[AST] Introduce DeclAttrKind::Last_DeclAttr et al.

Instead of using dummy `_counting_KAK_*` global symbols, use
`LAST_DECL_ATTR` metaprogramming technique to determine the number of
enum values. This align with other "kind" enum e.g. `DeclKind`.

Author: rintaro

include/swift/AST/AttrKind.h

@@ -132,29 +132,25 @@ enum : unsigned { NumExternKindBits =
 
 enum class DeclAttrKind : unsigned {
 #define DECL_ATTR(_, CLASS, ...) CLASS,
+#define LAST_DECL_ATTR(CLASS) Last_DeclAttr = CLASS,
 #include "swift/AST/DeclAttr.def"
 };
 
 enum : unsigned {
-#define DECL_ATTR(_, C, ...) _counting_DAK_##C,
-#include "swift/AST/DeclAttr.def"
-  NumDeclAttrKinds,
-
-  NumDeclAttrKindBits = countBitsUsed(NumDeclAttrKinds - 1)
+  NumDeclAttrKinds = static_cast<unsigned>(DeclAttrKind::Last_DeclAttr) + 1,
+  NumDeclAttrKindBits = countBitsUsed(NumDeclAttrKinds - 1),
 };
 
 // Define enumerators for each type attribute, e.g. TypeAttrKind::Weak.
 enum class TypeAttrKind {
 #define TYPE_ATTR(_, CLASS) CLASS,
+#define LAST_TYPE_ATTR(CLASS) Last_TypeAttr = CLASS,
 #include "swift/AST/TypeAttr.def"
 };
 
 enum : unsigned {
-#define TYPE_ATTR(_, C) _counting_TAK_##C,
-#include "swift/AST/TypeAttr.def"
-  NumTypeAttrKinds,
-
-  NumTypeAttrKindBits = countBitsUsed(NumTypeAttrKinds - 1)
+  NumTypeAttrKinds = static_cast<unsigned>(TypeAttrKind::Last_TypeAttr) + 1,
+  NumTypeAttrKindBits = countBitsUsed(NumTypeAttrKinds - 1),
 };
 
 } // end namespace swift

include/swift/AST/DeclAttr.def

@@ -42,6 +42,9 @@
                    DECL_ATTR_ALIAS(SPELLING, CLASS)
 #endif
 
+#ifndef LAST_DECL_ATTR
+#define LAST_DECL_ATTR(CLASS)
+#endif
 
 // Declaration Attributes and Modifers
 DECL_ATTR(_silgen_name, SILGenName,
@@ -482,10 +485,12 @@ SIMPLE_DECL_ATTR(_noExistentials, NoExistentials,
 SIMPLE_DECL_ATTR(_noObjCBridging, NoObjCBridging,
   OnAbstractFunction | OnSubscript | UserInaccessible | ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove,
   155)
+LAST_DECL_ATTR(NoObjCBridging)
 
 #undef DECL_ATTR_ALIAS
 #undef CONTEXTUAL_DECL_ATTR_ALIAS
 #undef SIMPLE_DECL_ATTR
 #undef CONTEXTUAL_SIMPLE_DECL_ATTR
 #undef DECL_ATTR
 #undef CONTEXTUAL_DECL_ATTR
+#undef LAST_DECL_ATTR

include/swift/AST/TypeAttr.def

@@ -46,6 +46,10 @@
 #define SIMPLE_TYPE_ATTR(SPELLING, CLASS) TYPE_ATTR(SPELLING, CLASS)
 #endif
 
+#ifndef LAST_TYPE_ATTR
+#define LAST_TYPE_ATTR(CLASS)
+#endif
+
 // Type attributes
 SIMPLE_TYPE_ATTR(autoclosure, Autoclosure)
 TYPE_ATTR(convention, Convention)
@@ -105,7 +109,10 @@ SIMPLE_SIL_TYPE_ATTR(isolated, Isolated)
 SIMPLE_SIL_TYPE_ATTR(thin, Thin)
 SIMPLE_SIL_TYPE_ATTR(thick, Thick)
 
+LAST_TYPE_ATTR(Thick)
+
 #undef SIMPLE_SIL_TYPE_ATTR
 #undef SIMPLE_TYPE_ATTR
 #undef SIL_TYPE_ATTR
 #undef TYPE_ATTR
+#undef LAST_TYPE_ATTR