Version 1.3.7 of package Flymake has just been released in GNU ELPA. You can now find it in M-x list-packages RET.
Flymake describes itself as: ===================================== A universal on-the-fly syntax checker ===================================== More at https://elpa.gnu.org/packages/flymake.html ## Summary: Flymake is a minor Emacs mode performing on-the-fly syntax checks. Flymake collects diagnostic information for multiple sources, called backends, and visually annotates the relevant portions in the buffer. This file contains the UI for displaying and interacting with the results produced by these backends, as well as entry points for backends to hook on to. The main interactive entry point is the `flymake-mode' minor mode, which periodically and automatically initiates checks as the user is editing the buffer. The variables `flymake-no-changes-timeout', `flymake-start-on-flymake-mode' give finer control over the events triggering a check, as does the interactive command `flymake-start', which immediately starts a check. ## Recent NEWS: [Not available 🙁]