[libSyntax] Make parsing of attribute arguments more structured

This also fixes several issues where attribute arguments could not be
parsed as a TokenList since some of its arguments already had structure
and were not tokens

Author: ahoppen

cmake/modules/SwiftHandleGybSources.cmake

@@ -116,6 +116,7 @@ function(handle_gyb_sources dependency_out_var_name sources_var_name arch)
       "${SWIFT_SOURCE_DIR}/utils/gyb_syntax_support/kinds.py"
       "${SWIFT_SOURCE_DIR}/utils/gyb_syntax_support/Node.py"
       "${SWIFT_SOURCE_DIR}/utils/gyb_syntax_support/AttributeNodes.py"
+      "${SWIFT_SOURCE_DIR}/utils/gyb_syntax_support/AvailabilityNodes.py"
       "${SWIFT_SOURCE_DIR}/utils/gyb_syntax_support/CommonNodes.py"
       "${SWIFT_SOURCE_DIR}/utils/gyb_syntax_support/DeclNodes.py"
       "${SWIFT_SOURCE_DIR}/utils/gyb_syntax_support/ExprNodes.py"

include/swift/Parse/Parser.h

@@ -768,16 +768,34 @@ class Parser {
   bool parseDeclAttributeList(DeclAttributes &Attributes,
                               bool &FoundCodeCompletionToken);
 
-  /// Parse the optional modifiers  before a declaration.
+  /// Parse the optional modifiers before a declaration.
   bool parseDeclModifierList(DeclAttributes &Attributes, SourceLoc &StaticLoc,
                              StaticSpellingKind &StaticSpelling);
 
+  /// Parse an availability attribute of the form
+  /// @available(*, introduced: 1.0, deprecated: 3.1).
+  /// \return \p nullptr if the platform name is invalid
+  ParserResult<AvailableAttr>
+  parseExtendedAvailabilitySpecList(SourceLoc AtLoc, SourceLoc AttrLoc,
+                                    StringRef AttrName);
+
+  /// Parse the Objective-C selector inside @objc
+  void parseObjCSelector(SmallVector<Identifier, 4> &Names,
+                         SmallVector<SourceLoc, 4> &NameLocs,
+                         bool &IsNullarySelector);
+
   /// Parse the @_specialize attribute.
   /// \p closingBrace is the expected closing brace, which can be either ) or ]
   /// \p Attr is where to store the parsed attribute
   bool parseSpecializeAttribute(swift::tok ClosingBrace, SourceLoc AtLoc,
                                 SourceLoc Loc, SpecializeAttr *&Attr);
 
+  /// Parse the arguments inside the @_specialize attribute
+  bool parseSpecializeAttributeArguments(
+      swift::tok ClosingBrace, bool &DiscardAttribute, Optional<bool> &Exported,
+      Optional<SpecializeAttr::SpecializationKind> &Kind,
+      TrailingWhereClause *&TrailingWhereClause);
+
   /// Parse the @_implements attribute.
   /// \p Attr is where to store the parsed attribute
   ParserResult<ImplementsAttr> parseImplementsAttribute(SourceLoc AtLoc,