Don't force inlinable constructors to delegate in non-resilient code

lib/AST/Decl.cpp

@@ -5471,7 +5471,11 @@ ConstructorDecl::getDelegatingOrChainedInitKind(DiagnosticEngine *diags,
   // always delegating. This occurs if the struct type is not fixed layout,
   // and the constructor is either inlinable or defined in another module.
   if (Kind == BodyInitKind::None && isa<StructDecl>(NTD)) {
-    if (NTD->isFormallyResilient() &&
+    // Note: This is specifically not using isFormallyResilient. We relax this
+    // rule for structs in non-resilient modules so that they can have inlinable
+    // constructors, as long as those constructors don't reference private
+    // declarations.
+    if (NTD->isResilient() &&
         getResilienceExpansion() == ResilienceExpansion::Minimal) {
       Kind = BodyInitKind::Delegating;
 

lib/Sema/TypeCheckStmt.cpp

@@ -1620,9 +1620,12 @@ bool TypeChecker::typeCheckConstructorBodyUntil(ConstructorDecl *ctor,
     }
 
     // An inlinable constructor in a class must always be delegating,
-    // unless the class is formally '@_fixed_layout'.
-    if (!isDelegating &&
-        ClassD->isFormallyResilient() &&
+    // unless the class is '@_fixed_layout'.
+    // Note: This is specifically not using isFormallyResilient. We relax this
+    // rule for classes in non-resilient modules so that they can have inlinable
+    // constructors, as long as those constructors don't reference private
+    // declarations.
+    if (!isDelegating && ClassD->isResilient() &&
         ctor->getResilienceExpansion() == ResilienceExpansion::Minimal) {
       diagnose(ctor, diag::class_designated_init_inlineable_resilient,
                ClassD->getDeclaredInterfaceType(),

test/decl/init/resilience-cross-module.swift

@@ -0,0 +1,38 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend -emit-module -enable-resilience -emit-module-path=%t/resilient_struct.swiftmodule -module-name=resilient_struct %S/../../Inputs/resilient_struct.swift
+// RUN: %target-swift-frontend -emit-module -enable-resilience -emit-module-path=%t/resilient_protocol.swiftmodule -module-name=resilient_protocol %S/../../Inputs/resilient_protocol.swift
+
+// RUN: %target-swift-frontend -typecheck -swift-version 4 -verify -I %t %s
+// RUN: %target-swift-frontend -typecheck -swift-version 4 -verify -enable-resilience -I %t %s
+
+// RUN: %target-swift-frontend -typecheck -swift-version 5 -verify -I %t %s
+// RUN: %target-swift-frontend -typecheck -swift-version 5 -verify -enable-resilience -I %t %s
+
+import resilient_struct
+import resilient_protocol
+
+// Size is not @_fixed_layout, so we cannot define a new designated initializer
+extension Size {
+  init(ww: Int, hh: Int) {
+    self.w = ww
+    self.h = hh // expected-error {{'let' property 'h' may not be initialized directly; use "self.init(...)" or "self = ..." instead}}
+  }
+
+  // This is OK
+  init(www: Int, hhh: Int) {
+    self.init(w: www, h: hhh)
+  }
+
+  // This is OK
+  init(other: Size) {
+    self = other
+  }
+}
+
+// Protocol extension initializers are OK too
+extension OtherResilientProtocol {
+  public init(other: Self) {
+    self = other
+  }
+}

test/decl/init/resilience.swift

@@ -1,34 +1,9 @@
-// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend -typecheck -swift-version 4 -verify -enable-resilience %s -DRESILIENT
+// RUN: %target-swift-frontend -typecheck -swift-version 5 -verify -enable-resilience %s -DRESILIENT
 
-// RUN: %target-swift-frontend -emit-module -enable-resilience -emit-module-path=%t/resilient_struct.swiftmodule -module-name=resilient_struct %S/../../Inputs/resilient_struct.swift
-// RUN: %target-swift-frontend -emit-module -enable-resilience -emit-module-path=%t/resilient_protocol.swiftmodule -module-name=resilient_protocol %S/../../Inputs/resilient_protocol.swift
-
-// RUN: %target-swift-frontend -typecheck -swift-version 4 -verify -I %t %s
-// RUN: %target-swift-frontend -typecheck -swift-version 4 -verify -enable-resilience -I %t %s
-
-// RUN: %target-swift-frontend -typecheck -swift-version 5 -verify -I %t %s
-// RUN: %target-swift-frontend -typecheck -swift-version 5 -verify -enable-resilience -I %t %s
-
-import resilient_struct
-import resilient_protocol
-
-// Size is not @_fixed_layout, so we cannot define a new designated initializer
-extension Size {
-  init(ww: Int, hh: Int) {
-    self.w = ww
-    self.h = hh // expected-error {{'let' property 'h' may not be initialized directly; use "self.init(...)" or "self = ..." instead}}
-  }
-
-  // This is OK
-  init(www: Int, hhh: Int) {
-    self.init(w: www, h: hhh)
-  }
-
-  // This is OK
-  init(other: Size) {
-    self = other
-  }
-}
+// There should be no errors when run without resilience enabled.
+// RUN: %target-swift-frontend -typecheck -swift-version 4 %s
+// RUN: %target-swift-frontend -typecheck -swift-version 5 %s
 
 // Animal is not @_fixed_layout, so we cannot define an @_inlineable
 // designated initializer
@@ -86,10 +61,3 @@ extension Gadget {
     self.init()
   }
 }
-
-// Protocol extension initializers are OK too
-extension OtherResilientProtocol {
-  public init(other: Self) {
-    self = other
-  }
-}