`tidy-checks=-*` triggers false-positive

[2bndy5]

I added this action to a project I'm helping. The project's owner is still learning C++, so I thought this action would help lament best practices...

I tried to disable clang-tidy by specifying

          tidy-checks: '-*'

but clang-tidy threw some errors which triggered an empty comment.

The workflow log reveals that clang-tidy didn't like being told to do nothing. The output from clang-tidy (which in this case was the --help output) was interpreted as though the user should be notified.

Error: no checks enabled.

I'd like to add a check in the run.py (run_clang_tidy()) that allows skipping clang-tidy when all checks are disabled (when tidy-checks=-*).

[2bndy5]

When debugging this locally, I found that main() still tries to read the events_payload.json file (only exists on the github runner) even though it doesn't need to when --files-changed-only=false. So, I'll throw in a fix for that as well.

I'm also going to remove the testing info I had hardcoded to the env var defaults.

[2bndy5]

I just found that only hidden directories (starting with .) at repo root are ignored. Meaning a hidden sub-directory would not be ignored. I'm fixing that while I'm debugging.

Also, I'm revising the get_line_cnt_from_cols() to open files as binary instead of encoded text. This should better support CRLF & LF line endings. The current implementation might lead to an infinite loop.

[2bndy5]

I found another error when the output from clang-format contains no fixes. Basically, the XML metadata is triggering a "Run clang-format" comment. This is an easy fix as the XML data is already being parsed to get line numbers of format suggestions.

[2bndy5]

encountered another bug when parsing clang-tidy notifications that contain std::<obj> in the notification explanation. Using better regexp matching to solve this.