Option to disable printing package-name in public or private interface.

Having package-name flag in non-package interfaces causes them to be built as if
belonging to a package, which causes an issue for a loading client outside of the
package as follows.

For example, when building X that depends on A with the following dependency chain:
  X --> A --> B --(package-only)--> C

1. X itself is not in the same package as A, B, and C.
2. When dependency scanning X, and opening up B, because the scan target is in a
   different package domain, the scanner decides that B's package-only dependency
   on C is to be ignored.
3. When then finally building A itself, it will load its dependencies, but because
   the .private.swiftinterface of A still specifies -package-name, when it loads
   B, it will then examine its dependencies and deem that this package-only dependency
   on C is required.

Because (2) and (3) disagree, we get an error now when building the private A textual interface.

rdar://130701866

Author: elsh

include/swift/Frontend/ModuleInterfaceSupport.h

@@ -62,6 +62,10 @@ struct ModuleInterfaceOptions {
   /// Print imports that are missing from the source and used in API.
   bool PrintMissingImports = true;
 
+  /// If true, package-name flag is not printed in either public or private
+  /// interface file.
+  bool DisablePackageNameForNonPackageInterface = false;
+
   /// Intentionally print invalid syntax into the file.
   bool DebugPrintInvalidSyntax = false;
 

include/swift/Option/Options.td

@@ -717,6 +717,11 @@ def disable_bridging_pch : Flag<["-"], "disable-bridging-pch">,
   Flags<[HelpHidden]>,
   HelpText<"Disable automatic generation of bridging PCH files">;
 
+def disable_print_package_name_for_non_package_interface :
+  Flag<["-"], "disable-print-package-name-for-non-package-interface">,
+  Flags<[FrontendOption, NoDriverOption, ModuleInterfaceOption, HelpHidden]>,
+  HelpText<"Disable adding package name to public or private interface">;
+
 def lto : Joined<["-"], "lto=">,
   Flags<[FrontendOption, NoInteractiveOption]>,
   HelpText<"Specify the LTO type to either 'llvm-thin' or 'llvm-full'">;

lib/Frontend/CompilerInvocation.cpp

@@ -419,6 +419,7 @@ static void ParseModuleInterfaceArgs(ModuleInterfaceOptions &Opts,
     Args.hasArg(OPT_debug_emit_invalid_swiftinterface_syntax);
   Opts.PrintMissingImports =
     !Args.hasArg(OPT_disable_print_missing_imports_in_module_interface);
+  Opts.DisablePackageNameForNonPackageInterface |= Args.hasArg(OPT_disable_print_package_name_for_non_package_interface);
 
   if (const Arg *A = Args.getLastArg(OPT_library_level)) {
     StringRef contents = A->getValue();

lib/Frontend/ModuleInterfaceSupport.cpp

@@ -59,8 +59,35 @@ static void printToolVersionAndFlagsComment(raw_ostream &out,
       << InterfaceFormatVersion << "\n";
   out << "// " SWIFT_COMPILER_VERSION_KEY ": "
       << ToolsVersion << "\n";
+
+  // Check if printing package-name is disabled for
+  // non-package interfaces (by default, it's printed
+  // in all interfaces).
+  std::string flagsStr = Opts.Flags;
+  if (Opts.DisablePackageNameForNonPackageInterface &&
+      !Opts.printPackageInterface()) {
+    size_t pkgIdx = 0;
+    size_t end = flagsStr.size();
+    auto pkgFlag = StringRef("-package-name ");
+    size_t pkgLen = pkgFlag.size();
+
+    // Find the package-name flag and its value and
+    // drop them. There can be multiple package-name
+    // flags passed, so drop them all.
+    while (pkgIdx < end) {
+      // First, find "-package-name "
+      pkgIdx = flagsStr.find(pkgFlag, 0);
+      if (pkgIdx == std::string::npos)
+        break;
+      // If found, find the next flag's starting pos.
+      auto next = flagsStr.find_first_of("-", pkgIdx + pkgLen + 1);
+      // Remove the substr in-place.
+      flagsStr.erase(pkgIdx, next - pkgIdx);
+    }
+  }
+
   out << "// " SWIFT_MODULE_FLAGS_KEY ": "
-      << Opts.Flags;
+      << flagsStr;
 
   // Insert additional -module-alias flags
   if (Opts.AliasModuleNames) {

lib/Sema/TypeCheckAttr.cpp

@@ -1058,6 +1058,12 @@ bool AttributeChecker::visitAbstractAccessControlAttr(
       D->getASTContext().LangOpts.PackageName.empty() &&
       File && File->Kind != SourceFileKind::Interface) {
     // `package` modifier used outside of a package.
+    // Error if a source file contains a package decl or `package import` but
+    // no package-name is passed.
+    // Note that if the file containing the package decl is a public (or private)
+    // interface file, the decl must be @usableFromInline (or "inlinable"),
+    // effectively getting "public" visibility; in such case, package-name is
+    // not needed, and typecheck on those decls are skipped.
     diagnose(attr->getLocation(), diag::access_control_requires_package_name,
              isa<ValueDecl>(D), D);
     return true;

test/ModuleInterface/package_interface_disable_package_name.swift

@@ -0,0 +1,62 @@
+// RUN: %empty-directory(%t)
+
+/// Do not print package-name for public or private interfaces
+// RUN: %target-build-swift -emit-module %s -I %t \
+// RUN:   -module-name Bar -package-name foopkg \
+// RUN:   -enable-library-evolution -swift-version 6 \
+// RUN:   -package-name barpkg \
+// RUN:   -Xfrontend -disable-print-package-name-for-non-package-interface \
+// RUN:   -emit-module-interface-path %t/Bar.swiftinterface \
+// RUN:   -emit-private-module-interface-path %t/Bar.private.swiftinterface \
+// RUN:   -emit-package-module-interface-path %t/Bar.package.swiftinterface
+
+// RUN: %FileCheck %s --check-prefix=CHECK-PUBLIC < %t/Bar.swiftinterface
+// RUN: %FileCheck %s --check-prefix=CHECK-PRIVATE < %t/Bar.private.swiftinterface
+// RUN: %FileCheck %s --check-prefix=CHECK-PACKAGE < %t/Bar.package.swiftinterface
+
+// CHECK-PUBLIC-NOT: -package-name foopkg
+// CHECK-PUBLIC-NOT: -package-name barpkg
+// CHECK-PRIVATE-NOT: -package-name foopkg
+// CHECK-PRIVATE-NOT: -package-name barpkg
+// CHECK-PACKAGE-NOT: -package-name foopkg
+// CHECK-PACKAGE: -package-name barpkg
+
+// CHECK-PUBLIC: -module-name Bar
+// CHECK-PRIVATE: -module-name Bar
+// CHECK-PACKAGE: -module-name Bar
+
+// RUN: %target-swift-frontend -compile-module-from-interface %t/Bar.swiftinterface -o %t/Bar.swiftmodule -module-name Bar
+// RUN: rm -rf %t/Bar.swiftmodule
+// RUN: %target-swift-frontend -compile-module-from-interface %t/Bar.private.swiftinterface -o %t/Bar.swiftmodule -module-name Bar
+// RUN: rm -rf %t/Bar.swiftmodule
+// RUN: %target-swift-frontend -compile-module-from-interface %t/Bar.package.swiftinterface -o %t/Bar.swiftmodule -module-name Bar
+
+// RUN: rm -rf %t/Bar.swiftmodule
+// RUN: rm -rf %t/Bar.swiftinterface
+// RUN: rm -rf %t/Bar.private.swiftinterface
+// RUN: rm -rf %t/Bar.package.swiftinterface
+
+/// By default, -package-name is printed in all interfaces.
+// RUN: %target-build-swift -emit-module %s -I %t \
+// RUN:   -module-name Bar -package-name barpkg \
+// RUN:   -enable-library-evolution -swift-version 6 \
+// RUN:   -emit-module-interface-path %t/Bar.swiftinterface \
+// RUN:   -emit-private-module-interface-path %t/Bar.private.swiftinterface \
+// RUN:   -emit-package-module-interface-path %t/Bar.package.swiftinterface
+
+// RUN: %FileCheck %s < %t/Bar.swiftinterface
+// RUN: %FileCheck %s < %t/Bar.private.swiftinterface
+// RUN: %FileCheck %s < %t/Bar.package.swiftinterface
+
+// CHECK: -package-name barpkg
+// CHECK: -module-name Bar
+
+// RUN: %target-swift-frontend -compile-module-from-interface %t/Bar.swiftinterface -o %t/Bar.swiftmodule -module-name Bar
+// RUN: rm -rf %t/Bar.swiftmodule
+// RUN: %target-swift-frontend -compile-module-from-interface %t/Bar.private.swiftinterface -o %t/Bar.swiftmodule -module-name Bar
+// RUN: rm -rf %t/Bar.swiftmodule
+// RUN: %target-swift-frontend -compile-module-from-interface %t/Bar.package.swiftinterface -o %t/Bar.swiftmodule -module-name Bar
+
+public struct PubStruct {}
+@_spi(bar) public struct SPIStruct {}
+package struct PkgStruct {}