[6.0][PackageCMO] Don't allow modifying AST

lib/SILOptimizer/IPO/CrossModuleOptimization.cpp

@@ -818,6 +818,21 @@ void CrossModuleOptimization::makeDeclUsableFromInline(ValueDecl *decl) {
   if (decl->getEffectiveAccess() >= AccessLevel::Package)
     return;
 
+  // FIXME: rdar://130456707
+  // Currently not all types are visited in canSerialize* calls, sometimes
+  // resulting in an internal type getting @usableFromInline, which is
+  // incorrect.
+  // For example, for `let q = P() as? Q`, where Q is an internal class
+  // inherting a public class P, Q is not visited in the canSerialize*
+  // checks, thus resulting in `@usableFromInline class Q`; this is not
+  // the intended behavior in the conservative mode as it modifies AST.
+  //
+  // To properly fix, instruction visitor needs to be refactored to do
+  // both the "canSerialize" check (that visits all types) and serialize
+  // or update visibility (modify AST in non-conservative modes). 
+  if (isPackageCMOEnabled(M.getSwiftModule()))
+    return;
+
   // We must not modify decls which are defined in other modules.
   if (M.getSwiftModule() != decl->getDeclContext()->getParentModule())
     return;

test/SILOptimizer/package-cmo-swiftinterface.swift

@@ -0,0 +1,66 @@
+// RUN: %empty-directory(%t)
+
+/// First Test: Check `@_usableFromInline` is not added to types in PackageCMO mode.
+// RUN: %target-swift-frontend -parse-as-library %s -O -wmo -enable-library-evolution -experimental-allow-non-resilient-access -experimental-package-cmo -module-name=Lib -package-name pkg -emit-module -o %t/Lib-package-cmo.swiftmodule
+// RUN: %target-sil-opt -module-name Lib -enable-sil-verify-all %t/Lib-package-cmo.swiftmodule -o %t/Lib-package-cmo.sil
+// RUN: %FileCheck %s < %t/Lib-package-cmo.sil
+
+/// Second Test: Check .swiftinterface files with and without PackageCMO have the same decl signatures without `@_usableFromInline`.
+// RUN: %target-swift-frontend -emit-module %s -I %t \
+// RUN:   -module-name Lib -package-name pkg \
+// RUN:   -enable-library-evolution -swift-version 6 \
+// RUN:   -emit-module-path %t/Lib.swiftmodule \
+// RUN:   -emit-module-interface-path %t/Lib.swiftinterface \
+// RUN:   -emit-private-module-interface-path %t/Lib.private.swiftinterface \
+// RUN:   -emit-package-module-interface-path %t/Lib.package.swiftinterface
+// RUN: %FileCheck %s --check-prefixes=CHECK-PKG-INTERFACE,CHECK-INTERFACE < %t/Lib.package.swiftinterface
+// RUN: %FileCheck %s --check-prefix=CHECK-INTERFACE < %t/Lib.swiftinterface
+
+// RUN: rm -rf %t/Lib.swiftmodule
+// RUN: rm -rf %t/Lib.swiftinterface
+// RUN: rm -rf %t/Lib.private.swiftinterface
+// RUN: rm -rf %t/Lib.package.swiftinterface
+
+// RUN: %target-swift-frontend -emit-module %s -I %t \
+// RUN:   -module-name Lib -package-name pkg \
+// RUN:   -enable-library-evolution -swift-version 6 \
+// RUN:   -O -wmo \
+// RUN:   -experimental-allow-non-resilient-access -experimental-package-cmo \
+// RUN:   -emit-module-path %t/Lib.swiftmodule \
+// RUN:   -emit-module-interface-path %t/Lib.swiftinterface \
+// RUN:   -emit-private-module-interface-path %t/Lib.private.swiftinterface \
+// RUN:   -emit-package-module-interface-path %t/Lib.package.swiftinterface
+// RUN: %FileCheck %s --check-prefixes=CHECK-PKG-INTERFACE,CHECK-INTERFACE < %t/Lib.package.swiftinterface
+// RUN: %FileCheck %s --check-prefix=CHECK-INTERFACE < %t/Lib.swiftinterface
+
+// REQUIRES: swift_in_compiler
+
+// CHECK-NOT: @usableFromInline
+final class InternalKlass: PkgKlass {
+    @inline(never)
+    override func bar() -> Int { return 13 }
+}
+
+package class PkgKlass {
+    @inline(never)
+    package func bar() -> Int { return 11 }
+}
+
+// CHECK-NOT: sil package [serialized_for_package] [noinline] [canonical] @$s3Lib3fooySiSgAA8PkgKlassCF : $@convention(thin) (@guaranteed PkgKlass) -> Optional<Int> {
+// CHECK-NOT: checked_cast_br PkgKlass in {{.*}} : $PkgKlass to InternalKlass
+@inline(never)
+package func foo(_ arg: PkgKlass) -> Int? {
+    let x = arg as? InternalKlass
+    return x?.bar()
+}
+
+public func run() -> Int {
+  return PkgKlass().bar()
+}
+
+// CHECK-PKG-INTERFACE-NOT: @usableFromInline
+// CHECK-INTERFACE-NOT: @usableFromInline
+// CHECK-PKG-INTERFACE: package class PkgKlass {
+// CHECK-PKG-INTERFACE:   @inline(never) package func bar() -> Swift.Int
+// CHECK-PKG-INTERFACE:   @inline(never) package func foo(_ arg: Lib.PkgKlass) -> Swift.Int?
+// CHECK-INTERFACE: public func run() -> Swift.Int