AST: Fix MemberImportVisibility handling of @_exported imports

lib/AST/NameLookup.cpp

@@ -2292,46 +2292,15 @@ ObjCCategoryNameMap ClassDecl::getObjCCategoryNameMap() {
                            ObjCCategoryNameMap());
 }
 
-static bool missingExplicitImportForMemberDecl(const DeclContext *dc,
-                                               ValueDecl *decl) {
+static bool missingImportForMemberDecl(const DeclContext *dc, ValueDecl *decl) {
   // Only require explicit imports for members when MemberImportVisibility is
   // enabled.
-  if (!dc->getASTContext().LangOpts.hasFeature(Feature::MemberImportVisibility))
+  auto &ctx = dc->getASTContext();
+  if (!ctx.LangOpts.hasFeature(Feature::MemberImportVisibility))
     return false;
 
-  // If the decl is in the same module, no import is required.
   auto declModule = decl->getDeclContext()->getParentModule();
-  if (declModule == dc->getParentModule())
-    return false;
-
-  // Source files are not expected to contain an import for the clang header
-  // module.
-  if (auto *loader = dc->getASTContext().getClangModuleLoader()) {
-    if (declModule == loader->getImportedHeaderModule())
-      return false;
-  }
-
-  // Only require an import in the context of user authored source file.
-  auto sf = dc->getParentSourceFile();
-  if (!sf)
-    return false;
-
-  switch (sf->Kind) {
-  case SourceFileKind::SIL:
-  case SourceFileKind::Interface:
-  case SourceFileKind::MacroExpansion:
-  case SourceFileKind::DefaultArgument:
-    return false;
-  case SourceFileKind::Library:
-  case SourceFileKind::Main:
-    break;
-  }
-
-  // If we've found an import, we're done.
-  if (decl->findImport(dc))
-    return false;
-
-  return true;
+  return !ctx.getImportCache().isImportedBy(declModule, dc);
 }
 
 /// Determine whether the given declaration is an acceptable lookup
@@ -2368,7 +2337,7 @@ static bool isAcceptableLookupResult(const DeclContext *dc,
   // Check that there is some import in the originating context that makes this
   // decl visible.
   if (!(options & NL_IgnoreMissingImports)) {
-    if (missingExplicitImportForMemberDecl(dc, decl))
+    if (missingImportForMemberDecl(dc, decl))
       return false;
   }
 

test/NameLookup/Inputs/MemberImportVisibility/members_A.swift

@@ -31,3 +31,17 @@ extension Y {
 public enum EnumInA {
   case caseInA
 }
+
+open class BaseClassInA {
+  open func methodInA() {}
+}
+
+public protocol ProtocolInA {
+  func defaultedRequirementInA()
+  func defaultedRequirementInB()
+  func defaultedRequirementInC()
+}
+
+extension ProtocolInA {
+  public func defaultedRequirementInA() { }
+}

test/NameLookup/Inputs/MemberImportVisibility/members_B.swift

@@ -27,3 +27,11 @@ public enum EnumInB {
 package enum EnumInB_package {
   case caseInB
 }
+
+open class DerivedClassInB: BaseClassInA {
+  open func methodInB() {}
+}
+
+extension ProtocolInA {
+  public func defaultedRequirementInB() { }
+}

test/NameLookup/Inputs/MemberImportVisibility/members_C.swift

@@ -21,3 +21,11 @@ extension Y {
 public enum EnumInC {
   case caseInC
 }
+
+open class DerivedClassInC: DerivedClassInB {
+  open func methodInC() {}
+}
+
+extension ProtocolInA {
+  public func defaultedRequirementInC() { }
+}

test/NameLookup/members_transitive.swift

@@ -67,3 +67,11 @@ func testTopLevelTypes() {
   _ = EnumInB_package.self // expected-error{{cannot find 'EnumInB_package' in scope}}
   _ = EnumInC.self
 }
+
+class DerivedFromClassInC: DerivedClassInC {
+  override func methodInA() {}
+  override func methodInB() {} // expected-member-visibility-error{{method does not override any method from its superclass}}
+  override func methodInC() {}
+}
+
+struct ConformsToProtocolInA: ProtocolInA {} // expected-member-visibility-error{{type 'ConformsToProtocolInA' does not conform to protocol 'ProtocolInA'}}

test/NameLookup/members_transitive_multifile.swift

@@ -9,15 +9,20 @@
 
 //--- main.swift
 
-// expected-member-visibility-note@+3 {{add import of module 'members_A'}}{{1-1=@_implementationOnly import members_A\n}}
-// expected-member-visibility-note@+2 {{add import of module 'members_B'}}{{1-1=@_exported import members_B\n}}
+// expected-member-visibility-note@+2 {{add import of module 'members_A'}}{{1-1=@_implementationOnly import members_A\n}}
 // expected-member-visibility-note@+1 {{add import of module 'members_C'}}{{1-1=@_weakLinked @_spiOnly import members_C\n}}
-func testMembersWithContextualBase() {
+func testMembersWithInferredContextualBase() {
   takesEnumInA(.caseInA) // expected-member-visibility-error{{enum case 'caseInA' is not available due to missing import of defining module 'members_A'}}
-  takesEnumInB(.caseInB) // expected-member-visibility-error{{enum case 'caseInB' is not available due to missing import of defining module 'members_B'}}
+  takesEnumInB(.caseInB)
   takesEnumInC(.caseInC) // expected-member-visibility-error{{enum case 'caseInC' is not available due to missing import of defining module 'members_C'}}
 }
 
+func testQualifiedMembers() {
+  takesEnumInA(EnumInA.caseInA) // expected-error{{cannot find 'EnumInA' in scope; did you mean 'EnumInB'?}}
+  takesEnumInB(EnumInB.caseInB)
+  takesEnumInC(EnumInC.caseInC) // expected-error{{cannot find 'EnumInC' in scope; did you mean 'EnumInB'?}}
+}
+
 //--- A.swift
 
 @_implementationOnly import members_A

test/NameLookup/members_transitive_underlying_clang.swift

@@ -2,14 +2,13 @@
 // RUN: split-file %s %t
 // RUN: %target-swift-frontend -typecheck -primary-file %t/Primary.swift %t/Other.swift -I %S/Inputs/MemberImportVisibility -module-name Underlying -verify -swift-version 5
 // RUN: %target-swift-frontend -typecheck -primary-file %t/Primary.swift %t/Other.swift -I %S/Inputs/MemberImportVisibility -module-name Underlying -verify -swift-version 6
-// RUN: %target-swift-frontend -typecheck -primary-file %t/Primary.swift %t/Other.swift -I %S/Inputs/MemberImportVisibility -module-name Underlying -verify -swift-version 5 -enable-experimental-feature MemberImportVisibility -verify-additional-prefix member-visibility-
+// RUN: %target-swift-frontend -typecheck -primary-file %t/Primary.swift %t/Other.swift -I %S/Inputs/MemberImportVisibility -module-name Underlying -verify -swift-version 5 -enable-experimental-feature MemberImportVisibility
 
 //--- Other.swift
 @_exported import Underlying
 
 //--- Primary.swift
 
-// expected-member-visibility-note@+1 {{add import of module 'Underlying'}}{{1-1=@_exported import Underlying\n}}
 func test(_ s: UnderlyingStruct) {
-  _ = s.a // expected-member-visibility-error {{property 'a' is not available due to missing import of defining module 'Underlying'}}
+  _ = s.a
 }