[clang] [clang] Fix static_cast bypassing access control (PR #132285)

[Shafik Yaghmour via cfe-commits]

================
@@ -23,3 +22,66 @@ void test(A &a, B &b) {
   const A &&ar10 = static_cast<const A&&>(xvalue<A>());
   const A &&ar11 = static_cast<const A&&>(xvalue<B>());
 }
+
+struct C : private A { // expected-note 4 {{declared private here}}
----------------
shafik wrote:

Normally when we add tests to an existing file and it for a bug report we wrap them into  a namespace starting with `GH` for Github e.g `namespace GH121429` 

https://github.com/llvm/llvm-project/pull/132285