tweak(syntax): hide posframe on next user input

Close: #7813
Ref: #6416
Co-authored-by: Dev380 <Dev380@users.noreply.github.com>

modules/checkers/syntax/README.org

@@ -25,6 +25,9 @@ This module provides syntax checking and error highlighting, powered by
 ** Hacks
 - If ~lsp-ui-mode~ is active, most of the aesthetic functionality of this module
   is turned off, as they show the same information.
+- If childframes are enabled, and the flycheck childframe is shown, it will be
+  hidden on the next user input (as well as the default behavior: to hide it the
+  next time the user is idle for ~flycheck-display-errors-delay~ seconds).
 
 ** TODO Changelog
 # This section will be machine generated. Don't edit it by hand.

modules/checkers/syntax/config.el

@@ -74,6 +74,21 @@
   (setq flycheck-posframe-warning-prefix "! "
         flycheck-posframe-info-prefix "··· "
         flycheck-posframe-error-prefix "X ")
+
+  ;; HACK: Hide the flycheck posframe immediately on the next keypress/user
+  ;;   action, otherwise it lingers until the next time the user is idle.
+  (defun +syntax--flycheck-posframe-hide-h ()
+    (unless (flycheck-posframe-check-position)
+      (posframe-hide flycheck-posframe-buffer))
+    (remove-hook 'post-command-hook #'+syntax--flycheck-posframe-hide-h))
+
+  (defadvice! +syntax-hide-posframe-on-next-command-a (fn &rest args)
+    :around #'flycheck-posframe-show-posframe
+    (letf! ((defun posframe-show (&rest args)
+              (add-hook 'post-command-hook #'+syntax--flycheck-posframe-hide-h)
+              (apply posframe-show args)))
+      (apply fn args)))
+
   (after! company
     ;; Don't display popups if company is open
     (add-hook 'flycheck-posframe-inhibit-functions #'company--active-p))