Add package-name flag to public .swiftinterface

Usually package symbols are not printed in public .swiftinterface
but if they are @usableFromInlinable or @inlinable they are printed.
However, the -package-name flag is not visible (currently only printed
in .private.swiftinterface); this was intended to ensure a strict
boundary between external clients and a package. This however causes
ABI breakage; it is possible for an external client to access a symbol
that used to be public but now @usableFromInlinable package.

This PR adds the flag back into the public interface as it was previously
written. The ignorable private flag flow is left as is, in case we might
have to move the flag back to that category. We will separately track adding
a guard around the package-name value for SDKs to make sure they are public
facing names.

Resolves rdar://116142791

Author: elsh

include/swift/Option/Options.td

@@ -542,7 +542,7 @@ def module_abi_name : Separate<["-"], "module-abi-name">,
   Flags<[FrontendOption, ModuleInterfaceOption]>,
   HelpText<"ABI name to use for the contents of this module">;
 def package_name : Separate<["-"], "package-name">,
-  Flags<[FrontendOption, ModuleInterfaceOptionIgnorablePrivate]>,
+  Flags<[FrontendOption, ModuleInterfaceOption]>,
   HelpText<"Name of the package the module belongs to">;
 def export_as : Separate<["-"], "export-as">,
   Flags<[FrontendOption, ModuleInterfaceOption]>,

test/Sema/accessibility_package_interface.swift

@@ -14,19 +14,22 @@
 // CHECK-PUBLIC-NOT: -package-name swift-utils.log
 // CHECK-PUBLIC-NOT: package func packageFunc()
 // CHECK-PUBLIC: -module-name Utils
+// CHECK-PUBLIC: -package-name swift-utils.log
 // CHECK-PUBLIC: public func publicFunc()
 
 // RUN: %target-swift-typecheck-module-from-interface(%t/Utils.private.swiftinterface) -module-name Utils -I %t
 // RUN: %FileCheck %s --check-prefix=CHECK-PRIVATE < %t/Utils.private.swiftinterface
 
+// CHECK-PRIVATE-NOT: swift-module-flags-ignorable-private: -package-name swift-utils.log
 // CHECK-PRIVATE-NOT: package func packageFunc()
-// CHECK-PRIVATE: swift-module-flags-ignorable-private: -package-name swift-utils.log
+// CHECK-PRIVATE: -package-name swift-utils.log
 // CHECK-PRIVATE: public func publicFunc()
 
 // RUN: %target-swift-frontend -typecheck %t/Client.swift -package-name swift-utils.log -I %t -verify
 
 //--- Utils.swift
 package func packageFunc() {}
+@usableFromInline package func ufiPackageFunc() {}
 public func publicFunc() {}
 
 //--- Client.swift
@@ -36,3 +39,7 @@ func clientFunc() {
   packageFunc()
   publicFunc()
 }
+
+@inlinable public func inlinableClientFunc() {
+    ufiPackageFunc()
+}

test/Serialization/load_package_module.swift

@@ -19,11 +19,12 @@
 // RUN: %target-swift-typecheck-module-from-interface(%t/LibInterface.swiftinterface) -I %t
 // RUN: %FileCheck %s --check-prefix=CHECK-PUBLIC < %t/LibInterface.swiftinterface
 // CHECK-PUBLIC: -module-name LibInterface
-// CHECK-PUBLIC-NOT: -package-name
+// CHECK-PUBLIC: -package-name libPkg
 
 // RUN: %target-swift-typecheck-module-from-interface(%t/LibInterface.private.swiftinterface) -module-name LibInterface -I %t
 // RUN: %FileCheck %s --check-prefix=CHECK-PRIVATE < %t/LibInterface.private.swiftinterface
-// CHECK-PRIVATE: swift-module-flags-ignorable-private: -package-name libPkg
+// CHECK-PRIVATE-NOT: swift-module-flags-ignorable-private: -package-name libPkg
+// CHECK-PRIVATE: -package-name libPkg
 
 // RUN: not %target-swift-frontend -typecheck %t/ClientLoadInterface.swift -package-name otherPkg -I %t 2> %t/resultX.output
 // RUN: %FileCheck %s -check-prefix CHECK-X < %t/resultX.output

test/Serialization/module_package_name.swift

@@ -11,12 +11,13 @@
 // RUN: %target-swift-typecheck-module-from-interface(%t/Logging.swiftinterface) -I %t
 // RUN: %FileCheck %s --check-prefix=CHECK-PUBLIC < %t/Logging.swiftinterface
 // CHECK-PUBLIC: -module-name Logging
-// CHECK-PUBLIC-NOT: -package-name
+// CHECK-PUBLIC: -package-name MyLoggingPkg
 
 // RUN: %target-swift-typecheck-module-from-interface(%t/Logging.private.swiftinterface) -module-name Logging -I %t
 // RUN: %FileCheck %s --check-prefix=CHECK-PRIVATE < %t/Logging.private.swiftinterface
+// CHECK-PRIVATE-NOT: swift-module-flags-ignorable-private: -package-name MyLoggingPkg
 // CHECK-PRIVATE: -module-name Logging
-// CHECK-PRIVATE: swift-module-flags-ignorable-private: -package-name MyLoggingPkg
+// CHECK-PRIVATE: -package-name MyLoggingPkg
 
 //--- File.swift
 public func log(level: Int) {}