add killswitch for raise_notice on Reflection::getConstants

Summary: Add a killswitch for raising notice whenever  `ReflectionClass::getConstants` is used on enums or enum classes that use/extend other enums.

Reviewed By: viratyosin

Differential Revision: D65240052

fbshipit-source-id: 5109742c83f19c2cdd8d3237e90cb41d42fca45a

hphp/doc/configs.specification

@@ -275,6 +275,11 @@ The format can be found in hphp/tools/configs/generate-configs.rs
 
   Synchronize class loading between threads
 
+- bool Eval.ReflectionMissConstantFromIncludedEnumsNotice = false, fzn
+
+  Whether ReflectionClass::getConstants raises notice if it misses constants from
+  enums/enum classes included via enum inclusion
+
 # Hack.Lang
 
 - bool Hack.Lang.DisableLvalAsAnExpression = false, UNKNOWN, repooptionsflag(Parser)|hackc(parser)

hphp/runtime/ext/reflection/ext_reflection.cpp

@@ -1640,7 +1640,8 @@ void addClassConstantNames(const Class* cls,
       }
     }
   }
-  if (has_constants_from_included_enums) {
+  if (has_constants_from_included_enums && 
+      Cfg::Eval::ReflectionMissConstantFromIncludedEnumsNotice) {
     raise_notice(Strings::REFLECTION_MISS_CONSTANTS_FROM_INCLUDED_ENUMS, 
                  cls->name()->data());
   }

hphp/test/slow/enum_supertyping/reflection.php.opts

@@ -0,0 +1 @@
+-vEval.ReflectionMissConstantFromIncludedEnumsNotice=true