Merge pull request #70236 from DougGregor/required-inits-69965

Diagnose *all* cases where a subclass fails to override a required init

Author: DougGregor

lib/Sema/CodeSynthesis.cpp

@@ -826,6 +826,7 @@ createDesignatedInitOverride(ClassDecl *classDecl,
 static void diagnoseMissingRequiredInitializer(
               ClassDecl *classDecl,
               ConstructorDecl *superInitializer,
+              bool downgradeToWarning,
               ASTContext &ctx) {
   // Find the location at which we should insert the new initializer.
   SourceLoc insertionLoc;
@@ -906,6 +907,7 @@ static void diagnoseMissingRequiredInitializer(
   ctx.Diags.diagnose(insertionLoc, diag::required_initializer_missing,
                      superInitializer->getName(),
                      superInitializer->getDeclContext()->getDeclaredInterfaceType())
+    .warnUntilSwiftVersionIf(downgradeToWarning, 6)
     .fixItInsert(insertionLoc, initializerText);
 
   ctx.Diags.diagnose(findNonImplicitRequiredInit(superInitializer),
@@ -1172,10 +1174,11 @@ static void addImplicitInheritedConstructorsToClass(ClassDecl *decl) {
   bool defaultInitable =
       areAllStoredPropertiesDefaultInitializable(ctx.evaluator, decl);
 
-  // We can't define these overrides if we have any uninitialized
-  // stored properties.
-  if (!defaultInitable && !foundDesignatedInit)
-    return;
+  // In cases where we can't define any overrides, we used to suppress
+  // diagnostics about missing required initializers. Now we emit diagnostics,
+  // but downgrade them to warnings prior to Swift 6.
+  bool downgradeRequiredInitsToWarning =
+      !defaultInitable && !foundDesignatedInit;
 
   SmallVector<ConstructorDecl *, 4> nonOverriddenSuperclassCtors;
   collectNonOveriddenSuperclassInits(decl, nonOverriddenSuperclassCtors);
@@ -1187,8 +1190,10 @@ static void addImplicitInheritedConstructorsToClass(ClassDecl *decl) {
       if (superclassCtor->isRequired()) {
         assert(superclassCtor->isInheritable() &&
                "factory initializers cannot be 'required'");
-        if (!decl->inheritsSuperclassInitializers())
-          diagnoseMissingRequiredInitializer(decl, superclassCtor, ctx);
+        if (!decl->inheritsSuperclassInitializers()) {
+          diagnoseMissingRequiredInitializer(
+              decl, superclassCtor, downgradeRequiredInitsToWarning, ctx);
+        }
       }
       continue;
     }
@@ -1204,12 +1209,18 @@ static void addImplicitInheritedConstructorsToClass(ClassDecl *decl) {
 
     // Diagnose a missing override of a required initializer.
     if (superclassCtor->isRequired() && !inheritDesignatedInits) {
-      diagnoseMissingRequiredInitializer(decl, superclassCtor, ctx);
+      diagnoseMissingRequiredInitializer(
+          decl, superclassCtor, downgradeRequiredInitsToWarning, ctx);
       continue;
     }
 
     // A designated or required initializer has not been overridden.
 
+    // We can't define any overrides if we have any uninitialized
+    // stored properties.
+    if (!defaultInitable && !foundDesignatedInit)
+      continue;
+
     bool alreadyDeclared = false;
 
     auto results = decl->lookupDirect(DeclBaseName::createConstructor());

test/decl/class/inheritance_across_modules.swift

@@ -0,0 +1,20 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+
+// RUN: %target-swift-frontend -emit-module-path %t/MyModule.swiftmodule %t/Inputs/MyModule.swift
+
+// RUN: %target-swift-frontend -typecheck -verify -I %t %t/test.swift
+
+//--- Inputs/MyModule.swift
+open class MySuperclassA {
+  required public init() { }
+  internal init(boop: Bool) {}
+}
+
+//--- test.swift
+import MyModule
+
+class MySubclassA: MySuperclassA {
+// expected-warning{{'required' initializer 'init()' must be provided by subclass of 'MySuperclassA'; this is an error in Swift 6}}
+  var hi: String
+}

test/decl/protocol/special/coding/class_codable_inheritance_diagnostics.swift

@@ -63,6 +63,7 @@ class DecodableSuper : Decodable {
 
 // expected-note@+1 {{did you mean to override 'init(from:)'?}}{{+1:1-1=\noverride init(from decoder: Decoder) throws {\n    <#code#>\n\}}}
 class DecodableSubWithoutInitialValue : DecodableSuper { // expected-error {{class 'DecodableSubWithoutInitialValue' has no initializers}}
+// expected-warning{{'required' initializer 'init(from:)' must be provided by subclass of 'DecodableSuper'}}
   var value2: Int // expected-note {{stored property 'value2' without initial value prevents synthesized initializers}}
 }
 
@@ -78,6 +79,7 @@ class CodableSuper : Codable {
 
 // expected-note@+1 {{did you mean to override 'init(from:)' and 'encode(to:)'?}}{{+1:1-1=\noverride init(from decoder: Decoder) throws {\n    <#code#>\n\}\n\noverride func encode(to encoder: Encoder) throws {\n    <#code#>\n\}}}
 class CodableSubWithoutInitialValue : CodableSuper { // expected-error {{class 'CodableSubWithoutInitialValue' has no initializers}}
+  // expected-warning{{'required' initializer 'init(from:)' must be provided by subclass of 'CodableSuper'; this is an error in Swift 6}}
   var value2: Int // expected-note {{stored property 'value2' without initial value prevents synthesized initializers}}
 }
 
@@ -86,6 +88,7 @@ class CodableSubWithoutInitialValue : CodableSuper { // expected-error {{class '
 //
 // expected-note@+1 {{did you mean to override 'init(from:)'?}}{{+1:1-1=\noverride init(from decoder: Decoder) throws {\n    <#code#>\n\}}}
 class EncodableSubWithoutInitialValue : CodableSuper { // expected-error {{class 'EncodableSubWithoutInitialValue' has no initializers}}
+  // expected-warning{{'required' initializer 'init(from:)' must be provided by subclass of 'CodableSuper'; this is an error in Swift 6}}
   var value2: Int // expected-note {{stored property 'value2' without initial value prevents synthesized initializers}}
 
   override func encode(to: Encoder) throws {}