Code in derived class is allowed to access a base private non instance function when calls it unqualified

[bricknerb]

Description of the bug:

When a base class has non instanceprivate fn, its derived class can have a member function that calls it unqualified.
This access should be blocked.
When calling the base function in qualified way, this does result with the expected error.

What did you do, or what's a simple way to reproduce the bug?

Full example that should not compile, but does: https://godbolt.org/z/v3Pfo5sPG

Test:

carbon-lang/toolchain/check/testdata/class/inheritance_access.carbon

Line 151 in 4370acd

fn G() { F(); }

What did you expect to happen?

Compilation error.

What actually happened?

The call to the private function is made.

Any other information, logs, or outputs that you want to share?

No response