Bootstrap script needs to build PackageDescription (both 4 and 4_2) and PackagePlugin libraries universal when cross-compiling.

rdar://75186958

Author: abertelrud

Package.swift

@@ -121,7 +121,7 @@ let package = Package(
             /** Package Definition API */
             name: "PackageDescription",
             swiftSettings: [
-                .define("PACKAGE_DESCRIPTION_4_2"),
+                .define("PACKAGE_DESCRIPTION_\(ProcessInfo.processInfo.environment["SWIFTPM_PACKAGE_DESCRIPTION_VERSION"] ?? "4_2")"),
             ]),
 
         .target(

Utilities/bootstrap

@@ -202,6 +202,7 @@ def parse_build_args(args):
         args.target_dir = os.path.join(args.build_dir, get_build_target(args))
     args.bootstrap_dir = os.path.join(args.target_dir, "bootstrap")
     args.conf = 'release' if args.release else 'debug'
+    args.pkgdesc_version = "4_2"
     args.bin_dir = os.path.join(args.target_dir, args.conf)
     args.bootstrap = not args.skip_cmake_bootstrap or \
                      not os.path.exists(os.path.join(os.path.split(args.swiftc_path)[0], "swift-build"))
@@ -389,42 +390,16 @@ def install_swiftpm(prefix, args):
         dest = os.path.join(prefix, "libexec", "swift", "pm")
         install_binary(args, "swiftpm-xctest-helper", dest)
 
-    # Install PackageDescription runtime libraries.
-    runtime_lib_dest = os.path.join(prefix, "lib", "swift", "pm")
-    runtime_lib_src = os.path.join(args.bootstrap_dir, "pm")
-
-    for runtime in ["4", "4_2"]:
-        files_to_install = ["libPackageDescription" + g_shared_lib_ext]
-        if platform.system() == 'Darwin':
-            files_to_install.append("PackageDescription.swiftinterface")
-        else:
-            files_to_install.append("PackageDescription.swiftmodule")
-        files_to_install.append("PackageDescription.swiftdoc")
-
-        for file in files_to_install:
-            src = os.path.join(runtime_lib_src, runtime, file)
-            dest = os.path.join(runtime_lib_dest, runtime, file)
-            mkdir_p(os.path.dirname(dest))
-
-            note("Installing %s to %s" % (src, dest))
-
-            file_util.copy_file(src, dest, update=1)
-
-    files_to_install = ["libPackagePlugin" + g_shared_lib_ext]
-    if platform.system() == 'Darwin':
-        files_to_install.append("PackagePlugin.swiftinterface")
-    else:
-        files_to_install.append("PackagePlugin.swiftmodule")
-    files_to_install.append("PackagePlugin.swiftdoc")
-
-    for file in files_to_install:
-        src = os.path.join(runtime_lib_src, file)
-        dest = os.path.join(runtime_lib_dest, file)
-        mkdir_p(os.path.dirname(dest))
-
-        note("Installing %s to %s" % (src, dest))
-
-        file_util.copy_file(src, dest, update=1)
+    # Install the current variant of PackageDescription.
+    install_dylib(args, "PackageDescription", os.path.join(prefix, "lib", "swift", "pm", "4_2"), ["PackageDescription"])
+    
+    # Install the legacy variant of PackageDescription.
+    args_pd4 = args
+    args_pd4.build_dir = os.path.join(args.build_dir, "PD4")
+    install_dylib(args_pd4, "PackageDescription", os.path.join(prefix, "lib", "swift", "pm", "4"), ["PackageDescription"])
+    
+    # Install PackagePlugin.
+    install_dylib(args, "PackagePlugin", os.path.join(prefix, "lib", "swift", "pm"), ["PackagePlugin"])
 
 
 def install_libswiftpm_dylib(args, library_name, install_dir, module_names):
@@ -443,6 +418,18 @@ def install_libswiftpm_dylib(args, library_name, install_dir, module_names):
     dir_util.copy_tree(tscclibc_include_dir, tscclibc_include_dir_dest)
 
 
+def install_dylib(args, library_name, install_dir, module_names):
+    # Install the dynamic library itself.
+    # FIXME: Don't hardcode the library prefix.
+    install_binary(args, "lib" + library_name + g_shared_lib_ext, install_dir)
+
+    # Install the swiftmodule/swiftinterface and swiftdoc files for all the modules.
+    for module in module_names:
+        install_binary(args, module + ".swiftmodule", install_dir)
+        if not args.cross_compile_hosts: # When compiling for multiple arches, swiftdoc is part of the swiftmodule directory
+            install_binary(args, module + ".swiftdoc", install_dir)
+
+
 def install_binary(args, binary, dest_dir):
     src = os.path.join(args.bin_dir, binary)
     dest = os.path.join(dest_dir, binary)
@@ -647,8 +634,18 @@ def build_swiftpm_with_swiftpm(args, integrated_swift_driver):
 
     if integrated_swift_driver:
         swiftpm_args.append("--use-integrated-swift-driver")
-
+    
+    # Build SwiftPM, including libSwiftPM, all the command line tools, and the current variant of PackageDescription.
     call_swiftpm(args, swiftpm_args)
+    
+    # Also build the legacy variant of PackageDescription into a subdirectory of the build directory.
+    args_pd4 = args
+    args_pd4.build_dir = os.path.join(args.build_dir, "PD4")
+    args_pd4.pkgdesc_version = "4"
+    swiftpm_args_pd4 = swiftpm_args
+    swiftpm_args_pd4.append("--product")
+    swiftpm_args_pd4.append("PackageDescription")
+    call_swiftpm(args_pd4, swiftpm_args_pd4)
 
     # Setup symlinks that'll allow using swiftpm from the build directory.
     symlink_force(args.swiftc_path, os.path.join(args.target_dir, args.conf, "swiftc"))
@@ -713,6 +710,7 @@ def get_swiftpm_env_cmd(args):
         env_cmd.append("SWIFTPM_LLBUILD_FWK=1")
     env_cmd.append("SWIFTCI_USE_LOCAL_DEPS=1")
     env_cmd.append("SWIFTPM_MACOS_DEPLOYMENT_TARGET=%s" % g_macos_deployment_target)
+    env_cmd.append("SWIFTPM_PACKAGE_DESCRIPTION_VERSION=%s" % args.pkgdesc_version)
 
     if args.bootstrap:
         libs_joined = ":".join([