[PATCH 1/2] Makefile: clang-tools: Print information when clang-tidy tool is missing

[Maciej Falkowski <maciej.falkowski9@gmail.com>]

When `clang-tidy` tool is missing in the system, the FileNotFoundError
exception is raised in the program reporting a stack trace to the user:

$ ./scripts/clang-tools/run-clang-tools.py clang-tidy ./compile_commands.json
multiprocessing.pool.RemoteTraceback:
"""
Traceback (most recent call last):
  File "/usr/lib64/python3.8/multiprocessing/pool.py", line 125, in worker
    result = (True, func(*args, **kwds))
  File "/usr/lib64/python3.8/multiprocessing/pool.py", line 48, in mapstar
    return list(map(*args))
  File "./scripts/clang-tools/run-clang-tools.py", line 54, in run_analysis
    p = subprocess.run(["clang-tidy", "-p", args.path, checks, entry["file"]],
  File "/usr/lib64/python3.8/subprocess.py", line 489, in run
    with Popen(*popenargs, **kwargs) as process:
  File "/usr/lib64/python3.8/subprocess.py", line 854, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/usr/lib64/python3.8/subprocess.py", line 1702, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: 'clang-tidy'
"""

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "./scripts/clang-tools/run-clang-tools.py", line 74, in <module>
    main()
  File "./scripts/clang-tools/run-clang-tools.py", line 70, in main
    pool.map(run_analysis, datastore)
  File "/usr/lib64/python3.8/multiprocessing/pool.py", line 364, in map
    return self._map_async(func, iterable, mapstar, chunksize).get()
  File "/usr/lib64/python3.8/multiprocessing/pool.py", line 771, in get
    raise self._value
FileNotFoundError: [Errno 2] No such file or directory: 'clang-tidy'

The patch adds more user-friendly information on the missing tool by
catching FileNotFoundError for `clang-tidy` file and raising exception
again for possible other files:

$ ./scripts/clang-tools/run-clang-tools.py clang-tidy ./compile_commands.json
Command `clang-tidy` is missing in the system.

Signed-off-by: Maciej Falkowski <maciej.falkowski9@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/1342
---
 scripts/clang-tools/run-clang-tools.py | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/scripts/clang-tools/run-clang-tools.py b/scripts/clang-tools/run-clang-tools.py
index fa7655c7cec0..38fc311d2e03 100755
--- a/scripts/clang-tools/run-clang-tools.py
+++ b/scripts/clang-tools/run-clang-tools.py
@@ -67,7 +67,13 @@ def main():
     # Read JSON data into the datastore variable
     with open(args.path, "r") as f:
         datastore = json.load(f)
-        pool.map(run_analysis, datastore)
+        try:
+            pool.map(run_analysis, datastore)
+        except FileNotFoundError as not_found:
+            if not_found.filename == 'clang-tidy':
+                print('Command `clang-tidy` is missing in the system.')
+            else:
+                raise not_found
 
 
 if __name__ == "__main__":
-- 
2.26.3