[NFC] Improve wording and usage of subscript/deinit flag

Author: beccadax

include/swift/Parse/Parser.h

@@ -1422,7 +1422,7 @@ class Parser {
 
     /// If passed, 'deinit' and 'subscript' should be parsed as special names,
     /// not ordinary identifiers.
-    UseSpecialNamesForDeinitAndSubscript = AllowKeywords | 1 << 2,
+    AllowKeywordsUsingSpecialNames = AllowKeywords | 1 << 2,
 
     /// If passed, compound names with argument lists are allowed, unless they
     /// have empty argument lists.

lib/Parse/ParseDecl.cpp

@@ -1129,8 +1129,8 @@ ParserResult<DerivativeAttr> Parser::parseDerivativeAttribute(SourceLoc atLoc,
       original.Name = parseDeclNameRef(original.Loc,
           diag::attr_derivative_expected_original_name,
           DeclNameFlag::AllowZeroArgCompoundNames |
-          DeclNameFlag::AllowKeywords | DeclNameFlag::AllowOperators |
-          DeclNameFlag::UseSpecialNamesForDeinitAndSubscript);
+          DeclNameFlag::AllowKeywordsUsingSpecialNames |
+          DeclNameFlag::AllowOperators);
     }
     if (consumeIfTrailingComma())
       return makeParserError();
@@ -2061,8 +2061,8 @@ bool Parser::parseNewDeclAttribute(DeclAttributes &Attributes, SourceLoc AtLoc,
         replacedFunction = parseDeclNameRef(loc,
             diag::attr_dynamic_replacement_expected_function,
             DeclNameFlag::AllowZeroArgCompoundNames |
-            DeclNameFlag::AllowKeywords | DeclNameFlag::AllowOperators |
-            DeclNameFlag::UseSpecialNamesForDeinitAndSubscript);
+            DeclNameFlag::AllowKeywordsUsingSpecialNames |
+            DeclNameFlag::AllowOperators);
       }
     }
 

lib/Parse/ParseExpr.cpp

@@ -2176,7 +2176,7 @@ DeclNameRef Parser::parseDeclNameRef(DeclNameLoc &loc,
     baseNameLoc = consumeToken();
   } else if (flags.contains(DeclNameFlag::AllowKeywords) && Tok.isKeyword()) {
     bool specialDeinitAndSubscript =
-        flags.contains(DeclNameFlag::UseSpecialNamesForDeinitAndSubscript);
+        flags.contains(DeclNameFlag::AllowKeywordsUsingSpecialNames);
 
     // Syntax highlighting should treat this token as an identifier and
     // not as a keyword.