Merge pull request #71518 from xymus/superfluously-public-import-fixes2

Sema: track use of public imports by more extensions

Author: xymus

lib/Sema/TypeCheckAccess.cpp

@@ -2360,6 +2360,32 @@ class DeclAvailabilityChecker : public DeclVisitor<DeclAvailabilityChecker> {
     Where = wasWhere.withExported(hasExportedMembers ||
                                   !ED->getInherited().empty());
     checkConstrainedExtensionRequirements(ED, hasExportedMembers);
+
+    if (!hasExportedMembers &&
+        !ED->getInherited().empty()) {
+      // If we haven't already visited the extended nominal visit it here.
+      // This logic is too wide but prevents false reports of an unused public
+      // import. We should instead check for public generic requirements
+      // similarly to ShouldPrintForModuleInterface::shouldPrint.
+      auto DC = Where.getDeclContext();
+      ImportAccessLevel import = extendedType->getImportAccessFrom(DC);
+      if (import.has_value()) {
+        auto SF = DC->getParentSourceFile();
+        if (SF)
+          SF->registerAccessLevelUsingImport(import.value(),
+                                             AccessLevel::Public);
+
+        auto &ctx = DC->getASTContext();
+        if (ctx.LangOpts.EnableModuleApiImportRemarks) {
+          ModuleDecl *importedVia = import->module.importedModule,
+                     *sourceModule = ED->getModuleContext();
+          ED->diagnose(diag::module_api_import,
+                       ED, importedVia, sourceModule,
+                       importedVia == sourceModule,
+                       /*isImplicit*/false);
+        }
+      }
+    }
   }
 
   void checkPrecedenceGroup(const PrecedenceGroupDecl *PGD,

test/Sema/superfluously-public-imports.swift

@@ -22,6 +22,7 @@
 // RUN: %target-swift-frontend -emit-module %t/ImportUsedInPackage.swift -o %t -I %t
 // RUN: %target-swift-frontend -emit-module %t/ExportedUnused.swift -o %t -I %t
 // RUN: %target-swift-frontend -emit-module %t/SPIOnlyUsedInSPI.swift -o %t -I %t
+// RUN: %target-swift-frontend -emit-module %t/RetroactiveConformance.swift -o %t -I %t
 
 /// Check diagnostics.
 // RUN: %target-swift-frontend -typecheck %t/Client.swift -I %t \
@@ -110,6 +111,11 @@ public func packageFunc() -> PackageType { return PackageType() }
 //--- SPIOnlyUsedInSPI.swift
 public struct ToUseFromSPI {}
 
+//--- RetroactiveConformance.swift
+public struct Extended {
+  public var count: Int { 42 }
+}
+
 //--- Client_Swift5.swift
 /// No diagnostics should be raised on the implicit access level.
 import UnusedImport // expected-error {{ambiguous implicit access level for import of 'UnusedImport'; it is imported as 'public' elsewhere}}
@@ -143,6 +149,7 @@ public import ImportUsedInPackage // expected-warning {{public import of 'Import
 
 @_exported public import ExportedUnused
 @_spiOnly public import SPIOnlyUsedInSPI
+public import RetroactiveConformance
 
 public func useInSignature(_ a: TypeUsedInSignature) {} // expected-remark {{struct 'TypeUsedInSignature' is imported via 'DepUsedInSignature'}}
 public func exportedTypeUseInSignature(_ a: ExportedType) {} // expected-remark {{struct 'ExportedType' is imported via 'Exporter', which reexports definition from 'Exportee'}}
@@ -228,6 +235,13 @@ package func packageFunc(a: PackageType = packageFunc()) {} // expected-remark {
 @_spi(X)
 public func spiFunc(a: ToUseFromSPI) {} // expected-remark {{struct 'ToUseFromSPI' is imported via 'SPIOnlyUsedInSPI'}}
 
+public protocol Countable {
+  var count: Int { get } // expected-remark {{struct 'Int' is imported via 'Swift'}}
+}
+
+extension Extended: Countable { // expected-remark {{struct 'Extended' is imported via 'RetroactiveConformance'}}
+}
+
 /// Tests for imports of clang modules.
 //--- module.modulemap
 module ClangSimpleUnused {