[LIT] replace lit.util.mkdir with pathlib.Path.mkdir (#163948)

`lit.util.mkdir` and `lit.util.mkdir_p` were written during the Python
2.x era.
Since modern `pathlib` functions have similar functionality, we can
simply use those instead.

If you encounter a path length issue after this change, the registry
value `LongPathsEnabled` must be set as described in
https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation
. Note that the Python runtime is already marked as a `longPathAware`
executable.

**Background:**

On Cygwin, a file named `file_name.exe` can be accessed without the
suffix, simply as `file_name`, as shown below:

```
$ echo > file_name.exe

$ file file_name.exe
file_name.exe: very short file (no magic)

$ file file_name
file_name: very short file (no magic)
```

In this situation, while running `mkdir file_name` works as intended,
checking for the existence of the target before calling `mkdir`
incorrectly reports that it already exists and thus skips the directory
creation.

```
$ test -e file_name && echo exists
exists

$ mkdir file_name && echo ok
ok

$ file file_name
file_name: directory
```

Therefore, the existence pre-check should be skipped on Cygwin. Instead
of add a workaround, refactored them.

Author: kikairoya

llvm/utils/lit/lit/TestRunner.py

@@ -462,16 +462,15 @@ def executeBuiltinMkdir(cmd, cmd_shenv):
     stderr = StringIO()
     exitCode = 0
     for dir in args:
-        cwd = cmd_shenv.cwd
-        dir = to_unicode(dir) if kIsWindows else to_bytes(dir)
-        cwd = to_unicode(cwd) if kIsWindows else to_bytes(cwd)
-        if not os.path.isabs(dir):
-            dir = lit.util.abs_path_preserve_drive(os.path.join(cwd, dir))
+        dir = pathlib.Path(dir)
+        cwd = pathlib.Path(to_unicode(cmd_shenv.cwd))
+        if not dir.is_absolute():
+            dir = lit.util.abs_path_preserve_drive(cwd / dir)
         if parent:
-            lit.util.mkdir_p(dir)
+            dir.mkdir(parents=True, exist_ok=True)
         else:
             try:
-                lit.util.mkdir(dir)
+                dir.mkdir(exist_ok=True)
             except OSError as err:
                 stderr.write("Error: 'mkdir' command failed, %s\n" % str(err))
                 exitCode = 1
@@ -2411,7 +2410,7 @@ def runOnce(
         return out, err, exitCode, timeoutInfo, status
 
     # Create the output directory if it does not already exist.
-    lit.util.mkdir_p(os.path.dirname(tmpBase))
+    pathlib.Path(tmpBase).parent.mkdir(parents=True, exist_ok=True)
 
     # Re-run failed tests up to test.allowed_retries times.
     execdir = os.path.dirname(test.getExecPath())

llvm/utils/lit/lit/util.py

@@ -5,6 +5,7 @@
 import math
 import numbers
 import os
+import pathlib
 import platform
 import re
 import signal
@@ -131,48 +132,17 @@ def abs_path_preserve_drive(path):
         # Since Python 3.8, os.path.realpath resolves sustitute drives,
         # so we should not use it. In Python 3.7, os.path.realpath
         # was implemented as os.path.abspath.
+        if isinstance(path, pathlib.Path):
+            return path.absolute()
         return os.path.abspath(path)
     else:
         # On UNIX, the current directory always has symbolic links resolved,
         # so any program accepting relative paths cannot preserve symbolic
         # links in paths and we should always use os.path.realpath.
+        if isinstance(path, pathlib.Path):
+            return path.resolve()
         return os.path.realpath(path)
 
-def mkdir(path):
-    try:
-        if platform.system() == "Windows":
-            from ctypes import windll
-            from ctypes import GetLastError, WinError
-
-            path = os.path.abspath(path)
-            # Make sure that the path uses backslashes here, in case
-            # python would have happened to use forward slashes, as the
-            # NT path format only supports backslashes.
-            path = path.replace("/", "\\")
-            NTPath = to_unicode(r"\\?\%s" % path)
-            if not windll.kernel32.CreateDirectoryW(NTPath, None):
-                raise WinError(GetLastError())
-        else:
-            os.mkdir(path)
-    except OSError:
-        e = sys.exc_info()[1]
-        # ignore EEXIST, which may occur during a race condition
-        if e.errno != errno.EEXIST:
-            raise
-
-
-def mkdir_p(path):
-    """mkdir_p(path) - Make the "path" directory, if it does not exist; this
-    will also make directories for any missing parent directories."""
-    if not path or os.path.exists(path):
-        return
-
-    parent = os.path.dirname(path)
-    if parent != path:
-        mkdir_p(parent)
-
-    mkdir(path)
-
 
 def listdir_files(dirname, suffixes=None, exclude_filenames=None, prefixes=None):
     """Yields files in a directory.

llvm/utils/lit/tests/Inputs/shtest-glob/example_dir1.input/empty

@@ -1,2 +1,7 @@
 ## Tests glob pattern handling in the mkdir command.
+
+## This mkdir should fail because the `example_file*.input`s are regular files.
 # RUN: not mkdir %S/example_file*.input
+
+## This mkdir should succeed (so RUN should fail) because the `example_dir*.input`s that already exist are directories.
+# RUN: not mkdir %S/example_dir*.input

llvm/utils/lit/tests/Inputs/shtest-glob/example_dir2.input/empty

@@ -1,12 +1,13 @@
 ## Tests glob pattern handling in echo command.
 
 # RUN: not %{lit} -a -v %{inputs}/shtest-glob \
-# RUN: | FileCheck -dump-input=fail -match-full-lines %s
-#
+# RUN: | FileCheck -dump-input=fail -match-full-lines --implicit-check-not=Error: %s
 # END.
 
 # CHECK: UNRESOLVED: shtest-glob :: glob-echo.txt ({{[^)]*}})
 # CHECK: TypeError: string argument expected, got 'GlobItem'
 
-# CHECK: FAIL: shtest-glob :: glob-mkdir.txt ({{[^)]*}})
-# CHECK: # error: command failed with exit status: 1
+# CHECK:      FAIL: shtest-glob :: glob-mkdir.txt ({{[^)]*}})
+# CHECK:      # | Error: 'mkdir' command failed, {{.*}}example_file1.input'
+# CHECK-NEXT: # | Error: 'mkdir' command failed, {{.*}}example_file2.input'
+# CHECK:      # error: command failed with exit status: 1