Add --print-build-dir option to build-script

If passed, build-script doesn’t build anything; it just prints the full path to the directory the invocation would have built its products in. This is intended to allow you to build tools which take build-script options like --debug and --xcode and use them to determine the build directory you’re currently using.

Author: beccadax

utils/build-script

@@ -1092,6 +1092,11 @@ def main_preset():
     parser.add_argument(
         "--build-dir",
         help="specify the directory where build artifact should be stored")
+    parser.add_argument(
+        "--print-build-dir",
+        help="Print the build directory and exit without building",
+        action="store_true",
+        default=False)
     args = parser.parse_args()
     if len(args.preset_file_names) == 0:
         args.preset_file_names = [
@@ -1141,6 +1146,8 @@ def main_preset():
     build_script_args = [sys.argv[0]]
     if args.dry_run:
         build_script_args += ["--dry-run"]
+    if args.print_build_dir:
+        build_script_args += ["--print-build-dir"]
 
     build_script_args += preset_args
     if args.distcc:
@@ -1226,6 +1233,10 @@ def main_normal():
     if args.show_sdks:
         debug.print_xcodebuild_versions()
 
+    if args.print_build_dir:
+        print(invocation.workspace.build_root)
+        return 0
+
     # Clean build directory if requested.
     if args.clean:
         clean_delay()

utils/build_swift/driver_arguments.py

@@ -333,6 +333,8 @@ def create_argument_parser():
            metavar='PATH',
            help='name of the directory under $SWIFT_BUILD_ROOT where the '
                 'build products will be placed')
+    option('--print-build-dir', toggle_true,
+           help='print the build directory and exit without building')
     option('--install-prefix', store_path,
            default=targets.install_prefix(),
            help='The installation prefix. This is where built Swift products '

utils/build_swift/tests/expected_options.py

@@ -161,6 +161,7 @@
     'tsan_libdispatch_test': False,
     'long_test': False,
     'lto_type': None,
+    'print_build_dir': False,
     'show_sdks': False,
     'skip_build': False,
     'stdlib_deployment_targets': None,
@@ -402,6 +403,7 @@ class IgnoreOption(_BaseOption):
     SetTrueOption('--benchmark'),
     SetTrueOption('--clean'),
     SetTrueOption('--dry-run'),
+    SetTrueOption('--print-build-dir'),
     SetTrueOption('--disable-guaranteed-normal-arguments'),
     SetTrueOption('--enable-stdlibcore-exclusivity-checking'),
     SetTrueOption('--force-optimized-typechecker'),