[Type checker] Make sure 'dynamic' gets set consistently.

'dynamic' is inherited and only applies to '@objc' entities.

The SourceKit test change is because we've changed our behavior
slightly: we won't infer @objc from an override unless the override is
correctly marked with 'override'. This is part of breaking up
dependencies, and should have little effect outside of tests.

Author: DougGregor

lib/Sema/TypeCheckDecl.cpp

@@ -1454,12 +1454,17 @@ static void inferDynamic(ASTContext &ctx, ValueDecl *D) {
     (D->getOverriddenDecl() &&
      D->getOverriddenDecl()->hasClangNode());
 
+  bool overridesDyanmic =
+    (D->getOverriddenDecl() &&
+     D->getOverriddenDecl()->isDynamic());
+
   bool isNSManaged = D->getAttrs().hasAttribute<NSManagedAttr>();
 
   bool isExtension = isa<ExtensionDecl>(D->getDeclContext());
 
   // We only infer 'dynamic' in these three cases.
-  if (!isExtension && !isNSManaged && !overridesImportedMethod)
+  if (!isExtension && !isNSManaged && !overridesImportedMethod &&
+      !overridesDyanmic)
     return;
 
   // The presence of 'final' blocks the inference of 'dynamic'.

lib/Sema/TypeCheckDeclOverride.cpp

@@ -1189,6 +1189,10 @@ namespace  {
       if (Override->isFinal())
         return;
 
+      // Must be @objc to be 'dynamic'.
+      if (!Override->isObjC())
+        return;
+
       makeDynamic(Override->getASTContext(), Override);
     }
 
@@ -1483,22 +1487,27 @@ static bool recordOverride(TypeChecker &TC, ValueDecl *override,
     diagnoseOverrideForAvailability(override, base);
   }
 
-  /// Check attributes associated with the base; some may need to merged with
-  /// or checked against attributes in the overriding declaration.
-  AttributeOverrideChecker attrChecker(base, override);
-  for (auto attr : base->getAttrs()) {
-    attrChecker.visit(attr);
-  }
-
   if (auto overridingFunc = dyn_cast<FuncDecl>(override)) {
     overridingFunc->setOverriddenDecl(cast<FuncDecl>(base));
   } else if (auto overridingCtor = dyn_cast<ConstructorDecl>(override)) {
     overridingCtor->setOverriddenDecl(cast<ConstructorDecl>(base));
   } else if (auto overridingASD = dyn_cast<AbstractStorageDecl>(override)) {
     auto *baseASD = cast<AbstractStorageDecl>(base);
     overridingASD->setOverriddenDecl(baseASD);
+  } else {
+    llvm_unreachable("Unexpected decl");
+  }
 
+  /// Check attributes associated with the base; some may need to merged with
+  /// or checked against attributes in the overriding declaration.
+  AttributeOverrideChecker attrChecker(base, override);
+  for (auto attr : base->getAttrs()) {
+    attrChecker.visit(attr);
+  }
+
+  if (auto overridingASD = dyn_cast<AbstractStorageDecl>(override)) {
     // Make sure we get consistent overrides for the accessors as well.
+    auto *baseASD = cast<AbstractStorageDecl>(base);
     assert(baseASD->getGetter());
 
     auto recordAccessorOverride = [&](AccessorKind kind) {
@@ -1536,8 +1545,6 @@ static bool recordOverride(TypeChecker &TC, ValueDecl *override,
     recordAccessorOverride(AccessorKind::Get);
     recordAccessorOverride(AccessorKind::Set);
     recordAccessorOverride(AccessorKind::MaterializeForSet);
-  } else {
-    llvm_unreachable("Unexpected decl");
   }
 
   return false;

test/SourceKit/CursorInfo/cursor_overrides.swift

@@ -5,11 +5,11 @@ protocol Prot {
 }
 
 class Cls : S1, Prot {
-  func meth() {}
+  override func meth() {}
 }
 
 class SubCls : Cls {
-  func meth() {}
+  override func meth() {}
 }
 
 func goo(x: SubCls) {
@@ -27,7 +27,7 @@ public protocol WithInheritedAssocType : WithAssocType {
 
 // REQUIRES: objc_interop
 // RUN: %sourcekitd-test -req=cursor -pos=16:7 %s -- -embed-bitcode -I %S/Inputs/cursor-overrides %mcp_opt %s | %FileCheck -check-prefix=CHECK1 %s
-// CHECK1: source.lang.swift.ref.function.method.instance (12:8-12:14)
+// CHECK1: source.lang.swift.ref.function.method.instance (12:17-12:23)
 // CHECK1: c:@M@cursor_overrides@objc(cs)SubCls(im)meth
 // CHECK1: (SubCls) -> () -> ()
 // CHECK1:      OVERRIDES BEGIN