Allow Deriving Type Witnesses Across Files

lib/Sema/DerivedConformanceCaseIterable.cpp

@@ -113,9 +113,6 @@ ValueDecl *DerivedConformance::deriveCaseIterable(ValueDecl *requirement) {
 }
 
 Type DerivedConformance::deriveCaseIterable(AssociatedTypeDecl *assocType) {
-  if (checkAndDiagnoseDisallowedContext(assocType))
-    return nullptr;
-
   // Check that we can actually derive CaseIterable for this type.
   if (!canDeriveConformance(Nominal))
     return nullptr;

lib/Sema/DerivedConformanceDifferentiable.cpp

@@ -895,9 +895,6 @@ DerivedConformance::deriveDifferentiable(AssociatedTypeDecl *requirement) {
                            diag::broken_differentiable_requirement);
     return std::make_pair(nullptr, nullptr);
   }
-  // Diagnose conformances in disallowed contexts.
-  if (checkAndDiagnoseDisallowedContext(requirement))
-    return std::make_pair(nullptr, nullptr);
 
   // Start an error diagnostic before attempting derivation.
   // If derivation succeeds, cancel the diagnostic.

test/AutoDiff/Sema/DerivedConformances/Inputs/class_differentiable_other_module.swift

@@ -1,9 +1,9 @@
 import _Differentiation
 
-// expected-note @+1 {{type declared here}}
+// expected-note @+1 2 {{type declared here}}
 class OtherFileNonconforming {}
 
-// expected-note @+1 {{type declared here}}
+// expected-note @+1 2 {{type declared here}}
 class GenericOtherFileNonconforming<T: Differentiable> {
   var x: T
 }

test/AutoDiff/Sema/DerivedConformances/Inputs/struct_differentiable_other_module.swift

@@ -1,9 +1,9 @@
 import _Differentiation
 
-// expected-note @+1 {{type declared here}}
+// expected-note @+1 2 {{type declared here}}
 struct OtherFileNonconforming {}
 
-// expected-note @+1 {{type declared here}}
+// expected-note @+1 2 {{type declared here}}
 struct GenericOtherFileNonconforming<T: Differentiable> {
   var x: T
 }

test/AutoDiff/Sema/DerivedConformances/class_differentiable.swift

@@ -570,10 +570,8 @@ class WrappedProperties: Differentiable {
 
 // Test derived conformances in disallowed contexts.
 
-// expected-error @+2 {{type 'OtherFileNonconforming' does not conform to protocol 'Differentiable'}}
-// expected-error @+1 {{implementation of 'Differentiable' cannot be automatically synthesized in an extension in a different file to the type}}
+// expected-error @+1 2 {{implementation of 'Differentiable' cannot be automatically synthesized in an extension in a different file to the type}}
 extension OtherFileNonconforming: Differentiable {}
 
-// expected-error @+2 {{type 'GenericOtherFileNonconforming<T>' does not conform to protocol 'Differentiable'}}
-// expected-error @+1 {{implementation of 'Differentiable' cannot be automatically synthesized in an extension in a different file to the type}}
+// expected-error @+1 2 {{implementation of 'Differentiable' cannot be automatically synthesized in an extension in a different file to the type}}
 extension GenericOtherFileNonconforming: Differentiable {}

test/AutoDiff/Sema/DerivedConformances/struct_differentiable.swift

@@ -383,10 +383,8 @@ struct WrappedProperties: Differentiable {
 
 // Verify that cross-file derived conformances are disallowed.
 
-// expected-error @+2 {{type 'OtherFileNonconforming' does not conform to protocol 'Differentiable'}}
-// expected-error @+1 {{implementation of 'Differentiable' cannot be automatically synthesized in an extension in a different file to the type}}
+// expected-error @+1 2 {{implementation of 'Differentiable' cannot be automatically synthesized in an extension in a different file to the type}}
 extension OtherFileNonconforming: Differentiable {}
 
-// expected-error @+2 {{type 'GenericOtherFileNonconforming<T>' does not conform to protocol 'Differentiable'}}
-// expected-error @+1 {{implementation of 'Differentiable' cannot be automatically synthesized in an extension in a different file to the type}}
+// expected-error @+1 2 {{implementation of 'Differentiable' cannot be automatically synthesized in an extension in a different file to the type}}
 extension GenericOtherFileNonconforming: Differentiable {}

test/Sema/Inputs/enum_conformance_synthesis_other.swift

@@ -29,3 +29,7 @@ extension ImpliedMain: ImplierMain {}
 enum ImpliedOther: ImplierOther {
     case a(Int)
 }
+
+enum CaseIterableAcrossFiles {
+  case A
+}

test/Sema/enum_conformance_synthesis.swift

@@ -224,7 +224,12 @@ enum Complex2 {
 }
 extension Complex2 : Hashable {}
 extension Complex2 : CaseIterable {}  // expected-error {{type 'Complex2' does not conform to protocol 'CaseIterable'}}
-extension FromOtherFile: CaseIterable {} // expected-error {{cannot be automatically synthesized in an extension in a different file to the type}} expected-error {{does not conform to protocol 'CaseIterable'}}
+extension FromOtherFile: CaseIterable {} // expected-error {{cannot be automatically synthesized in an extension in a different file to the type}}
+extension CaseIterableAcrossFiles: CaseIterable {
+  public static var allCases: [CaseIterableAcrossFiles] {
+    return [ .A ]
+  }
+}
 
 // No explicit conformance and it cannot be derived.
 enum NotExplicitlyHashableAndCannotDerive {