Lower error to warning, fix tests for objc interopg

Author: mininny

include/swift/AST/DiagnosticsSema.def

@@ -1504,8 +1504,8 @@ ERROR(access_control_extension_open,none,
 ERROR(access_control_open_bad_decl,none,
       "only classes and overridable class members can be declared 'open';"
       " use 'public'", ())
-ERROR(access_control_non_objc_open_func,none,
-      "non-@objc %select{properties|methods}0 in extensions cannot be overriden; use 'public' instead",
+WARNING(access_control_non_objc_open_member,none,
+      "non-'@objc' %select{properties|methods}0 in extensions cannot be overridden; use 'public' instead",
       (bool))
 
 ERROR(invalid_decl_attribute,none,

lib/Sema/TypeCheckAttr.cpp

@@ -794,14 +794,17 @@ void AttributeChecker::visitAccessControlAttr(AccessControlAttr *attr) {
                  extAttr->getAccess())
           .fixItRemove(attr->getRange());
       }
-    }
-
-    if (auto VD = dyn_cast<ValueDecl>(D)) {
-      if (!VD->isObjC() && attr->getAccess() == AccessLevel::Open) {
-        diagnose(attr->getLocation(), diag::access_control_non_objc_open_func,
-                 isa<FuncDecl>(VD))
-            .fixItReplace(attr->getRange(), "public");
-        attr->setInvalid();
+    } else {
+      if (auto VD = dyn_cast<ValueDecl>(D)) {
+        // Emit warning when trying to declare non-@objc `open` member inside an
+        // extension.
+        if (!VD->isObjC() && attr->getAccess() == AccessLevel::Open) {
+          diagnose(attr->getLocation(),
+                   diag::access_control_non_objc_open_member,
+                   isa<AbstractFunctionDecl>(VD))
+              .fixItReplace(attr->getRange(), "public");
+          attr->setInvalid();
+        }
       }
     }
   }

test/attr/open.swift

@@ -134,21 +134,3 @@ open class OpenSubClass : OpenSuperClass {
   open override subscript(index: MarkerForNonOpenSubscripts) -> Int { return 0 }
 
 }
-
-open class InvalidOpenExtension {
-  open func openMethod() { } // No error
-}
-extension InvalidOpenExtension {
-  open func nonObjcOpenMethod() { } // expected-error {{non-@objc methods in extensions cannot be overriden; use 'public' instead}} {{3-7=public}}
-  open var nonObjcOpenVar: Int { 3 }  // expected-error {{non-@objc properties in extensions cannot be overriden; use 'public' instead}} {{3-7=public}}
-  @objc open func objcOpenMethod() { } // No error
-  @objc open var objcOpenVar: Int { 3 } // No error
-}
-
-@objcMembers
-open class ValidOpenExtension { }
-extension ValidOpenExtension {
-    open func objcOpenMethod() { } // No error
-    open var objcOpenVar: Int { 3 } // No error
-}
-

test/attr/open_objc.swift

@@ -0,0 +1,37 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-typecheck-verify-swift -sdk %clang-importer-sdk -I %t
+// REQUIRES: objc_interop
+
+import Foundation
+
+open class InvalidOpenExtension {
+  open func openMethod() { } // No warning: Pure Swift methods can be open inside the class declaration.
+  open var openVar: Int { 3 } // No warning: Pure Swift properties can be open inside the class declaration.
+}
+extension InvalidOpenExtension {
+  open func nonObjcOpenMethod() { } // expected-warning {{non-'@objc' methods in extensions cannot be overridden; use 'public' instead}} {{3-7=public}}
+  open var nonObjcOpenVar: Int { 3 }  // expected-warning {{non-'@objc' properties in extensions cannot be overridden; use 'public' instead}} {{3-7=public}}
+  @objc open func objcOpenMethod() { } // No warning: @objc methods can be open inside extensions. 
+  @objc open var objcOpenVar: Int { 3 } // No warning: @objc methods can be open inside extensions. 
+}
+
+// For extensions with access level less than open, '`open` modifier conflicts with...' warning will always precede the 'non-@objc member...' warning. 
+// For extensions with open access level, invalid open extension error will precede the 'non-@objc member...' warning. 
+public extension InvalidOpenExtension { 
+    open func nonObjcOpenMethod2() { } // expected-warning {{'open' modifier conflicts with extension's default access of 'public'}}
+    open var nonObjcOpenVar2: Int { 3 } // expected-warning {{'open' modifier conflicts with extension's default access of 'public'}}
+    @objc open func objcOpenMethod2() { } // expected-warning {{'open' modifier conflicts with extension's default access of 'public'}}
+    @objc open var objcOpenVar2: Int { 3 } // expected-warning {{'open' modifier conflicts with extension's default access of 'public'}}
+}
+
+@objcMembers
+open class ValidOpenExtension { }
+extension ValidOpenExtension {
+    open func objcOpenMethod() { } // No warning: This declaration is implicitly @objc
+    open var objcOpenVar: Int { 3 } // No warning: This declaration is implicitly @objc
+}
+
+public extension ValidOpenExtension { 
+    open func objcOpenMethod2() { } // expected-warning {{'open' modifier conflicts with extension's default access of 'public'}}
+    open var objcOpenVar2: Int { 3 } // expected-warning {{'open' modifier conflicts with extension's default access of 'public'}}
+}