AST/Sema: Make MemberImportVisibility a migratable feature

include/swift/AST/DiagnosticEngine.h

@@ -475,9 +475,6 @@ namespace swift {
 
     static const char *fixItStringFor(const FixItID id);
 
-    /// Get the best location where an 'import' fixit might be offered.
-    SourceLoc getBestAddImportFixItLoc(const Decl *Member) const;
-
     /// Add a token-based replacement fix-it to the currently-active
     /// diagnostic.
     template <typename... ArgTypes>
@@ -1195,11 +1192,7 @@ namespace swift {
     SourceLoc getDefaultDiagnosticLoc() const {
       return bufferIndirectlyCausingDiagnostic;
     }
-    SourceLoc getBestAddImportFixItLoc(const Decl *Member,
-                                       SourceFile *sourceFile) const;
-    SourceLoc getBestAddImportFixItLoc(const Decl *Member) const {
-      return getBestAddImportFixItLoc(Member, nullptr);
-    }
+    SourceLoc getBestAddImportFixItLoc(SourceFile *sf) const;
   };
 
   inline SourceManager &InFlightDiagnostic::getSourceManager() {

include/swift/AST/DiagnosticGroups.def

@@ -49,6 +49,7 @@ GROUP(ErrorInFutureSwiftVersion, "error-in-future-swift-version")
 GROUP(ExistentialAny, "existential-any")
 GROUP(ExistentialMemberAccess, "existential-member-access-limitations")
 GROUP(IsolatedConformances, "isolated-conformances")
+GROUP(MemberImportVisibility, "member-import-visibility")
 GROUP(MultipleInheritance, "multiple-inheritance")
 GROUP(MutableGlobalVariable, "mutable-global-variable")
 GROUP(NominalTypes, "nominal-types")

include/swift/AST/DiagnosticsSema.def

@@ -167,16 +167,21 @@ ERROR(init_candidate_inaccessible,none,
       "'%select{private|fileprivate|internal|package|@_spi|@_spi}1' protection level",
       (Type, AccessLevel))
 
-ERROR(candidate_from_missing_import,none,
+GROUPED_ERROR(member_from_missing_import,MemberImportVisibility,none,
       "%kind0 is not available due to missing import of defining module %1",
       (const ValueDecl *, const ModuleDecl *))
-ERROR(candidate_from_missing_imports_2_or_more,none,
+GROUPED_ERROR(member_from_missing_imports_2_or_more,MemberImportVisibility,none,
       "%kind0 is not available due to missing imports of defining modules "
       "%2%select{ and|, }1 %3%select{|, and others}1",
       (const ValueDecl *, bool, const ModuleDecl *, const ModuleDecl *))
 NOTE(candidate_add_import,none,
      "add import of module %0", (const ModuleDecl *))
 
+GROUPED_WARNING(add_required_import_for_member,MemberImportVisibility,none,
+     "import of module %0 is required", (const ModuleDecl *))
+NOTE(decl_from_module_used_here,none,
+     "%kind0 from %1 used here", (const ValueDecl *, const ModuleDecl *))
+
 ERROR(cannot_pass_rvalue_mutating_subelement,none,
       "cannot use mutating member on immutable value: %0",
       (StringRef))

include/swift/Basic/Features.def

@@ -287,7 +287,7 @@ UPCOMING_FEATURE(GlobalActorIsolatedTypesUsability, 0434, 6)
 // Swift 7
 MIGRATABLE_UPCOMING_FEATURE(ExistentialAny, 335, 7)
 UPCOMING_FEATURE(InternalImportsByDefault, 409, 7)
-UPCOMING_FEATURE(MemberImportVisibility, 444, 7)
+MIGRATABLE_UPCOMING_FEATURE(MemberImportVisibility, 444, 7)
 MIGRATABLE_UPCOMING_FEATURE(InferIsolatedConformances, 470, 7)
 MIGRATABLE_UPCOMING_FEATURE(NonisolatedNonsendingByDefault, 461, 7)
 

include/swift/Basic/LangOptions.h

@@ -873,13 +873,17 @@ namespace swift {
 
     /// Returns whether the given feature is enabled.
     ///
-    /// If allowMigration is set, also returns true when the feature has been enabled for migration.
+    /// If allowMigration is set, also returns true when the feature has been
+    /// enabled for migration.
     bool hasFeature(Feature feature, bool allowMigration = false) const;
 
     /// Returns whether a feature with the given name is enabled. Returns
     /// `false` if a feature by this name is not known.
     bool hasFeature(llvm::StringRef featureName) const;
 
+    /// Returns whether the given feature is enabled for migration.
+    bool isMigratingToFeature(Feature feature) const;
+
     /// Enables the given feature (enables in migration mode if `forMigration`
     /// is `true`).
     void enableFeature(Feature feature, bool forMigration = false);

lib/AST/DiagnosticEngine.cpp

@@ -313,18 +313,12 @@ InFlightDiagnostic::fixItReplaceChars(SourceLoc Start, SourceLoc End,
   return *this;
 }
 
-SourceLoc
-DiagnosticEngine::getBestAddImportFixItLoc(const Decl *Member,
-                                           SourceFile *sourceFile) const {
+SourceLoc DiagnosticEngine::getBestAddImportFixItLoc(SourceFile *SF) const {
   auto &SM = SourceMgr;
 
   SourceLoc bestLoc;
-
-  auto SF =
-      sourceFile ? sourceFile : Member->getDeclContext()->getParentSourceFile();
-  if (!SF) {
+  if (!SF)
     return bestLoc;
-  }
 
   for (auto item : SF->getTopLevelItems()) {
     // If we found an import declaration, we want to insert after it.
@@ -356,30 +350,21 @@ DiagnosticEngine::getBestAddImportFixItLoc(const Decl *Member,
 
 InFlightDiagnostic &InFlightDiagnostic::fixItAddImport(StringRef ModuleName) {
   assert(IsActive && "Cannot modify an inactive diagnostic");
-  auto Member = Engine->ActiveDiagnostic->getDecl();
-  SourceLoc bestLoc = Engine->getBestAddImportFixItLoc(Member);
-
-  if (bestLoc.isValid()) {
-    llvm::SmallString<64> importText;
-
-    // @_spi imports.
-    if (Member->isSPI()) {
-      auto spiGroups = Member->getSPIGroups();
-      if (!spiGroups.empty()) {
-        importText += "@_spi(";
-        importText += spiGroups[0].str();
-        importText += ") ";
-      }
-    }
+  auto decl = Engine->ActiveDiagnostic->getDecl();
+  if (!decl)
+    return *this;
 
-    importText += "import ";
-    importText += ModuleName;
-    importText += "\n";
+  auto bestLoc = Engine->getBestAddImportFixItLoc(
+      decl->getDeclContext()->getOutermostParentSourceFile());
+  if (!bestLoc.isValid())
+    return *this;
 
-    return fixItInsert(bestLoc, importText);
-  }
+  llvm::SmallString<64> importText;
+  importText += "import ";
+  importText += ModuleName;
+  importText += "\n";
 
-  return *this;
+  return fixItInsert(bestLoc, importText);
 }
 
 InFlightDiagnostic &

lib/AST/NameLookup.cpp

@@ -2371,7 +2371,9 @@ ObjCCategoryNameMap ClassDecl::getObjCCategoryNameMap() {
 /// the given context.
 static bool shouldRequireImportsInContext(const DeclContext *lookupContext) {
   auto &ctx = lookupContext->getASTContext();
-  if (!ctx.LangOpts.hasFeature(Feature::MemberImportVisibility))
+
+  if (!ctx.LangOpts.hasFeature(Feature::MemberImportVisibility,
+                               /*allowMigration=*/true))
     return false;
 
   // Code outside of the main module (which is often synthesized) isn't subject
@@ -3591,7 +3593,8 @@ ExtendedNominalRequest::evaluate(Evaluator &evaluator,
   // inaccessible due to missing imports. The missing imports will be diagnosed
   // elsewhere.
   if (referenced.first.empty() &&
-      ctx.LangOpts.hasFeature(Feature::MemberImportVisibility)) {
+      ctx.LangOpts.hasFeature(Feature::MemberImportVisibility,
+                              /*allowMigration=*/true)) {
     options |= DirectlyReferencedTypeLookupFlags::IgnoreMissingImports;
     referenced = directReferencesForTypeRepr(evaluator, ctx, typeRepr,
                                              ext->getParent(), options);

lib/Basic/LangOptions.cpp

@@ -340,8 +340,10 @@ bool LangOptions::hasFeature(Feature feature, bool allowMigration) const {
   if (state.isEnabled())
     return true;
 
-  if (auto version = feature.getLanguageVersion())
-    return isSwiftVersionAtLeast(*version);
+  if (auto version = feature.getLanguageVersion()) {
+    if (isSwiftVersionAtLeast(*version))
+      return true;
+  }
 
   if (allowMigration && state.isEnabledForMigration())
     return true;
@@ -361,6 +363,10 @@ bool LangOptions::hasFeature(llvm::StringRef featureName) const {
   return false;
 }
 
+bool LangOptions::isMigratingToFeature(Feature feature) const {
+  return featureStates.getState(feature).isEnabledForMigration();
+}
+
 void LangOptions::enableFeature(Feature feature, bool forMigration) {
   if (forMigration) {
     ASSERT(feature.isMigratable());

lib/Basic/SupportedFeatures.cpp

@@ -35,6 +35,8 @@ static std::vector<DiagGroupID> migratableCategories(Feature feature) {
       return { DiagGroupID::ExistentialAny };
     case Feature::InnerKind::InferIsolatedConformances:
       return { DiagGroupID::IsolatedConformances };
+    case Feature::InnerKind::MemberImportVisibility:
+      return { DiagGroupID::MemberImportVisibility };
     case Feature::InnerKind::NonisolatedNonsendingByDefault:
       return { DiagGroupID::NonisolatedNonsendingByDefault };
     case Feature::InnerKind::StrictMemorySafety:

lib/Sema/MiscDiagnostics.cpp

@@ -6322,7 +6322,8 @@ static void diagnoseMissingMemberImports(const Expr *E, const DeclContext *DC) {
   };
 
   auto &ctx = DC->getASTContext();
-  if (!ctx.LangOpts.hasFeature(Feature::MemberImportVisibility))
+  if (!ctx.LangOpts.hasFeature(Feature::MemberImportVisibility,
+                               /*allowMigration=*/true))
     return;
 
   DiagnoseWalker walker(DC);

lib/Sema/ResilienceDiagnostics.cpp

@@ -279,7 +279,9 @@ static bool diagnoseValueDeclRefExportability(SourceLoc loc, const ValueDecl *D,
   // Some diagnostics emitted with the `MemberImportVisibility` feature enabled
   // subsume these diagnostics.
   if (originKind == DisallowedOriginKind::MissingImport &&
-      ctx.LangOpts.hasFeature(Feature::MemberImportVisibility) && SF)
+      ctx.LangOpts.hasFeature(Feature::MemberImportVisibility,
+                              /*allowMigration=*/true) &&
+      SF)
     return false;
 
   if (auto accessor = dyn_cast<AccessorDecl>(D)) {

lib/Sema/TypeCheckDeclOverride.cpp

@@ -1532,7 +1532,8 @@ bool swift::checkOverrides(ValueDecl *decl) {
 
   auto &ctx = decl->getASTContext();
   if (overridden.empty() &&
-      ctx.LangOpts.hasFeature(Feature::MemberImportVisibility)) {
+      ctx.LangOpts.hasFeature(Feature::MemberImportVisibility,
+                              /*allowMigration=*/true)) {
     // If we didn't find anything, try broadening the search by ignoring missing
     // imports.
     if (!checkPotentialOverrides(decl, overridden,
@@ -2529,7 +2530,8 @@ OverriddenDeclsRequest::evaluate(Evaluator &evaluator, ValueDecl *decl) const {
   // If we didn't find anything, try broadening the search by ignoring missing
   // imports.
   if (overridden.empty() &&
-      ctx.LangOpts.hasFeature(Feature::MemberImportVisibility)) {
+      ctx.LangOpts.hasFeature(Feature::MemberImportVisibility,
+                              /*allowMigration=*/true)) {
     overridden = computeOverriddenDecls(decl, true);
     if (!overridden.empty()) {
       auto first = overridden.front();