[PackageSyntax] Run the bootstrap script without PackageSyntax if Swi…

…ftSyntax isn't checked out or --skip-package-syntax is passed

Utilities/bootstrap

@@ -23,7 +23,7 @@ import platform
 import re
 import shutil
 import subprocess
-from helpers import note, error, symlink_force, mkdir_p, call, call_output
+from helpers import note, warning, error, symlink_force, mkdir_p, call, call_output
 
 g_macos_deployment_target = '10.15'
 
@@ -144,6 +144,10 @@ def add_build_args(parser):
         dest="cross_compile_hosts",
         help="List of cross compile hosts targets.",
         default=[])
+    parser.add_argument(
+        "--skip-package-syntax",
+        action="store_true",
+        help="Build the second stage without PackageSyntax support.")
 
 def add_test_args(parser):
     """Configures the parser with the arguments necessary for the test action."""
@@ -173,6 +177,7 @@ def parse_global_args(args):
     args.swift_argument_parser_source_dir = os.path.join(args.project_root, "..", "swift-argument-parser")
     args.swift_driver_source_dir = os.path.join(args.project_root, "..", "swift-driver")
     args.swift_crypto_source_dir = os.path.join(args.project_root, "..", "swift-crypto")
+    args.swift_syntax_source_dir = os.path.join(args.project_root, "..", "swift-syntax")
     args.source_root = os.path.join(args.project_root, "Sources")
 
     if platform.system() == 'Darwin':
@@ -723,7 +728,13 @@ def get_swiftpm_env_cmd(args):
     if args.llbuild_link_framework:
         env_cmd.append("SWIFTPM_LLBUILD_FWK=1")
     env_cmd.append("SWIFTCI_USE_LOCAL_DEPS=1")
-    env_cmd.append("SPM_BUILD_PACKAGE_SYNTAX=1")
+
+    # Build package editor support if swift-syntax is checked out.
+    if os.path.exists(args.swift_syntax_source_dir) and not args.skip_package_syntax:
+        env_cmd.append("SPM_BUILD_PACKAGE_SYNTAX=1")
+    elif not args.skip_package_syntax:
+        warning("Skipping build of PackageSyntax because no SwiftSyntax checkout was found")
+
     env_cmd.append("SWIFTPM_MACOS_DEPLOYMENT_TARGET=%s" % g_macos_deployment_target)
 
     if args.bootstrap:

Utilities/helpers.py

@@ -19,6 +19,10 @@ def note(message):
     print("--- %s: note: %s" % (os.path.basename(sys.argv[0]), message))
     sys.stdout.flush()
 
+def warning(message):
+    print("--- %s: warning: %s" % (os.path.basename(sys.argv[0]), message))
+    sys.stdout.flush()
+
 def error(message):
     print("--- %s: error: %s" % (os.path.basename(sys.argv[0]), message))
     sys.stdout.flush()