https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118218
Bug ID: 118218
Summary: GCC allows the instantiation of private nested classes
in a base class from a derived class in a multi-level
inheritance chain
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: wangbopku15 at gmail dot com
Target Milestone: ---
Consider the following code:
~~~~~~~~~~~~~~~~~~~~~~~~~~~
struct B {
struct X {};
};
class C: private B{};
struct D : private C{
struct X x;
};
int main(){
D d;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~
It seems that struct 'X' should be invisible within struct 'D', as class 'C'
private inherits 'B', which makes 'C::X' private. GCC accepts the code but
MSVC, EDG and clang all reject it, with error messages like:
~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:7:10: error: 'X' is a private member of 'B'
7 | struct X x;
| ^
<source>:5:11: note: constrained by implicitly private inheritance here
5 | class C : B{};
| ^
<source>:2:10: note: member is declared here
2 | struct X {};
| ^
1 error generated.
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Please see https://godbolt.org/z/Eq5xnzd9o
