[clang] Add test for CWG360

[Endill]

Summary

P1787: "CWG360 is resolved by applying access control to using-declarations."
class.access.general#4: "When a using-declarator is named, access control is applied to it, not to the declarations that replace it."

[Endill]

run make_cxx_dr_status

[aaron.ballman]

LGTM!

[erichkeane]

clang/test/CXX/drs/dr3xx.cpp

908

This bookmark isn't necessary, so no reason to have it. But thank you for using these!

[Endill]

clang/test/CXX/drs/dr3xx.cpp

908

Nice catch, thank you!
Seems like I should've waited a bit more before committing.

[aaron.ballman]

clang/test/CXX/drs/dr3xx.cpp

908

Good catch Erich!

Feel free to fix the comment up with an NFC commit (you don't need anyone to review it because there's no functional change).

[erichkeane]

clang/test/CXX/drs/dr3xx.cpp

908

Don't worry about it, this is a trivial issue I just saw while scrolling/admiring the bookmarks :D a follow-up review-after-commit patch would be fine here.

clang/test/CXX/drs/dr3xx.cpp

union {
 
       union { // expected-error {{extension}}
         int u;
       };
     };
   };
 }
 
+namespace dr360 { // dr360: yes
+struct A {
+  int foo();
+  int bar();
+
+protected:
+  int baz();
+};
+
+struct B : A {
+private:
+  using A::foo; // #dr360-foo-using-decl
+protected:
+  using A::bar; // #dr360-bar-using-decl
+public:
+  using A::baz; // #dr360-baz-using-decl
+};
+
+int main() {
+  int foo = B().foo(); // expected-error {{is a private member}}
+  // expected-note@#dr360-foo-using-decl {{declared private here}}
+  int bar = B().bar(); // expected-error {{is a protected member}}
+  // expected-note@#dr360-bar-using-decl {{declared protected here}}
+  int baz = B().baz();
+}
+} // namespace dr360
+
 // dr362: na
 // dr363: na
 
 namespace dr364 { // dr364: yes
   struct S {
     static void f(int);
     void f(char);
   };

clang/www/cxx_dr_status.html

<tr id="359">
     <td>NAD</td>
     <td>Type definition in anonymous union</td>
     <td class="full" align="center">Yes</td>
   </tr>
   <tr id="360">
     <td><a href="https://wg21.link/cwg360">360</a></td>
     <td>CD6</td>
     <td>Using-declaration that reduces access</td>
-    <td class="none" align="center">Unknown</td>
+    <td class="full" align="center">Yes</td>
   </tr>
   <tr class="open" id="361">
     <td><a href="https://wg21.link/cwg361">361</a></td>
     <td>open</td>
     <td>Forward reference to default argument</td>
     <td align="center">Not resolved</td>
   </tr>
   <tr id="362">