Implement the Objective-C __kindof type qualifier.

The __kindof type qualifier can be applied to Objective-C object
(pointer) types to indicate id-like behavior, which includes implicit
"downcasting" of __kindof types to subclasses and id-like message-send
behavior. __kindof types provide better type bounds for substitutions
into unspecified generic types, which preserves more type information.

llvm-svn: 241548

1 files changed, 19 insertions, 0 deletions

diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 9c12abab39d..bc253f7f861 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -2601,6 +2601,7 @@ Parser::DiagnoseMissingSemiAfterTagDefinition(DeclSpec &DS, AccessSpecifier AS,
 /// [C11]   alignment-specifier declaration-specifiers[opt]
 /// [GNU]   attributes declaration-specifiers[opt]
 /// [Clang] '__module_private__' declaration-specifiers[opt]
+/// [ObjC1] '__kindof' declaration-specifiers[opt]
 ///
 ///       storage-class-specifier: [C99 6.7.1]
 ///         'typedef'
@@ -3083,6 +3084,13 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
       ParseNullabilityTypeSpecifiers(DS.getAttributes());
       continue;
 
+    // Objective-C 'kindof' types.
+    case tok::kw___kindof:
+      DS.getAttributes().addNew(Tok.getIdentifierInfo(), Loc, nullptr, Loc,
+                                nullptr, 0, AttributeList::AS_Keyword);
+      (void)ConsumeToken();
+      continue;
+
     // storage-class-specifier
     case tok::kw_typedef:
       isInvalid = DS.SetStorageClassSpec(Actions, DeclSpec::SCS_typedef, Loc,
@@ -4345,6 +4353,8 @@ bool Parser::isTypeSpecifierQualifier() {
   case tok::kw__Nullable:
   case tok::kw__Null_unspecified:
 
+  case tok::kw___kindof:
+
   case tok::kw___private:
   case tok::kw___local:
   case tok::kw___global:
@@ -4525,6 +4535,8 @@ bool Parser::isDeclarationSpecifier(bool DisambiguatingWithExpression) {
   case tok::kw__Nullable:
   case tok::kw__Null_unspecified:
 
+  case tok::kw___kindof:
+
   case tok::kw___private:
   case tok::kw___local:
   case tok::kw___global:
@@ -4762,6 +4774,13 @@ void Parser::ParseTypeQualifierListOpt(DeclSpec &DS, unsigned AttrReqs,
       ParseNullabilityTypeSpecifiers(DS.getAttributes());
       continue;
 
+    // Objective-C 'kindof' types.
+    case tok::kw___kindof:
+      DS.getAttributes().addNew(Tok.getIdentifierInfo(), Loc, nullptr, Loc,
+                                nullptr, 0, AttributeList::AS_Keyword);
+      (void)ConsumeToken();
+      continue;
+
     case tok::kw___attribute:
       if (AttrReqs & AR_GNUAttributesParsedAndRejected)
         // When GNU attributes are expressly forbidden, diagnose their usage.