[PATCH] clang-tools: Print information when clang-tidy tool is missing

[Maciej Falkowski]

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 patch adds more user-friendly information about missing tool by
checking the presence of clang-tidy using `command -v` at the beginning
of the script:

$ ./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@xxxxxxxxx>
Link: https://github.com/ClangBuiltLinux/linux/issues/1342
---
 scripts/clang-tools/run-clang-tools.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/scripts/clang-tools/run-clang-tools.py b/scripts/clang-tools/run-clang-tools.py
index fa7655c7cec0..d34eaf5a0ee5 100755
--- a/scripts/clang-tools/run-clang-tools.py
+++ b/scripts/clang-tools/run-clang-tools.py
@@ -60,6 +60,11 @@ def run_analysis(entry):
 
 
 def main():
+    exitcode = subprocess.getstatusoutput('command -v clang-tidy')[0]
+    if exitcode == 1:
+        print("Command 'clang-tidy' is missing in the system", file=sys.stderr)
+        sys.exit(127)
+
     args = parse_arguments()
 
     lock = multiprocessing.Lock()
-- 
2.26.3