templates gives the correct behaviour and doesn't
compile.
struct B
{
protected:
int v;
};
struct D : B
{
protected:
using B::v;
};
int main()
{
D d;
d.v = 0;
return 0;
}
$ g++ test.cpp
test.cpp: In function 'int main()':
test.cpp:4: error: 'int B::v' is protected
test.cpp:14: error: within this context
The preprocessed file from the template version is as follows:
# 1 "test.cpp"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "test.cpp"
template <typename T> struct B
{
protected:
T v;
};
template <typename T> struct D : B<T>
{
protected:
using B<T>::v;
};
int main()
{
D<int> d;
d.v = 0;
return 0;
}
--
Summary: Using declaration access semantics change with templates
Product: gcc
Version: 4.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: spam at david dot osborn dot name
GCC build triplet: i686-pc-mingw32
GCC host triplet: i686-pc-mingw32
GCC target triplet: i686-pc-mingw32
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29470
