Merge pull request #62166 from nkcsgexi/allowable-client-flag

Author: nkcsgexi

include/swift/Option/Options.td

@@ -1340,6 +1340,10 @@ def user_module_version : Separate<["-"], "user-module-version">,
   HelpText<"Module version specified from Swift module authors">,
   MetaVarName<"<vers>">;
 
+def allowable_client : Separate<["-"], "allowable-client">,
+  Flags<[FrontendOption, ModuleInterfaceOptionIgnorable, NewDriverOnlyOption]>,
+  HelpText<"Module names that are allowed to import this module">,
+  MetaVarName<"<vers>">;
 // VFS
 
 def vfsoverlay : JoinedOrSeparate<["-"], "vfsoverlay">,

test/ModuleInterface/allowable-client.swift

@@ -0,0 +1,10 @@
+// RUN: %empty-directory(%t)
+// RUN: %empty-directory(%t/textual)
+// RUN: %empty-directory(%t/binary)
+
+// RUN: %target-swift-frontend -emit-module %s -module-name Foo -swift-version 5 -disable-implicit-concurrency-module-import -allowable-client FooFriend1 -allowable-client FooFriend2 -allowable-client FooFriend3 -emit-module-interface-path %t/textual/Foo.swiftinterface -enable-library-evolution -emit-module-path %t/binary/Foo.swiftmodule
+
+// RUN: %FileCheck %s --check-prefix=INTERFACE-FLAG < %t/textual/Foo.swiftinterface
+
+// INTERFACE-FLAG: swift-module-flags-ignorable:
+// INTERFACE-FLAG: -allowable-client FooFriend1 -allowable-client FooFriend2 -allowable-client FooFriend3