[llvm] [lit][bazel] Fall back to a default PATHEXT when the variable is unset (PR #217416)

[via llvm-commits]

https://github.com/UebelAndre updated https://github.com/llvm/llvm-project/pull/217416

>From 38dd4a3b832903de200f0cd52e9fa67cd51ec6c8 Mon Sep 17 00:00:00 2001
From: UebelAndre <github at uebelandre.com>
Date: Wed, 19 Aug 2026 11:00:14 -0700
Subject: [PATCH] [lit][bazel] Fall back to a default PATHEXT when the variable
 is unset

---
 llvm/utils/lit/lit/util.py | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/llvm/utils/lit/lit/util.py b/llvm/utils/lit/lit/util.py
index 8ab109fe15d45..5ca158f358cd8 100644
--- a/llvm/utils/lit/lit/util.py
+++ b/llvm/utils/lit/lit/util.py
@@ -11,6 +11,7 @@
 import sys
 import threading
 
+
 def pythonize_bool(value):
     if value is None:
         return False
@@ -43,10 +44,9 @@ def usable_core_count():
 
     return n
 
-def abs_path_preserve_drive(path):
-    """Return the absolute path without resolving drive mappings on Windows.
 
-    """
+def abs_path_preserve_drive(path):
+    """Return the absolute path without resolving drive mappings on Windows."""
     if platform.system() == "Windows":
         # Windows has limitations on path length (MAX_PATH) that
         # can be worked around using substitute drives, which map
@@ -131,6 +131,10 @@ def which(command, paths=None):
     # On Cygwin, 'PATHEXT' may exist but it should not be used.
     if os.pathsep == ";":
         pathext = os.environ.get("PATHEXT", "").split(";")
+        # If PATHEXT was stripped from the environment then use
+        # a sane fallback so binaries can still be located.
+        if not any(pathext):
+            pathext = [".COM", ".EXE", ".BAT", ".CMD"]
     else:
         pathext = [""]
 
@@ -333,7 +337,7 @@ def addAIXVersion(target_triple):
     """Add the AIX version to the given target triple,
     e.g. powerpc64-ibm-aix7.2.5.6
     """
-    os_cmd = "oslevel -s | awk -F\'-\' \'{printf \"%.1f.%d.%d\", $1/1000, $2, $3}\'"
+    os_cmd = "oslevel -s | awk -F'-' '{printf \"%.1f.%d.%d\", $1/1000, $2, $3}'"
     os_version = subprocess.run(os_cmd, capture_output=True, shell=True).stdout.decode()
     return re.sub("aix", "aix" + os_version, target_triple)