Merge pull request #38991 from mininny/diagnostic-for-non-objc-open-function-in-extension

[Diagnostics] Add diagnostic for non-objc functions declared as open inside extension

Author: xedin

include/swift/AST/DiagnosticsSema.def

@@ -1514,6 +1514,9 @@ 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'", ())
+WARNING(access_control_non_objc_open_member,none,
+      "non-'@objc' %0 in extensions cannot be overridden; use 'public' instead",
+      (DescriptiveDeclKind))
 
 ERROR(invalid_decl_attribute,none,
       "'%0' attribute cannot be applied to this declaration", (DeclAttribute))

lib/Sema/TypeCheckAttr.cpp

@@ -874,6 +874,19 @@ void AttributeChecker::visitAccessControlAttr(AccessControlAttr *attr) {
                  extAttr->getAccess())
           .fixItRemove(attr->getRange());
       }
+    } else {
+      if (auto VD = dyn_cast<ValueDecl>(D)) {
+        if (!isa<NominalTypeDecl>(VD)) {
+          // 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,
+                     VD->getDescriptiveKind())
+                .fixItReplace(attr->getRange(), "public");
+          }
+        }
+      }
     }
   }
 

test/attr/open_objc.swift

@@ -4,6 +4,48 @@
 
 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' instance method in extensions cannot be overridden; use 'public' instead}} {{3-7=public}}
+  open class func nonObjcOpenMethod() { } // expected-warning {{non-'@objc' class method in extensions cannot be overridden; use 'public' instead}} {{3-7=public}}
+  open var nonObjcOpenVar: Int { 3 }  // expected-warning {{non-'@objc' property in extensions cannot be overridden; use 'public' instead}} {{3-7=public}}
+  open subscript(_ index: Int) -> Int { 3 } // expected-warning {{non-'@objc' subscript in extensions cannot be overridden; use 'public' instead}} {{3-7=public}}
+  open convenience init(index: Int) { self.init() } // expected-error {{only classes and overridable class members can be declared 'open'; use 'public'}} // expected-warning {{non-'@objc' initializer in extensions cannot be overridden; use 'public' instead}}
+
+  @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. 
+
+  open class nonObjcClassDecl  { }
+  open enum nonObjcEnumDecl { case one } // expected-error {{only classes and overridable class members can be declared 'open'; use 'public'}} {{3-7=public}}
+}
+
+// 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 class func objcOpenMethod() { } // No warning: This declaration is implicitly @objc
+    open var objcOpenVar: Int { 3 } // No warning: This declaration is implicitly @objc
+    open subscript(_ index: Int) -> Int { 3 } // No warning: This declaration is implicitly @objc
+    open convenience init(index: Int) { self.init() } // expected-error {{only classes and overridable class members can be declared 'open'; use 'public'}}
+}
+
+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'}}
+}
+
 class InvalidOpenExtensionClass { }
 
 open extension InvalidOpenExtensionClass {  // expected-error {{extensions cannot be declared 'open'; declare individual members as 'open' instead}} {{1-6=}} {{3-3=public }} {{9-9=open }} {{9-9=open }} {{3-3=public }}