[Parse] Allow @_objcRuntimeName to be used in source.

rdar://problem/46546165

Author: mikeash

include/swift/AST/Attr.def

@@ -338,7 +338,7 @@ DECL_ATTR(_implements, Implements,
   NotSerialized, 67)
 DECL_ATTR(_objcRuntimeName, ObjCRuntimeName,
   OnClass |
-  UserInaccessible | RejectByParser |
+  UserInaccessible |
   NotSerialized, 68)
 SIMPLE_DECL_ATTR(_staticInitializeObjCMetadata, StaticInitializeObjCMetadata,
   OnClass | LongAttribute | RejectByParser |

include/swift/AST/DiagnosticsParse.def

@@ -1320,6 +1320,9 @@ ERROR(alignment_must_be_positive_integer,none,
 ERROR(swift_native_objc_runtime_base_must_be_identifier,none,
       "@_swift_native_objc_runtime_base class name must be an identifier", ())
 
+ERROR(objc_runtime_name_must_be_identifier,none,
+      "@_objcRuntimeName name must be an identifier", ())
+
 ERROR(attr_only_at_non_local_scope, none,
       "attribute '%0' can only be used in a non-local scope", (StringRef))
 

lib/Parse/ParseDecl.cpp

@@ -914,7 +914,6 @@ bool Parser::parseNewDeclAttribute(DeclAttributes &Attributes, SourceLoc AtLoc,
 
   case DAK_RawDocComment:
   case DAK_ObjCBridged:
-  case DAK_ObjCRuntimeName:
   case DAK_RestatedObjCConformance:
   case DAK_SynthesizedProtocol:
   case DAK_ClangImporterSynthesizedType:
@@ -1506,6 +1505,34 @@ bool Parser::parseNewDeclAttribute(DeclAttributes &Attributes, SourceLoc AtLoc,
     Attributes.add(attr);
     break;
   }
+  case DAK_ObjCRuntimeName: {
+    if (!consumeIf(tok::l_paren)) {
+      diagnose(Loc, diag::attr_expected_lparen, AttrName,
+               DeclAttribute::isDeclModifier(DK));
+      return false;
+    }
+
+    if (Tok.isNot(tok::identifier)) {
+      diagnose(Loc, diag::objc_runtime_name_must_be_identifier);
+      return false;
+    }
+
+    auto name = Tok.getText();
+
+    consumeToken(tok::identifier);
+
+    auto range = SourceRange(Loc, Tok.getRange().getStart());
+
+    if (!consumeIf(tok::r_paren)) {
+      diagnose(Loc, diag::attr_expected_rparen, AttrName,
+               DeclAttribute::isDeclModifier(DK));
+      return false;
+    }
+
+    Attributes.add(new (Context) ObjCRuntimeNameAttr(name, AtLoc, range,
+                                                     /*implicit*/ false));
+    break;
+  }
 
 
   case DAK_DynamicReplacement: {