Switch to using a proper quote function

Don't use shlex.quote(), that's documented to only be relevant
for Unix (and it uses single quotes which aren't normally
tolerated by windows shells - even if the lit internal shell
does handle them). Additionally, shlex.quote() always quotes
paths that include backslashes, even if those don't need quoting
on Windows.

Author: mstorsjo

libcxx/utils/libcxx/test/params.py

@@ -7,12 +7,17 @@
 # ===----------------------------------------------------------------------===##
 import sys
 import re
+import subprocess
 from pathlib import Path
 
 from libcxx.test.dsl import *
 from libcxx.test.features import _isMSVC
 
 
+def quote(x):
+    return subprocess.list2cmdline([x])
+
+
 _warningFlags = [
     "-Werror",
     "-Wall",
@@ -320,7 +325,7 @@ def getStdFlag(cfg, std):
     Parameter(
         name="executor",
         type=str,
-        default=f"\"{sys.executable}\" {Path(__file__).resolve().parent.parent.parent / 'run.py'}",
+        default=f"{quote(sys.executable)} {quote(str(Path(__file__).resolve().parent.parent.parent / 'run.py'))}",
         help="Custom executor to use instead of the configured default.",
         actions=lambda executor: [AddSubstitution("%{executor}", executor)],
     )