Move :tools fly{check,spell} to :checkers {syntax,spell}

These modules were renamed so we can later generalize their
implementations, such as adding flymake support to the syntax checker.

modules/checkers/syntax/config.el

@@ -0,0 +1,79 @@
+;;; checkers/syntax/config.el -*- lexical-binding: t; -*-
+
+;;
+;;; Flycheck
+
+(use-package! flycheck
+  :commands flycheck-list-errors flycheck-buffer
+  :after-call doom-switch-buffer-hook after-find-file
+  :config
+  (setq flycheck-emacs-lisp-load-path 'inherit)
+
+  ;; Check only when saving or opening files. Newline & idle checks are a mote
+  ;; excessive, especially when that can easily catch code in an incomplete
+  ;; state, so we removed them.
+  (setq flycheck-check-syntax-automatically '(save mode-enabled))
+
+  ;; Display errors a little quicker (default is 0.9s)
+  (setq flycheck-display-errors-delay 0.25)
+
+  ;; Don't commandeer input focus if the error message pops up (happens when
+  ;; tooltips and childframes are disabled).
+  (set-popup-rule! "^\\*Flycheck error messages\\*" :select nil)
+
+  (add-hook! 'doom-escape-hook :append
+    (defun +syntax-check-buffer-h ()
+      "Flycheck buffer on ESC in normal mode."
+      (when flycheck-mode
+        (ignore-errors (flycheck-buffer))
+        nil)))
+
+  (map! :map flycheck-error-list-mode-map
+        :n "C-n"    #'flycheck-error-list-next-error
+        :n "C-p"    #'flycheck-error-list-previous-error
+        :n "j"      #'flycheck-error-list-next-error
+        :n "k"      #'flycheck-error-list-previous-error
+        :n "RET"    #'flycheck-error-list-goto-error
+        :n [return] #'flycheck-error-list-goto-error)
+
+  (global-flycheck-mode +1))
+
+
+(use-package! flycheck-popup-tip
+  :commands flycheck-popup-tip-show-popup flycheck-popup-tip-delete-popup
+  :init (add-hook 'flycheck-mode-hook #'+syntax-init-popups-h)
+  :config
+  (setq flycheck-popup-tip-error-prefix "✕ ")
+  (after! evil
+    ;; Don't display popups while in insert or replace mode, as it can affect
+    ;; the cursor's position or cause disruptive input delays.
+    (add-hook! '(evil-insert-state-entry-hook evil-replace-state-entry-hook)
+               #'flycheck-popup-tip-delete-popup)
+    (defadvice! +syntax--disable-flycheck-popup-tip-maybe-a (&rest _)
+      :before-while #'flycheck-popup-tip-show-popup
+      (if evil-local-mode
+          (eq evil-state 'normal)
+        (not (bound-and-true-p company-backend))))))
+
+
+(use-package! flycheck-posframe
+  :when (featurep! +childframe)
+  :defer t
+  :init (add-hook 'flycheck-mode-hook #'+flycheck-init-popups-h)
+  :config
+  (setq flycheck-posframe-warning-prefix "⚠ "
+        flycheck-posframe-info-prefix "··· "
+        flycheck-posframe-error-prefix "✕ ")
+  (after! company
+    ;; Don't display popups if company is open
+    (add-hook 'flycheck-posframe-inhibit-functions #'company--active-p))
+  (after! evil
+    ;; Don't display popups while in insert or replace mode, as it can affect
+    ;; the cursor's position or cause disruptive input delays.
+    (add-hook! 'flycheck-posframe-inhibit-functions
+               #'evil-insert-state-p
+               #'evil-replace-state-p)))
+
+
+;;
+;;; TODO Flymake