Add a release note and test cases for const and volatile pointers

Author: ahatanaka

clang/docs/ReleaseNotes.rst

@@ -325,6 +325,9 @@ Non-comprehensive list of changes in this release
   ``__reference_constructs_from_temporary`` should be used instead. (#GH44056)
 - Added `__builtin_get_vtable_pointer` to directly load the primary vtable pointer from a
   polymorphic object.
+- Clang no longer rejects reinterpret_cast conversions between indirect
+  ARC-managed pointers and other pointer types. The prior behavior was overly
+  strict and inconsistent with the ARC specification.
 
 New Compiler Flags
 ------------------

clang/test/SemaObjCXX/arc-type-conversion.mm

@@ -76,13 +76,17 @@ void test_reinterpret_cast(__strong id *sip, __weak id *wip,
   (void)reinterpret_cast<__weak id *>(csip); // expected-error{{reinterpret_cast from '__strong id const *' to '__weak id *' casts away qualifiers}}
   (void)reinterpret_cast<__strong id *>(cwip); // expected-error{{reinterpret_cast from '__weak id const *' to '__strong id *' casts away qualifiers}}
 
-  auto *p0 = reinterpret_cast<unsigned long *>(sip);
-  (void)reinterpret_cast<__strong id *>(p0);
-  auto *p1 = reinterpret_cast<__weak NSString *>(sip);
-  (void)reinterpret_cast<__strong id *>(p1);
+  auto *ul = reinterpret_cast<unsigned long *>(sip);
+  (void)reinterpret_cast<__strong id *>(ul);
+  auto *wp = reinterpret_cast<__weak NSString *>(sip);
+  (void)reinterpret_cast<__strong id *>(wp);
   (void)reinterpret_cast<unsigned long *>(csip); // expected-error {{reinterpret_cast from '__strong id const *' to 'unsigned long *' casts away qualifiers}}
-  const unsigned long *p2 = nullptr;
-  (void)reinterpret_cast<__strong id *>(p2); // expected-error {{reinterpret_cast from 'const unsigned long *' to '__strong id *' casts away qualifiers}}
+  const unsigned long *cul = nullptr;
+  (void)reinterpret_cast<__strong id *>(cul); // expected-error {{reinterpret_cast from 'const unsigned long *' to '__strong id *' casts away qualifiers}}
+  volatile __strong id *vsip = nullptr;
+  (void)reinterpret_cast<unsigned long *>(vsip); // expected-error {{reinterpret_cast from '__strong id volatile *' to 'unsigned long *' casts away qualifiers}}
+  volatile unsigned long *vul = nullptr;
+  (void)reinterpret_cast<__strong id *>(vul); // expected-error {{reinterpret_cast from 'volatile unsigned long *' to '__strong id *' casts away qualifiers}}
   auto uip = reinterpret_cast<uintptr_t>(sip);
   (void)reinterpret_cast<__strong id *>(uip); // expected-error {{to '__strong id *' is disallowed with ARC}}
 }