[4.0] Add a size heuristic to the Space Engine

include/swift/AST/Attr.def

@@ -286,6 +286,11 @@ SIMPLE_DECL_ATTR(NSKeyedArchiverEncodeNonGenericSubclassesOnly,
                  OnClass | NotSerialized | LongAttribute,
                  /*Not serialized */ 70)
 
+// HACK: Attribute needed to preserve source compatibility by downgrading errors
+// due to an SDK change in Dispatch
+SIMPLE_DECL_ATTR(_downgrade_exhaustivity_check, DowngradeExhaustivityCheck,
+                 OnEnumElement | LongAttribute | UserInaccessible, 71)
+
 #undef TYPE_ATTR
 #undef DECL_ATTR_ALIAS
 #undef SIMPLE_DECL_ATTR

include/swift/AST/DiagnosticsSema.def

@@ -3701,6 +3701,10 @@ NOTE(missing_particular_case,none,
 WARNING(redundant_particular_case,none,
         "case is already handled by previous patterns; consider removing it",())
 
+// HACK: Downgrades the above to warnings if any of the cases is marked
+// @_downgrade_exhaustivity_check.
+WARNING(non_exhaustive_switch_warn_swift3,none, "switch must be exhaustive", ())
+
 #ifndef DIAG_NO_UNDEF
 # if defined(DIAG)
 #  undef DIAG

lib/AST/ASTDumper.cpp

@@ -840,6 +840,8 @@ namespace {
 
     void visitEnumElementDecl(EnumElementDecl *EED) {
       printCommon(EED, "enum_element_decl");
+      if (EED->getAttrs().hasAttribute<DowngradeExhaustivityCheckAttr>())
+        OS << "@_downgrade_exhaustivity_check";
       PrintWithColorRAII(OS, ParenthesisColor) << ')';
     }
 

lib/AST/Attr.cpp

@@ -506,6 +506,10 @@ bool DeclAttribute::printImpl(ASTPrinter &Printer, const PrintOptions &Options,
     Printer.printAttrName("@_staticInitializeObjCMetadata");
     break;
 
+  case DAK_DowngradeExhaustivityCheck:
+    Printer.printAttrName("@_downgrade_exhaustivity_check");
+    break;
+
   case DAK_Count:
     llvm_unreachable("exceed declaration attribute kinds");
 

lib/Sema/TypeCheckAttr.cpp

@@ -107,6 +107,7 @@ class AttributeEarlyChecker : public AttributeVisitor<AttributeEarlyChecker> {
   IGNORED_ATTR(NSKeyedArchiverClassName)
   IGNORED_ATTR(StaticInitializeObjCMetadata)
   IGNORED_ATTR(NSKeyedArchiverEncodeNonGenericSubclassesOnly)
+  IGNORED_ATTR(DowngradeExhaustivityCheck)
 #undef IGNORED_ATTR
 
   // @noreturn has been replaced with a 'Never' return type.
@@ -784,6 +785,7 @@ class AttributeChecker : public AttributeVisitor<AttributeChecker> {
     IGNORED_ATTR(ObjCMembers)
     IGNORED_ATTR(StaticInitializeObjCMetadata)
     IGNORED_ATTR(NSKeyedArchiverEncodeNonGenericSubclassesOnly)
+    IGNORED_ATTR(DowngradeExhaustivityCheck)
 #undef IGNORED_ATTR
 
   void visitAvailableAttr(AvailableAttr *attr);

lib/Sema/TypeCheckDecl.cpp

@@ -6103,6 +6103,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
     UNINTERESTING_ATTR(NSKeyedArchiverClassName)
     UNINTERESTING_ATTR(StaticInitializeObjCMetadata)
     UNINTERESTING_ATTR(NSKeyedArchiverEncodeNonGenericSubclassesOnly)
+    UNINTERESTING_ATTR(DowngradeExhaustivityCheck)
 #undef UNINTERESTING_ATTR
 
     void visitAvailableAttr(AvailableAttr *attr) {

lib/Sema/TypeCheckProtocol.cpp

@@ -5915,7 +5915,7 @@ static bool hasGenericAncestry(ClassDecl *classDecl) {
 /// Infer the attribute tostatic-initialize the Objective-C metadata for the
 /// given class, if needed.
 static void inferStaticInitializeObjCMetadata(ClassDecl *classDecl,
-                                               bool requiresNSCodingAttr) {
+                                              bool requiresNSCodingAttr) {
   // If we already have the attribute, there's nothing to do.
   if (classDecl->getAttrs().hasAttribute<StaticInitializeObjCMetadataAttr>())
     return;