Sema: Report public conformances to non-publicly imported protocols

Exportability checking for non-public imports relies on classic
access-level checks for some of the work. However while conforming
to a local internal protocol from a public type is allow we should
disallow it for imported types, even when imported as internal.

Track exportability issues on conformances to protocols separately
from the general category. Use that information to improve the
diagnostics and report these issues for access-level on imports.

rdar://128420980

Author: xymus

PrivateLib

@@ -3648,7 +3648,8 @@ ERROR(decl_from_hidden_module,none,
       "cannot use %kind0 %select{here|as property wrapper here|"
       "as result builder here|"
       "in an extension with public or '@usableFromInline' members|"
-      "in an extension with conditional conformances}1; "
+      "in an extension with conditional conformances|"
+      "in a public or '@usableFromInline' conformance}1; "
       "%select{%2 has been imported as implementation-only|"
       "it is an SPI imported from %2|"
       "it is SPI|"
@@ -3662,7 +3663,8 @@ ERROR(typealias_desugars_to_type_from_hidden_module,none,
       "as property wrapper here|"
       "as result builder here|"
       "in an extension with public or '@usableFromInline' members|"
-      "in an extension with conditional conformances}3 "
+      "in an extension with conditional conformance|"
+      "in a public or '@usableFromInline' conformance}3 "
       "because %select{%4 has been imported as implementation-only|"
       "it is an SPI imported from %4|"
       "<<ERROR>>|"
@@ -3675,7 +3677,8 @@ ERROR(conformance_from_implementation_only_module,none,
       "cannot use conformance of %0 to %1 %select{here|as property wrapper here|"
       "as result builder here|"
       "in an extension with public or '@usableFromInline' members|"
-      "in an extension with conditional conformances}2; "
+      "in an extension with conditional conformances|"
+      "<<ERROR>>}2; "
       "%select{%3 has been imported as implementation-only|"
       "the conformance is declared as SPI in %3|"
       "the conformance is declared as SPI|"

include/swift/AST/DiagnosticsSema.def

@@ -248,11 +248,22 @@ static bool diagnoseValueDeclRefExportability(SourceLoc loc, const ValueDecl *D,
   }
 
   // Access levels from imports are reported with the others access levels.
-  // Except for extensions, we report them here.
-  if (originKind == DisallowedOriginKind::NonPublicImport &&
-      reason != ExportabilityReason::ExtensionWithPublicMembers &&
-      reason != ExportabilityReason::ExtensionWithConditionalConformances)
-    return false;
+  // Except for extensions and protocol conformances, we report them here.
+  if (originKind == DisallowedOriginKind::NonPublicImport) {
+    bool reportHere = [&] {
+      switch (*reason) {
+        case ExportabilityReason::ExtensionWithPublicMembers:
+        case ExportabilityReason::ExtensionWithConditionalConformances:
+          return true;
+        case ExportabilityReason::Inheritance:
+          return isa<ProtocolDecl>(D);
+        default:
+          return false;
+      }
+    }();
+    if (!reportHere)
+      return false;
+  }
 
   if (ctx.LangOpts.EnableModuleApiImportRemarks &&
       import.has_value() && where.isExported() &&

lib/Sema/ResilienceDiagnostics.cpp

@@ -2259,7 +2259,7 @@ class DeclAvailabilityChecker : public DeclVisitor<DeclAvailabilityChecker> {
 
     for (TypeLoc inherited : nominal->getInherited().getEntries()) {
       checkType(inherited.getType(), inherited.getTypeRepr(), nominal,
-                ExportabilityReason::General, flags);
+                ExportabilityReason::Inheritance, flags);
     }
   }
 
@@ -2361,7 +2361,7 @@ class DeclAvailabilityChecker : public DeclVisitor<DeclAvailabilityChecker> {
     // must be exported.
     for (TypeLoc inherited : ED->getInherited().getEntries()) {
       checkType(inherited.getType(), inherited.getTypeRepr(), ED,
-                ExportabilityReason::General,
+                ExportabilityReason::Inheritance,
                 DeclAvailabilityFlag::AllowPotentiallyUnavailableProtocol);
     }
 

lib/Sema/TypeCheckAccess.cpp

@@ -72,7 +72,8 @@ enum class ExportabilityReason : unsigned {
   PropertyWrapper,
   ResultBuilder,
   ExtensionWithPublicMembers,
-  ExtensionWithConditionalConformances
+  ExtensionWithConditionalConformances,
+  Inheritance
 };
 
 /// A description of the restrictions on what declarations can be referenced

lib/Sema/TypeCheckAvailability.h

@@ -0,0 +1,70 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend -emit-module -o %t/NormalLibrary.swiftmodule \
+// RUN:  %S/Inputs/implementation-only-import-in-decls-public-helper.swift \
+// RUN:  -enable-library-evolution -swift-version 5
+
+// RUN: %target-swift-frontend -emit-module -o %t/BADLibrary.swiftmodule \
+// RUN:  %S/Inputs/implementation-only-import-in-decls-helper.swift -I %t \
+// RUN:  -enable-library-evolution -swift-version 5
+
+// RUN: %target-typecheck-verify-swift -I %t \
+// RUN:  -swift-version 5 -package-name pkg -enable-library-evolution
+// RUN: %target-typecheck-verify-swift -I %t \
+// RUN:  -swift-version 5 -package-name pkg
+
+internal import BADLibrary // expected-note 14 {{protocol 'BadProto' imported as 'internal' from 'BADLibrary' here}}
+// expected-note @-1 2 {{struct 'IntLike' imported as 'internal' from 'BADLibrary' here}}
+// expected-note @-2 2 {{class 'BadClass' imported as 'internal' from 'BADLibrary' here}}
+
+public protocol LocalProto {}
+
+public struct TestConformance: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+public struct TestConformanceComposition: LocalProto & BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+@usableFromInline struct TestConformanceUFI: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+public class TestConformanceClass: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+public enum TestConformanceEnum: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+public struct TestExtensionStruct {}
+extension TestExtensionStruct: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+package struct TestConformancePackage: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+package struct TestConformanceCompositionPackage: LocalProto & BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+@usableFromInline struct TestConformanceUFIPackage: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+package class TestConformanceClassPackage: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+package enum TestConformanceEnumPackage: BADLibrary.BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+package struct TestExtensionStructPackage {}
+extension TestExtensionStructPackage: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+/// Other inheritance types are covered by the classic access-level check.
+
+public class TestSubclass: BadClass { // expected-error {{class cannot be declared public because its superclass is internal}}
+// expected-note @-1 {{class 'BadClass' is imported by this file as 'internal' from 'BADLibrary'}}
+}
+
+public enum TestRawType: IntLike { // expected-error {{enum cannot be declared public because its raw type uses an internal type}}
+// expected-note @-1 {{struct 'IntLike' is imported by this file as 'internal' from 'BADLibrary'}}
+  case x = 1
+}
+
+public protocol TestRefinedProto: BadProto { // expected-error {{public protocol cannot refine an internal protocol}}
+// expected-note @-1 {{protocol 'BadProto' is imported by this file as 'internal' from 'BADLibrary'}}
+}
+
+package class TestSubclassPackage: BadClass { // expected-error {{class cannot be declared package because its superclass is internal}}
+// expected-note @-1 {{class 'BadClass' is imported by this file as 'internal' from 'BADLibrary'}}
+}
+
+package enum TestRawTypePackage: IntLike { // expected-error {{enum cannot be declared package because its raw type uses an internal type}}
+// expected-note @-1 {{struct 'IntLike' is imported by this file as 'internal' from 'BADLibrary'}}
+  case x = 1
+}
+
+package protocol TestRefinedProtoPackage: BadProto { // expected-error {{package protocol cannot refine an internal protocol}}
+// expected-note @-1 {{protocol 'BadProto' is imported by this file as 'internal' from 'BADLibrary'}}
+}

test/Sema/access-level-import-conforming-types.swift

@@ -24,11 +24,10 @@ public typealias ClazzAlias = Clazz
 public import Aliases
 internal import Original // expected-note 2 {{class 'Clazz' imported as 'internal' from 'Original' here}}
 
-// expected-error@+1 {{'ClazzAlias' aliases 'Original.Clazz' and cannot be used here because 'Original' was not imported publicly}}
+// expected-error@+1 {{'ClazzAlias' aliases 'Original.Clazz' and cannot be used for a conformance on a public, package or '@usableFromInline' type because 'Original' was not imported publicly}}
 public class InheritsFromClazzAlias: ClazzAlias {}
 
 @inlinable public func inlinableFunc() {
   // expected-error@+1 {{'ClazzAlias' aliases 'Original.Clazz' and cannot be used in an '@inlinable' function because 'Original' was not imported publicly}}
   _ = ClazzAlias.self
 }
-

test/Sema/access-level-import-typealias.swift

@@ -11,15 +11,14 @@ import NormalLibrary
 @_implementationOnly import BADLibrary
 // expected-warning @-1 {{'@_implementationOnly' is deprecated, use 'internal import' instead}}
 
-public struct TestConformance: BadProto {} // expected-error {{cannot use protocol 'BadProto' here; 'BADLibrary' has been imported as implementation-only}}
+public struct TestConformance: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' has been imported as implementation-only}}
 
-@usableFromInline struct TestConformanceUFI: BadProto {} // expected-error {{cannot use protocol 'BadProto' here; 'BADLibrary' has been imported as implementation-only}}
+@usableFromInline struct TestConformanceUFI: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' has been imported as implementation-only}}
 
 struct TestConformanceOkay: BadProto {} // ok
 
-public class TestConformanceClass: BadProto {} // expected-error {{cannot use protocol 'BadProto' here; 'BADLibrary' has been imported as implementation-only}}
-public enum TestConformanceEnum: BadProto {} // expected-error {{cannot use protocol 'BadProto' here; 'BADLibrary' has been imported as implementation-only}}
-
+public class TestConformanceClass: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' has been imported as implementation-only}}
+public enum TestConformanceEnum: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' has been imported as implementation-only}}
 
 public struct TestGenericParams<T: BadProto> {} // expected-error {{cannot use protocol 'BadProto' here; 'BADLibrary' has been imported as implementation-only}}
 
@@ -75,11 +74,11 @@ public protocol TestAssocTypeWhereClause {
   associatedtype Assoc: Collection where Assoc.Element: BadProto // expected-error {{cannot use protocol 'BadProto' here; 'BADLibrary' has been imported as implementation-only}}
 }
 
-public enum TestRawType: IntLike { // expected-error {{cannot use struct 'IntLike' here; 'BADLibrary' has been imported as implementation-only}}
+public enum TestRawType: IntLike { // expected-error {{cannot use struct 'IntLike' in a public or '@usableFromInline' conformance; 'BADLibrary' has been imported as implementation-only}}
   case x = 1
 }
 
-public class TestSubclass: BadClass { // expected-error {{cannot use class 'BadClass' here; 'BADLibrary' has been imported as implementation-only}}
+public class TestSubclass: BadClass { // expected-error {{cannot use class 'BadClass' in a public or '@usableFromInline' conformance; 'BADLibrary' has been imported as implementation-only}}
 }
 
 public typealias TestUnderlying = BadStruct // expected-error {{cannot use struct 'BadStruct' here; 'BADLibrary' has been imported as implementation-only}}
@@ -121,7 +120,7 @@ extension Array where Element == BadStruct {
   subscript(okay _: Int) -> Int { 0 } // okay
 }
 
-extension Int: @retroactive BadProto {} // expected-error {{cannot use protocol 'BadProto' here; 'BADLibrary' has been imported as implementation-only}}
+extension Int: @retroactive BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' has been imported as implementation-only}}
 struct TestExtensionConformanceOkay {}
 extension TestExtensionConformanceOkay: BadProto {} // okay
 

test/Sema/implementation-only-import-in-decls.swift

@@ -0,0 +1,67 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend -emit-module -o %t/NormalLibrary.swiftmodule \
+// RUN:  %S/Inputs/implementation-only-import-in-decls-public-helper.swift \
+// RUN:  -enable-library-evolution -swift-version 5
+
+// RUN: %target-swift-frontend -emit-module -o %t/BADLibrary.swiftmodule \
+// RUN:  %S/Inputs/implementation-only-import-in-decls-helper.swift -I %t \
+// RUN:  -enable-library-evolution -swift-version 5
+
+// RUN: %target-typecheck-verify-swift -I %t \
+// RUN:  -swift-version 5 -package-name pkg -enable-library-evolution
+// RUN: %target-typecheck-verify-swift -I %t \
+// RUN:  -swift-version 5 -package-name pkg
+
+package import BADLibrary // expected-note 9 {{protocol 'BadProto' imported as 'package' from 'BADLibrary' here}}
+// expected-note @-1 {{struct 'IntLike' imported as 'package' from 'BADLibrary' here}}
+// expected-note @-2 {{class 'BadClass' imported as 'package' from 'BADLibrary' here}}
+
+public protocol LocalProto {}
+
+public struct TestConformance: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+public struct TestConformanceComposition: LocalProto & BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+@usableFromInline struct TestConformanceUFI: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+public class TestConformanceClass: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+public enum TestConformanceEnum: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+public struct TestExtensionStruct {}
+extension TestExtensionStruct: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+package struct TestConformancePackage: BadProto {}
+package struct TestConformanceCompositionPackage: LocalProto & BadProto {}
+
+@usableFromInline struct TestConformanceUFIPackage: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+package class TestConformanceClassPackage: BadProto {}
+package enum TestConformanceEnumPackage: BADLibrary.BadProto {}
+
+package struct TestExtensionStructPackage {}
+extension TestExtensionStructPackage: BadProto {} // expected-error {{cannot use protocol 'BadProto' in a public or '@usableFromInline' conformance; 'BADLibrary' was not imported publicly}}
+
+/// Other inheritance types are covered by the classic access-level check.
+
+public class TestSubclass: BadClass { // expected-error {{class cannot be declared public because its superclass is package}}
+// expected-note @-1 {{class 'BadClass' is imported by this file as 'package' from 'BADLibrary'}}
+}
+
+public enum TestRawType: IntLike { // expected-error {{enum cannot be declared public because its raw type uses a package type}}
+// expected-note @-1 {{struct 'IntLike' is imported by this file as 'package' from 'BADLibrary'}}
+  case x = 1
+}
+
+public protocol TestRefinedProto: BadProto { // expected-error {{public protocol cannot refine a package protocol}}
+// expected-note @-1 {{protocol 'BadProto' is imported by this file as 'package' from 'BADLibrary'}}
+}
+
+package class TestSubclassPackage: BadClass {
+}
+
+package enum TestRawTypePackage: IntLike {
+  case x = 1
+}
+
+package protocol TestRefinedProtoPackage: BadProto {
+}