feat(emacs-lisp): add reduced-flymake-byte-compile

This is a flymake backend that gives a reduced set of byte compiler
warnings in accordance too `+emacs-lisp-linter-warnings`

modules/lang/emacs-lisp/autoload.el

@@ -277,9 +277,71 @@ https://emacs.stackexchange.com/questions/10230/how-to-indent-keywords-aligned"
                                  file-base)))))))
          (not (locate-dominating-file default-directory ".doommodule")))))
 
+(defvar-local +emacs-lisp-reduced-flymake-byte-compile--process nil)
+
+(defun +emacs-lisp-reduced-flymake-byte-compile (report-fn &rest _args)
+  "A Flymake backend for warnings from the elisp byte compiler
+
+This checker reduces the amount of false positives the byte compiler throws off
+compared too `elisp-flymake-byte-compile'. The linter warnings that are enabled
+are set by `+emacs-lisp-linter-warnings'
+
+This backend does not need to be added directly
+as `+emacs-lisp-non-package-mode' will enable it and disable the other checkers."
+  ;; if a process already exists. kill it.
+  (when (and +emacs-lisp-reduced-flymake-byte-compile--process
+             (process-live-p +emacs-lisp-reduced-flymake-byte-compile--process))
+    (kill-process +emacs-lisp-reduced-flymake-byte-compile--process))
+  (let ((source (current-buffer))
+        (tmp-file (make-temp-file "+emacs-lisp-byte-compile-src"))
+        (out-buf (generate-new-buffer "+emacs-lisp-byte-compile-out")))
+    ;; write the content to a temp file
+    (save-restriction
+      (widen)
+      (write-region nil nil tmp-file nil 'nomessage))
+    ;; make the process
+    (setq +emacs-lisp-reduced-flymake-byte-compile--process
+          (make-process
+           :name "+emacs-reduced-flymake"
+           :noquery t
+           :connetion-type 'pipe
+           :buffer out-buf
+           :command `(,(expand-file-name invocation-name invocation-directory)
+                      "-Q"
+                      "--batch"
+                      ,@(mapcan (fn! (list "-L" %)) elisp-flymake-byte-compile-load-path)
+                      ;; this is what silences the byte compiler
+                      "--eval" ,(prin1-to-string `(setq doom-modules ',doom-modules
+                                                        doom-disabled-packages ',doom-disabled-packages
+                                                        byte-compile-warnings ',+emacs-lisp-linter-warnings)
+)
+                      "-f" "elisp-flymake--batch-compile-for-flymake"
+                      ,tmp-file)
+           :stderr "*stderr of +elisp-flymake-byte-compile-out*"
+           :sentinel
+           ;; deal with the process when it exits
+           (lambda (proc _event)
+             (when (memq (process-status proc) '(exit signal))
+               (unwind-protect
+                   (cond
+                    ;; if the buffer is dead or the process is not the same, log the process as old.
+                    ((or (not (buffer-live-p source))
+                         (not (with-current-buffer source (eq proc +emacs-lisp-reduced-flymake-byte-compile--process))))
+                     (flymake-log :warning "byte compile process %s is old" proc))
+                    ;; if the process exited without problem process the buffer
+                    ((zerop (process-exit-status proc))
+                     (elisp-flymake--byte-compile-done report-fn source out-buf))
+                    ;; otherwise something else horrid has gone wrong and we panic
+                    (t (funcall report-fn :panic
+                                :explanation
+                                (format "byte compile process %s died" proc))))
+                 ;; cleanup
+                 (ignore-errors (delete-file tmp-file))
+                 (kill-buffer out-buf))))))))
+
 ;;;###autoload
 (define-minor-mode +emacs-lisp-non-package-mode
-  "Reduce flycheck verbosity where it is appropriate.
+  "Reduce flycheck/flymake verbosity where it is appropriate.
 
 Essentially, this means in any elisp file that either:
 - Is not a theme in `custom-theme-load-path',
@@ -292,7 +354,7 @@ This generally applies to your private config (`doom-user-dir') or Doom's source
   :since "3.0.0"
   (unless (and (or (bound-and-true-p flycheck-mode)
                    (bound-and-true-p flymake-mode))
-           (not (+emacs-lisp--in-package-buffer-p)))
+               (not (+emacs-lisp--in-package-buffer-p)))
     (setq +emacs-lisp-non-package-mode nil))
   (when (derived-mode-p 'emacs-lisp-mode)
     (add-hook 'after-save-hook #'+emacs-lisp-non-package-mode nil t))
@@ -300,14 +362,17 @@ This generally applies to your private config (`doom-user-dir') or Doom's source
       (if (modulep! :checkers syntax +flymake)
           ;; flymake
           (progn
-            (add-hook 'flymake-diagnostic-functions #'elisp-flymake-checkdoc nil t))
-          ;; flycheck
-          (when (get 'flycheck-disabled-checkers 'initial-value)
-            (setq-local flycheck-disabled-checkers (get 'flycheck-disabled-checkers 'initial-value))
-            (kill-local-variable 'flycheck-emacs-lisp-check-form)))
+            (add-hook! 'flymake-diagnostic-functions :local #'elisp-flymake-checkdoc #'elisp-flymake-byte-compile)
+            (remove-hook 'flymake-diagnostic-functions #'+emacs-lisp-reduced-flymake-byte-compile))
+        ;; flycheck
+        (when (get 'flycheck-disabled-checkers 'initial-value)
+          (setq-local flycheck-disabled-checkers (get 'flycheck-disabled-checkers 'initial-value))
+          (kill-local-variable 'flycheck-emacs-lisp-check-form)))
     (if (modulep! :checkers syntax +flymake)
-      ;; flymake
-        (remove-hook 'flymake-diagnostic-functions #'elisp-flymake-checkdoc t)
+        ;; flymake
+        (progn
+          (remove-hook! 'flymake-diagnostic-functions :local #'elisp-flymake-checkdoc #'elisp-flymake-byte-compile)
+          (add-hook 'flymake-diagnostic-functions #'+emacs-lisp-reduced-flymake-byte-compile))
       ;; flycheck
       (with-memoization (get 'flycheck-disabled-checkers 'initial-value)
         flycheck-disabled-checkers)