Sema: only mark the authoritative import as used in API

Author: xymus

lib/Sema/TypeCheckAccess.cpp

@@ -2507,15 +2507,9 @@ void swift::recordRequiredImportAccessLevelForDecl(
   if (definingModule == dc->getParentModule())
     return;
 
-  sf->registerRequiredAccessLevelForModule(definingModule, accessLevel);
-
   if (auto attributedImport = sf->getImportAccessLevel(definingModule)) {
     auto importedModule = attributedImport->module.importedModule;
-
-    // If the defining module is transitively imported, mark the responsible
-    // module as requiring the minimum access level too.
-    if (importedModule != definingModule)
-      sf->registerRequiredAccessLevelForModule(importedModule, accessLevel);
+    sf->registerRequiredAccessLevelForModule(importedModule, accessLevel);
 
     if (dc->getASTContext().LangOpts.EnableModuleApiImportRemarks)
       remark(*attributedImport);

test/Sema/authoritative-import-priority.swift

@@ -133,7 +133,7 @@ public func useTypesC(a: FarClangType) {}
 //--- ExportedClient_FileA.swift
 /// Prefer the defining module.
 public import NotLib // expected-warning {{public import of 'NotLib' was not used in public declarations or inlinable code}}
-public import LibCore
+public import LibCore // expected-warning {{public import of 'LibCore' was not used in public declarations or inlinable code}}
 public import Lib
 
 public func useTypesA(a: ExportedType) {}
@@ -162,7 +162,7 @@ public func useTypesD(a: ExportedType) {}
 
 //--- SwiftLibClient_FileA.swift
 /// Prefer the import matching public-module-name.
-public import SwiftPublicNameCore
+public import SwiftPublicNameCore // expected-warning {{public import of 'SwiftPublicNameCore' was not used in public declarations or inlinable code}}
 public import SwiftPublicName
 
 public func useTypesA(a: SwiftStruct) {}