run-clang-tidy: Fix infinite loop on windows

[Febbe]

Summary

find_compilation_database checked only for "/" as exit point, but on Windows, this root is impossible.
Fixes #53642

[Febbe]

Currently, only tested on Windows.
This should also increase performance, since the path is canonicalized only once.

[Febbe]

I don't think I have commit rights, so someone of you also have to commit this.

[salman-javed-nz]

Just a drive-by comment to say, thank you for taking the time to make this fix. It's a bug I've triggered many times. Great to see it being resolved.

[JonasToth]

LGTM with a small nit.

i could commit on your behalf and check it for linux, too. But the change seems sane to me.

clang-tools-extra/clang-tidy/tool/run-clang-tidy.py

78–79

please delete the whitespace at the end of the line

[Febbe]

Applied the feedback

[Febbe]

@JonasToth yes, it would be nice, to test this and then push it for me. Also a backport to 14.0 would be good :).

[Febbe]

@salman-javed-nz you're welcome, I only fixed it because I saw the bug in the trace directly. Normally, I would only fix C/C++ stuff :D.

[JonasToth]

Sorry for the long delay, i simply forgot.
The patch is commited! :)

clang-tools-extra/clang-tidy/tool/run-clang-tidy.py

def strtobool(val):
   # Return ArgumentTypeError so that argparse does not substitute its own error message
   raise argparse.ArgumentTypeError(
     "'{}' is invalid value for boolean argument! Try 0 or 1.".format(val)
   )
 
 
 def find_compilation_database(path):
   """Adjusts the directory until a compilation database is found."""
-  result = './'
+  result = os.path.realpath('./')
   while not os.path.isfile(os.path.join(result, path)):
-    if os.path.realpath(result) == '/':
+    parent = os.path.dirname(result)
+    if result == parent:
       print('Error: could not find compilation database.')
       sys.exit(1)
-    result += '../'
-  return os.path.realpath(result)
+    result = parent
+  return result
 
 
 def make_absolute(f, directory):
   if os.path.isabs(f):
     return f
   return os.path.normpath(os.path.join(directory, f))