emacs/lisp/progmodes/elisp-mode.el

;;; elisp-mode.el --- Emacs Lisp mode  -*- lexical-binding:t -*-

;; Copyright (C) 1985-1986, 1999-2021 Free Software Foundation, Inc.

;; Maintainer: emacs-devel@gnu.org
;; Keywords: lisp, languages
;; Package: emacs

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; The major mode for editing Emacs Lisp code.
;; This mode is documented in the Emacs manual.

;;; Code:

(require 'cl-generic)
(require 'lisp-mode)
(eval-when-compile (require 'cl-lib))

(define-abbrev-table 'emacs-lisp-mode-abbrev-table ()
  "Abbrev table for Emacs Lisp mode.
It has `lisp-mode-abbrev-table' as its parent."
  :parents (list lisp-mode-abbrev-table))

(defvar emacs-lisp-mode-syntax-table
  (let ((table (make-syntax-table lisp-data-mode-syntax-table)))
    ;; These are redundant, now.
    ;;(modify-syntax-entry ?\[ "(]  " table)
    ;;(modify-syntax-entry ?\] ")[  " table)
    table)
  "Syntax table used in `emacs-lisp-mode'.")

(defvar emacs-lisp-mode-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map lisp-mode-shared-map)
    (define-key map "\e\t" 'completion-at-point)
    (define-key map "\e\C-x" 'eval-defun)
    (define-key map "\e\C-q" 'indent-pp-sexp)
    map)
  "Keymap for Emacs Lisp mode.
All commands in `lisp-mode-shared-map' are inherited by this map.")

(easy-menu-define emacs-lisp-mode-menu emacs-lisp-mode-map
  "Menu for Emacs Lisp mode."
  '("Emacs-Lisp"
    ["Indent Line" lisp-indent-line]
    ["Indent Region" indent-region
     :help "Indent each nonblank line in the region"
     :active mark-active]
    ["Comment Out Region" comment-region
     :help "Comment or uncomment each line in the region"
     :active mark-active]
    "---"
    ["Evaluate Last S-expression" eval-last-sexp
     :help "Evaluate sexp before point; print value in echo area"]
    ["Evaluate Region" eval-region
     :help "Execute the region as Lisp code"
     :active mark-active]
    ["Evaluate Buffer" eval-buffer
     :help "Execute the current buffer as Lisp code"]
    ["Interactive Expression Evaluation" ielm
     :help "Interactively evaluate Emacs Lisp expressions"]
    "---"
    ["Byte-compile This File" emacs-lisp-byte-compile
     :help "Byte compile the file containing the current buffer"]
    ["Byte-compile and Load" emacs-lisp-byte-compile-and-load
     :help "Byte-compile the current file (if it has changed), then load compiled code"]
    ["Byte-recompile Directory..." byte-recompile-directory
     :help "Recompile every `.el' file in DIRECTORY that needs recompilation"]
    ["Disassemble Byte Compiled Object..." disassemble
     :help "Print disassembled code for OBJECT in a buffer"]
    "---"
    ["Instrument Function for Debugging" edebug-defun
     :help "Evaluate the top level form point is in, stepping through with Edebug"
     :keys "C-u C-M-x"]
    ("Navigation"
     ["Forward Sexp" forward-sexp
      :help "Go to the next s-expression"]
     ["Backward Sexp" backward-sexp
      :help "Go to the previous s-expression"]
     ["Beginning Of Defun" beginning-of-defun
      :help "Go to the start of the current function definition"]
     ["Up List" up-list
      :help "Go one level up and forward"])
    ("Linting"
     ["Lint Defun" elint-defun
      :help "Lint the function at point"]
     ["Lint Buffer" elint-current-buffer
      :help "Lint the current buffer"]
     ["Lint File..." elint-file
      :help "Lint a file"]
     ["Lint Directory..." elint-directory
      :help "Lint a directory"])
    ("Profiling"
     ;; Maybe this should be in a separate submenu from the ELP stuff?
     ["Start Native Profiler..." profiler-start
      :help "Start recording profiling information"]
     ["Show Profiler Report" profiler-report
      :help "Show the current profiler report"
      :active (and (featurep 'profiler)
                   (profiler-running-p))]
     ["Stop Native Profiler" profiler-stop
      :help "Stop recording profiling information"
      :active (and (featurep 'profiler)
                   (profiler-running-p))]
     "---"
     ["Instrument Function..." elp-instrument-function
      :help "Instrument a function for profiling"]
     ["Instrument Package..." elp-instrument-package
      :help "Instrument for profiling all function that start with a prefix"]
     ["Show Profiling Results" elp-results
      :help "Display current profiling results"]
     ["Reset Counters for Function..." elp-reset-function
      :help "Reset the profiling information for a function"]
     ["Reset Counters for All Functions" elp-reset-all
      :help "Reset the profiling information for all functions being profiled"]
     "---"
     ["Remove Instrumentation for All Functions" elp-restore-all
      :help "Restore the original definitions of all functions being profiled"]
     ["Remove Instrumentation for Function..." elp-restore-function
      :help "Restore an instrumented function to its original definition"])
    ("Tracing"
     ["Trace Function..." trace-function
      :help "Trace the function given as an argument"]
     ["Trace Function Quietly..." trace-function-background
      :help "Trace the function with trace output going quietly to a buffer"]
     "---"
     ["Untrace All" untrace-all
      :help "Untrace all currently traced functions"]
     ["Untrace Function..." untrace-function
      :help "Untrace function, and possibly activate all remaining advice"])
    ["Construct Regexp" re-builder
     :help "Construct a regexp interactively"]
    ["Check Documentation Strings" checkdoc
     :help "Check documentation strings for style requirements"]
    ["Auto-Display Documentation Strings" eldoc-mode
     :help "Display the documentation string for the item under cursor"
     :style toggle
     :selected (bound-and-true-p eldoc-mode)]))

(defun elisp-context-menu (menu click)
  (define-key-after menu [elisp-separator] menu-bar-separator
    'mark-whole-buffer)
  (when (thing-at-mouse click 'symbol)
    (define-key-after menu [describe-symbol]
      '(menu-item "Describe Symbol"
                  (lambda (click) (interactive "e")
                    (describe-symbol
                     (intern (thing-at-mouse click 'symbol t))))
                  :help "Display the full documentation of symbol")
      'elisp-separator)
    (define-key-after menu [info-lookup-symbol]
      '(menu-item "Lookup Symbol"
                  (lambda (click) (interactive "e")
                    (info-lookup-symbol
                     (intern (thing-at-mouse click 'symbol t))))
                  :help "Display definition in relevant manual")
      'describe-symbol))
  menu)

(defun emacs-lisp-byte-compile ()
  "Byte compile the file containing the current buffer."
  (interactive nil emacs-lisp-mode)
  (if buffer-file-name
      (byte-compile-file buffer-file-name)
    (error "The buffer must be saved in a file first")))

(defun emacs-lisp--before-compile-buffer ()
  "Make sure the buffer is saved before compiling."
  (or buffer-file-name
      (error "The buffer must be saved in a file first"))
  ;; Recompile if file or buffer has changed since last compilation.
  (if (and (buffer-modified-p)
	   (y-or-n-p (format "Save buffer %s first? " (buffer-name))))
      (save-buffer)))

(defun emacs-lisp-byte-compile-and-load ()
  "Byte-compile the current file (if it has changed), then load compiled code."
  (interactive nil emacs-lisp-mode)
  (emacs-lisp--before-compile-buffer)
  (require 'bytecomp)
  (byte-recompile-file buffer-file-name nil 0)
  (load buffer-file-name))

(declare-function native-compile "comp")
(defun emacs-lisp-native-compile-and-load ()
  "Native-compile synchronously the current file (if it has changed).
Load the compiled code when finished.

Use `emacs-lisp-byte-compile-and-load' in combination with
`native-comp-deferred-compilation' set to `t' to achieve asynchronous
native compilation."
  (interactive nil emacs-lisp-mode)
  (emacs-lisp--before-compile-buffer)
  (load (native-compile buffer-file-name)))

(defun emacs-lisp-macroexpand ()
  "Macroexpand the form after point.
Comments in the form will be lost."
  (interactive)
  (let* ((start (point))
         (exp (read (current-buffer)))
         ;; Compute it before, since it may signal errors.
         (new (macroexpand-1 exp)))
    (if (equal exp new)
        (message "Not a macro call, nothing to expand")
      (delete-region start (point))
      (pp new (current-buffer))
      (if (bolp) (delete-char -1))
      (indent-region start (point)))))

(defcustom emacs-lisp-mode-hook nil
  "Hook run when entering Emacs Lisp mode."
  :options '(eldoc-mode imenu-add-menubar-index checkdoc-minor-mode)
  :type 'hook
  :group 'lisp)

(defun emacs-lisp-set-electric-text-pairs ()
  "Set `electric-pair-text-pairs' for all `emacs-lisp-mode' buffers."
  (defvar electric-pair-text-pairs)
  (let ((elisp-pairs (append '((?\` . ?\') (?‘ . ?’))
                             electric-pair-text-pairs)))
    (save-current-buffer
      (dolist (buf (buffer-list))
        (set-buffer buf)
        (when (derived-mode-p 'emacs-lisp-mode)
          (setq-local electric-pair-text-pairs elisp-pairs)))))
  (remove-hook 'electric-pair-mode-hook #'emacs-lisp-set-electric-text-pairs))

(defun elisp-enable-lexical-binding (&optional interactive)
  "Make the current buffer use `lexical-binding'."
  (interactive "p")
  (if lexical-binding
      (when interactive
        (message "lexical-binding already enabled!")
        (ding))
    (when (or (not interactive)
              (y-or-n-p (format "Enable lexical-binding in this %s? "
                                (if buffer-file-name "file" "buffer"))))
      (setq-local lexical-binding t)
      (add-file-local-variable-prop-line 'lexical-binding t interactive))))

(defvar elisp--dynlex-modeline-map
  (let ((map (make-sparse-keymap)))
    (define-key map [mode-line mouse-1] 'elisp-enable-lexical-binding)
    map))

;;;###autoload
(define-derived-mode emacs-lisp-mode lisp-data-mode
  `("ELisp"
    (lexical-binding (:propertize "/l"
                      help-echo "Using lexical-binding mode")
                     (:propertize "/d"
                      help-echo "Using old dynamic scoping mode\n\
mouse-1: Enable lexical-binding mode"
		      face warning
		      mouse-face mode-line-highlight
                      local-map ,elisp--dynlex-modeline-map)))
  "Major mode for editing Lisp code to run in Emacs.
Commands:
Delete converts tabs to spaces as it moves back.
Blank lines separate paragraphs.  Semicolons start comments.

\\{emacs-lisp-mode-map}"
  :group 'lisp
  (defvar project-vc-external-roots-function)
  (setcar font-lock-defaults
          '(lisp-el-font-lock-keywords
            lisp-el-font-lock-keywords-1
            lisp-el-font-lock-keywords-2))
  (setf (nth 2 font-lock-defaults) nil)
  (add-hook 'after-load-functions #'elisp--font-lock-flush-elisp-buffers)
  (if (boundp 'electric-pair-text-pairs)
      (setq-local electric-pair-text-pairs
                  (append '((?\` . ?\') (?\‘ . ?\’))
                          electric-pair-text-pairs))
    (add-hook 'electric-pair-mode-hook #'emacs-lisp-set-electric-text-pairs))
  (add-hook 'eldoc-documentation-functions
            #'elisp-eldoc-funcall nil t)
  (add-hook 'eldoc-documentation-functions
            #'elisp-eldoc-var-docstring nil t)
  (add-hook 'xref-backend-functions #'elisp--xref-backend nil t)
  (setq-local project-vc-external-roots-function #'elisp-load-path-roots)
  (add-hook 'completion-at-point-functions
            #'elisp-completion-at-point nil 'local)
  (add-hook 'flymake-diagnostic-functions #'elisp-flymake-checkdoc nil t)
  (add-hook 'flymake-diagnostic-functions
              #'elisp-flymake-byte-compile nil t)
  (add-hook 'context-menu-functions #'elisp-context-menu 10 t))

;; Font-locking support.

(defun elisp--font-lock-flush-elisp-buffers (&optional file)
  ;; We're only ever called from after-load-functions, load-in-progress can
  ;; still be t in case of nested loads.
  (when (or (not load-in-progress) file)
    ;; FIXME: If the loaded file did not define any macros, there shouldn't
    ;; be any need to font-lock-flush all the Elisp buffers.
    (dolist (buf (buffer-list))
      (with-current-buffer buf
	(when (derived-mode-p 'emacs-lisp-mode)
          ;; So as to take into account new macros that may have been defined
          ;; by the just-loaded file.
	  (font-lock-flush))))))

;;; Completion at point for Elisp

(defun elisp--local-variables-1 (vars sexp)
  "Return the vars locally bound around the witness, or nil if not found."
  (let (res)
    (while
        (unless
            (setq res
                  (pcase sexp
                    (`(,(or 'let 'let*) ,bindings)
                     (let ((vars vars))
                       (when (eq 'let* (car sexp))
                         (dolist (binding (cdr (reverse bindings)))
                           (push (or (car-safe binding) binding) vars)))
                       (elisp--local-variables-1
                        vars (car (cdr-safe (car (last bindings)))))))
                    (`(,(or 'let 'let*) ,bindings . ,body)
                     (let ((vars vars))
                       (dolist (binding bindings)
                         (push (or (car-safe binding) binding) vars))
                       (elisp--local-variables-1 vars (car (last body)))))
                    (`(lambda ,_args)
                     ;; FIXME: Look for the witness inside `args'.
                     (setq sexp nil))
                    (`(lambda ,args . ,body)
                     (elisp--local-variables-1
                      (append (remq '&optional (remq '&rest args)) vars)
                      (car (last body))))
                    (`(condition-case ,_ ,e) (elisp--local-variables-1 vars e))
                    (`(condition-case ,v ,_ . ,catches)
                     (elisp--local-variables-1
                      (cons v vars) (cdr (car (last catches)))))
                    (`(quote . ,_)
                     ;; FIXME: Look for the witness inside sexp.
                     (setq sexp nil))
                    ;; FIXME: Handle `cond'.
                    (`(,_ . ,_)
                     (elisp--local-variables-1 vars (car (last sexp))))
                    ('elisp--witness--lisp (or vars '(nil)))
                    (_ nil)))
          ;; We didn't find the witness in the last element so we try to
          ;; backtrack to the last-but-one.
          (setq sexp (ignore-errors (butlast sexp)))))
    res))

(defvar warning-minimum-log-level)

(defun elisp--local-variables ()
  "Return a list of locally let-bound variables at point."
  (save-excursion
    (skip-syntax-backward "w_")
    (let* ((ppss (syntax-ppss))
           (txt (buffer-substring-no-properties (or (car (nth 9 ppss)) (point))
                                                (or (nth 8 ppss) (point))))
           (closer ()))
      (dolist (p (nth 9 ppss))
        (push (cdr (syntax-after p)) closer))
      (setq closer (apply #'string closer))
      (let* ((sexp (condition-case nil
                       (car (read-from-string
                             (concat txt "elisp--witness--lisp" closer)))
                     ((invalid-read-syntax end-of-file) nil)))
             (macroexpand-advice (lambda (expander form &rest args)
                                   (condition-case nil
                                       (apply expander form args)
                                     (error form))))
             (sexp
              (unwind-protect
                  (let ((warning-minimum-log-level :emergency))
                    (advice-add 'macroexpand :around macroexpand-advice)
                    (macroexpand-all sexp))
                (advice-remove 'macroexpand macroexpand-advice)))
             (vars (elisp--local-variables-1 nil sexp)))
        (delq nil
              (mapcar (lambda (var)
                        (and (symbolp var)
                             (not (string-match (symbol-name var) "\\`[&_]"))
                             ;; Eliminate uninterned vars.
                             (intern-soft var)
                             var))
                      vars))))))

(defvar elisp--local-variables-completion-table
  ;; Use `defvar' rather than `defconst' since defconst would purecopy this
  ;; value, which would doubly fail: it would fail because purecopy can't
  ;; handle the recursive bytecode object, and it would fail because it would
  ;; move `lastpos' and `lastvars' to pure space where they'd be immutable!
  (let ((lastpos nil) (lastvars nil))
    (letrec ((hookfun (lambda ()
                        (setq lastpos nil)
                        (remove-hook 'post-command-hook hookfun))))
      (completion-table-dynamic
       (lambda (_string)
         (save-excursion
           (skip-syntax-backward "_w")
           (let ((newpos (cons (point) (current-buffer))))
             (unless (equal lastpos newpos)
               (add-hook 'post-command-hook hookfun)
               (setq lastpos newpos)
               (setq lastvars
                     (mapcar #'symbol-name (elisp--local-variables))))))
         lastvars)))))

(defun elisp--expect-function-p (pos)
  "Return non-nil if the symbol at point is expected to be a function."
  (or
   (and (eq (char-before pos) ?')
        (eq (char-before (1- pos)) ?#))
   (save-excursion
     (let ((parent (nth 1 (syntax-ppss pos))))
       (when parent
         (goto-char parent)
         (and
          (looking-at (concat "(\\(cl-\\)?"
                              (regexp-opt '("declare-function"
                                            "function" "defadvice"
                                            "callf" "callf2"
                                            "defsetf"))
                              "[ \t\r\n]+"))
          (eq (match-end 0) pos)))))))

(defun elisp--form-quoted-p (pos)
  "Return non-nil if the form at POS is not evaluated.
It can be quoted, or be inside a quoted form."
  ;; FIXME: Do some macro expansion maybe.
  (save-excursion
    (let ((state (syntax-ppss pos)))
      (or (nth 8 state)   ; Code inside strings usually isn't evaluated.
          ;; FIXME: The 9th element is undocumented.
          (let ((nesting (cons (point) (reverse (nth 9 state))))
                res)
            (while (and nesting (not res))
              (goto-char (pop nesting))
              (cond
               ((or (eq (char-after) ?\[)
                    (progn
                      (skip-chars-backward " ")
                      (memq (char-before) '(?' ?` ?‘))))
                (setq res t))
               ((eq (char-before) ?,)
                (setq nesting nil))))
            res)))))

;; FIXME: Support for Company brings in features which straddle eldoc.
;; We should consolidate this, so that major modes can provide all that
;; data all at once:
;; - a function to extract "the reference at point" (may be more complex
;;     than a mere string, to distinguish various namespaces).
;; - a function to jump to such a reference.
;; - a function to show the signature/interface of such a reference.
;; - a function to build a help-buffer about that reference.
;; FIXME: Those functions should also be used by the normal completion code in
;; the *Completions* buffer.

(defun elisp--company-doc-buffer (str)
  (let ((symbol (intern-soft str)))
    ;; FIXME: we really don't want to "display-buffer and then undo it".
    (save-window-excursion
      ;; Make sure we don't display it in another frame, otherwise
      ;; save-window-excursion won't be able to undo it.
      (let ((display-buffer-overriding-action
             '(nil . ((inhibit-switch-frame . t)))))
        (ignore-errors
          (cond
           ((fboundp symbol) (describe-function symbol))
           ((boundp symbol) (describe-variable symbol))
           ((featurep symbol) (describe-package symbol))
           ((facep symbol) (describe-face symbol))
           (t (signal 'user-error nil)))
          (help-buffer))))))

(defun elisp--company-doc-string (str)
  (let* ((symbol (intern-soft str))
         (doc (if (fboundp symbol)
                  (documentation symbol t)
                (documentation-property symbol 'variable-documentation t))))
    (and (stringp doc)
         (string-match ".*$" doc)
         (match-string 0 doc))))

;; can't (require 'find-func) in a preloaded file
(declare-function find-library-name "find-func" (library))
(declare-function find-function-library "find-func" (function &optional l-o v))

(defun elisp--company-location (str)
  (let ((sym (intern-soft str)))
    (cond
     ((fboundp sym) (find-definition-noselect sym nil))
     ((boundp sym) (find-definition-noselect sym 'defvar))
     ((featurep sym)
      (require 'find-func)
      (cons (find-file-noselect (find-library-name
                                 (symbol-name sym)))
            0))
     ((facep sym) (find-definition-noselect sym 'defface)))))

(defun elisp-completion-at-point ()
  "Function used for `completion-at-point-functions' in `emacs-lisp-mode'.
If the context at point allows only a certain category of
symbols (e.g. functions, or variables) then the returned
completions are restricted to that category.  In contexts where
any symbol is possible (following a quote, for example),
functions are annotated with \"<f>\" via the
`:annotation-function' property."
  (with-syntax-table emacs-lisp-mode-syntax-table
    (let* ((pos (point))
	   (beg (condition-case nil
		    (save-excursion
		      (backward-sexp 1)
		      (skip-chars-forward "`',‘#")
		      (point))
		  (scan-error pos)))
	   (end
	    (unless (or (eq beg (point-max))
			(member (char-syntax (char-after beg))
                                '(?\" ?\()))
	      (condition-case nil
		  (save-excursion
		    (goto-char beg)
		    (forward-sexp 1)
                    (skip-chars-backward "'’")
		    (when (>= (point) pos)
		      (point)))
		(scan-error pos))))
           ;; t if in function position.
           (funpos (eq (char-before beg) ?\())
           (quoted (elisp--form-quoted-p beg))
           (fun-sym (condition-case nil
                        (save-excursion
                          (up-list -1)
                          (forward-char 1)
                          (and (memq (char-syntax (char-after)) '(?w ?_))
                               (read (current-buffer))))
                      (error nil))))
      (when (and end (or (not (nth 8 (syntax-ppss)))
                         (memq (char-before beg) '(?` ?‘))))
        (let ((table-etc
               (if (or (not funpos) quoted)
                   (cond
                    ;; FIXME: We could look at the first element of
                    ;; the current form and use it to provide a more
                    ;; specific completion table in more cases.
                    ((eq fun-sym 'ignore-error)
                     (list t obarray
                           :predicate (lambda (sym)
                                        (get sym 'error-conditions))))
                    ((elisp--expect-function-p beg)
                     (list nil obarray
                           :predicate #'fboundp
                           :company-kind #'elisp--company-kind
                           :company-doc-buffer #'elisp--company-doc-buffer
                           :company-docsig #'elisp--company-doc-string
                           :company-location #'elisp--company-location))
                    (quoted
                     (list nil obarray
                           ;; Don't include all symbols (bug#16646).
                           :predicate (lambda (sym)
                                        (or (boundp sym)
                                            (fboundp sym)
                                            (featurep sym)
                                            (symbol-plist sym)))
                           :annotation-function
                           (lambda (str) (if (fboundp (intern-soft str)) " <f>"))
                           :company-kind #'elisp--company-kind
                           :company-doc-buffer #'elisp--company-doc-buffer
                           :company-docsig #'elisp--company-doc-string
                           :company-location #'elisp--company-location))
                    (t
                     (list nil (completion-table-merge
                                elisp--local-variables-completion-table
                                (apply-partially #'completion-table-with-predicate
                                                 obarray
                                                 #'boundp
                                                 'strict))
                           :company-kind
                           (lambda (s)
                             (if (test-completion s elisp--local-variables-completion-table)
                                 'value
                               'variable))
                           :company-doc-buffer #'elisp--company-doc-buffer
                           :company-docsig #'elisp--company-doc-string
                           :company-location #'elisp--company-location)))
                 ;; Looks like a funcall position.  Let's double check.
                 (save-excursion
                   (goto-char (1- beg))
                   (let ((parent
                          (condition-case nil
                              (progn (up-list -1) (forward-char 1)
                                     (let ((c (char-after)))
                                       (if (eq c ?\() ?\(
                                         (if (memq (char-syntax c) '(?w ?_))
                                             (read (current-buffer))))))
                            (error nil))))
                     (pcase parent
                       ;; FIXME: Rather than hardcode special cases here,
                       ;; we should use something like a symbol-property.
                       ('declare
                        (list t (mapcar (lambda (x) (symbol-name (car x)))
                                        (delete-dups
                                         ;; FIXME: We should include some
                                         ;; docstring with each entry.
                                         (append macro-declarations-alist
                                                 defun-declarations-alist
                                                 nil))))) ; Copy both alists.
                       ((and (or 'condition-case 'condition-case-unless-debug)
                             (guard (save-excursion
                                      (ignore-errors
                                        (forward-sexp 2)
                                        (< (point) beg)))))
                        (list t obarray
                              :predicate (lambda (sym) (get sym 'error-conditions))))
                       ;; `ignore-error' with a list CONDITION parameter.
                       ('ignore-error
                        (list t obarray
                              :predicate (lambda (sym)
                                           (get sym 'error-conditions))))
                       ((and (or ?\( 'let 'let*)
                             (guard (save-excursion
                                      (goto-char (1- beg))
                                      (when (eq parent ?\()
                                        (up-list -1))
                                      (forward-symbol -1)
                                      (looking-at "\\_<let\\*?\\_>"))))
                        (list t obarray
                              :predicate #'boundp
                              :company-kind (lambda (_) 'variable)
                              :company-doc-buffer #'elisp--company-doc-buffer
                              :company-docsig #'elisp--company-doc-string
                              :company-location #'elisp--company-location))
                       (_ (list nil obarray
                                :predicate #'fboundp
                                :company-kind #'elisp--company-kind
                                :company-doc-buffer #'elisp--company-doc-buffer
                                :company-docsig #'elisp--company-doc-string
                                :company-location #'elisp--company-location
                                ))))))))
          (nconc (list beg end)
                 (if (null (car table-etc))
                     (cdr table-etc)
                   (cons
                    (if (memq (char-syntax (or (char-after end) ?\s))
                              '(?\s ?>))
                        (cadr table-etc)
                      (apply-partially 'completion-table-with-terminator
                                       " " (cadr table-etc)))
                    (cddr table-etc)))))))))

(defun elisp--company-kind (str)
  (let ((sym (intern-soft str)))
    (cond
     ((or (macrop sym) (special-form-p sym)) 'keyword)
     ((fboundp sym) 'function)
     ((boundp sym) 'variable)
     ((featurep sym) 'module)
     ((facep sym) 'color)
     (t 'text))))

(defun lisp-completion-at-point (&optional _predicate)
  (declare (obsolete elisp-completion-at-point "25.1"))
  (elisp-completion-at-point))

;;; Xref backend

(declare-function xref-make "xref" (summary location))
(declare-function xref-item-location "xref" (this))

(defun elisp--xref-backend () 'elisp)

;; WORKAROUND: This is nominally a constant, but the text properties
;; are not preserved thru dump if use defconst.  See bug#21237.
(defvar elisp--xref-format
  #("(%s %s)"
    1 3 (face font-lock-keyword-face)
    4 6 (face font-lock-function-name-face)))

;; WORKAROUND: This is nominally a constant, but the text properties
;; are not preserved thru dump if use defconst.  See bug#21237.
(defvar elisp--xref-format-extra
  #("(%s %s %s)"
    1 3 (face font-lock-keyword-face)
    4 6 (face font-lock-function-name-face)))

(defvar find-feature-regexp);; in find-func.el

(defun elisp--xref-make-xref (type symbol file &optional summary)
  "Return an xref for TYPE SYMBOL in FILE.
TYPE must be a type in `find-function-regexp-alist' (use nil for
'defun).  If SUMMARY is non-nil, use it for the summary;
otherwise build the summary from TYPE and SYMBOL."
  (xref-make (or summary
		 (format elisp--xref-format (or type 'defun) symbol))
	     (xref-make-elisp-location symbol type file)))

(defvar elisp-xref-find-def-functions nil
  "List of functions run from `elisp--xref-find-definitions' to add more xrefs.
Called with one arg; the symbol whose definition is desired.
Each function should return a list of xrefs, or nil; the first
non-nil result supersedes the xrefs produced by
`elisp--xref-find-definitions'.")

(defun elisp--xref-list-index ()
  "Return the list index of the form at point, moving to the start.
If the buffer start was reached, return nil."
  (let ((i 0))
    (while (condition-case nil
               (let ((pt (point)))
                 (backward-sexp)
                 (< (point) pt))
             (scan-error nil))
      (setq i (1+ i)))
    (and (not (bobp)) i)))

(defun elisp--xref-infer-namespace (pos)
  "Find the likely namespace of the identifier at POS.
Return one of `function', `variable' `maybe-variable', `feature', `face', or
`any' (indicating any namespace).  `maybe-variable' indicates a variable
namespace but with lower confidence."
  (save-excursion
    (goto-char pos)
    (cl-flet ((looking-at-sym ()
                (let ((val (save-excursion
                             (ignore-errors (read (current-buffer))))))
                  (and (symbolp val) val))))
      (cond
       ((and (eq (char-before pos) ?\')
             (eq (char-before (1- pos)) ?#))
        ;; #'IDENT
        'function)
       ((memq (char-before pos) '(?\' ?`))
        ;; 'IDENT or `IDENT -- try to disambiguate.
        (backward-char)                 ; Step over '
        (let ((i (elisp--xref-list-index))
              (sym (looking-at-sym)))
          (cond
           ((eql i 1)
            (cond
             ((memq sym '( featurep require provide))
              'feature)
             ((memq sym
                    '(
                      ;; We are mostly interested in functions that take a
                      ;; function symbol as argument:
                      fboundp symbol-function fset
                      ;; ... but we include some common higher-order functions
                      ;; as well, even though the argument really should
                      ;; be #'-quoted:
                      function-get function-put
                      func-arity functionp
                      funcall funcall-interactively
                      apply mapcar mapc mapcan mapconcat
                      apply-partially
                      substitute-key-definition))
              'function)
             ((memq sym
                    '(
                      ;; Functions taking a variable symbol as first argument.
                      ;; More of these could be added for greater precision.
                      boundp set symbol-value
                      special-variable-p local-variable-p
                      local-variable-if-set-p
                      make-variable-buffer-local
                      default-value set-default make-local-variable
                      buffer-local-value))
              'variable)
             ((memq sym
                    '(
                      ;; FIXME: Add more functions taking a face
                      ;; symbol for greater precision.
                      facep face-name face-id))
              'face)
             (t 'any)))
           ((and (eql i 2)
                 (memq sym '( global-set-key local-set-key
                              substitute-key-definition
                              add-hook)))
            'function)
           ((and (eql i 3)
                 (memq sym '( define-key add-function)))
            'function)
           (t 'any))))
       ((or (and (eq (char-before (1- pos)) ?,)
                 (eq (char-before pos) ?@))
            (eq (char-before pos) ?,))
        ;; ,IDENT or ,@IDENT
        'variable)
       (t
        ;; Unquoted name -- look at the context.  General scheme:
        ;; (K-HEAD ... (J-HEAD ... (I-HEAD ... IDENT
        ;;             ^ index K   ^ index J   ^ index I
        (let* ((i (elisp--xref-list-index))
               (i-head (looking-at-sym))
               (i-paren (and i-head (eq (char-before) ?\()
                             (progn (backward-char) t)))
               (i-quoted (and i-paren (memq (char-before) '(?\' ?`))))
               (j (and i-paren (elisp--xref-list-index)))
               (j-head (and j (looking-at-sym)))
               (j-paren (and j-head (eq (char-before) ?\()
                             (progn (backward-char) t)))
               (j-quoted (and j-paren (memq (char-before) '(?\' ?`))))
               (k (and j-paren (elisp--xref-list-index)))
               (k-head (and k (looking-at-sym)))
               (k-paren (and k-head (eq (char-before) ?\()
                             (progn (backward-char) t)))
               (k-quoted (and k-paren (memq (char-before) '(?\' ?`)))))
          (cond
           ((or i-quoted j-quoted k-quoted)
            ;; '(... IDENT or '(... (... IDENT or '(... (... (... IDENT
            'any)
           ((and (eql j 1)
                 (memq j-head '( let let* letrec dlet lambda)))
            ;; (let (... IDENT
            'variable)
           ((and (eql j 2)
                 (memq j-head '( defun defmacro defsubst
                                 define-inline declare-function
                                 defadvice
                                 cl-defmethod cl-defgeneric)))
            ;; (defun FUNC (... IDENT
            'variable)
           ((eq j-head 'cond)
            ;; (cond ... (... IDENT
            'variable)
           ((and (eql k 1)
                 (memq k-head '( let let* letrec dlet )))
            ;; (let (... (... IDENT
            'variable)
           ((eql i 0)
            ;; (IDENT ...
            'function)
           ((functionp i-head)
            ;; (FUNC ... IDENT
            'variable)
           ((and (eql i 1)
                 (cond
                  ((memq i-head '( function
                                   defun defmacro defsubst
                                   define-inline declare-function
                                   defadvice
                                   cl-defmethod cl-defgeneric))
                   'function)
                  ((memq i-head '( defvar defvar-local defconst defcustom))
                   'variable)
                  ((eq i-head 'defface)
                   'face))))
           ((memq i-head '( if while and or when unless progn prog1
                            let let* lambda defun defsubst defvar defconst))
            ;; arg to some common non-function forms
            'variable)
           ;; Anything else: probably a variable, but since i-head may be
           ;; a macro we cannot be sure.
           (t 'maybe-variable))))))))

(cl-defmethod xref-backend-identifier-at-point ((_backend (eql 'elisp)))
  (let ((bounds (bounds-of-thing-at-point 'symbol)))
    (and bounds
         (let ((ident (buffer-substring-no-properties
                       (car bounds) (cdr bounds))))
           ;; Use a property to transport the location of the identifier.
           (propertize ident 'pos (car bounds))))))

(cl-defmethod xref-backend-definitions ((_backend (eql 'elisp)) identifier)
  (require 'find-func)
  (let ((sym (intern-soft identifier)))
    (when sym
      (let* ((pos (get-text-property 0 'pos identifier))
             (namespace (if pos
                            (elisp--xref-infer-namespace pos)
                          'any))
             (defs (elisp--xref-find-definitions sym)))
        (if (eq namespace 'maybe-variable)
            (or (elisp--xref-filter-definitions defs 'variable sym)
                (elisp--xref-filter-definitions defs 'any sym))
          (elisp--xref-filter-definitions defs namespace sym))))))

(defun elisp--xref-filter-definitions (definitions namespace symbol)
  (if (eq namespace 'any)
      (if (memq symbol minor-mode-list)
          ;; The symbol is a minor mode. These should be defined by
          ;; "define-minor-mode", which means the variable and the
          ;; function are declared in the same place. So we return only
          ;; the function, arbitrarily.
          ;;
          ;; There is an exception, when the variable is defined in C
          ;; code, as for abbrev-mode.
          (cl-loop for d in definitions
                   for loc = (xref-item-location d)
                   for file = (xref-elisp-location-file loc)
                   when (or (not (eq (xref-elisp-location-type loc) 'defvar))
                            (null file)
                            (string-prefix-p "src/" file))
                   collect d)
        definitions)
    (let ((expected-types
           (pcase-exhaustive namespace
             ('function '( nil defalias define-type
                           cl-defgeneric cl-defmethod))
             ('variable '(defvar))
             ('face '(defface))
             ('feature '(feature)))))
      (cl-loop for d in definitions
               when (memq
                     (xref-elisp-location-type (xref-item-location d))
                     expected-types)
               collect d))))

(defun elisp--xref-find-definitions (symbol)
  ;; The file name is not known when `symbol' is defined via interactive eval.
  (let (xrefs)
    (let ((temp elisp-xref-find-def-functions))
      (while (and (null xrefs)
                  temp)
        (setq xrefs (append xrefs (funcall (pop temp) symbol)))))

    (unless xrefs
      ;; alphabetical by result type symbol

      ;; FIXME: advised function; list of advice functions
      ;; FIXME: aliased variable

      ;; Coding system symbols do not appear in ‘load-history’,
      ;; so we can’t get a location for them.

      (when (and (symbolp symbol)
                 (symbol-function symbol)
                 (symbolp (symbol-function symbol)))
        ;; aliased function
        (let* ((alias-symbol symbol)
               (alias-file (symbol-file alias-symbol))
               (real-symbol  (symbol-function symbol))
               (real-file (find-lisp-object-file-name real-symbol 'defun)))

          (when real-file
            (push (elisp--xref-make-xref nil real-symbol real-file) xrefs))

          (when alias-file
            (push (elisp--xref-make-xref 'defalias alias-symbol alias-file) xrefs))))

      (when (facep symbol)
        (let ((file (find-lisp-object-file-name symbol 'defface)))
          (when file
            (push (elisp--xref-make-xref 'defface symbol file) xrefs))))

      (when (fboundp symbol)
        (let ((file (find-lisp-object-file-name symbol (symbol-function symbol)))
              generic doc)
          (when file
            (cond
             ((eq file 'C-source)
              ;; First call to find-lisp-object-file-name for an object
              ;; defined in C; the doc strings from the C source have
              ;; not been loaded yet.  Second call will return "src/*.c"
              ;; in file; handled by 't' case below.
              (push (elisp--xref-make-xref nil symbol (help-C-file-name (symbol-function symbol) 'subr)) xrefs))

             ((and (setq doc (documentation symbol t))
                   ;; This doc string is defined in cl-macs.el cl-defstruct
                   (string-match "Constructor for objects of type `\\(.*\\)'" doc))
              ;; `symbol' is a name for the default constructor created by
              ;; cl-defstruct, so return the location of the cl-defstruct.
              (let* ((type-name (match-string 1 doc))
                     (type-symbol (intern type-name))
                     (file (find-lisp-object-file-name type-symbol 'define-type))
                     (summary (format elisp--xref-format-extra
                                      'cl-defstruct
                                      (concat "(" type-name)
                                      (concat "(:constructor " (symbol-name symbol) "))"))))
                (push (elisp--xref-make-xref 'define-type type-symbol file summary) xrefs)
                ))

             ((setq generic (cl--generic symbol))
              ;; FIXME: move this to elisp-xref-find-def-functions, in cl-generic.el

              ;; A generic function. If there is a default method, it
              ;; will appear in the method table, with no
              ;; specializers.
              ;;
              ;; If the default method is declared by the cl-defgeneric
              ;; declaration, it will have the same location as the
              ;; cl-defgeneric, so we want to exclude it from the
              ;; result. In this case, it will have a null doc
              ;; string. User declarations of default methods may also
              ;; have null doc strings, but we hope that is
              ;; rare. Perhaps this heuristic will discourage that.
              (dolist (method (cl--generic-method-table generic))
                (let* ((info (cl--generic-method-info method));; qual-string combined-args doconly
                       (specializers (cl--generic-method-specializers method))
                       (non-default nil)
                       (met-name (cl--generic-load-hist-format
                                  symbol
                                  (cl--generic-method-qualifiers method)
                                  specializers))
                       (file (find-lisp-object-file-name met-name 'cl-defmethod)))
                  (dolist (item specializers)
                    ;; default method has all 't' in specializers
                    (setq non-default (or non-default (not (equal t item)))))

                  (when (and file
                             (or non-default
                                 (nth 2 info))) ;; assuming only co-located default has null doc string
                    (if specializers
                        (let ((summary (format elisp--xref-format-extra 'cl-defmethod symbol (nth 1 info))))
                          (push (elisp--xref-make-xref 'cl-defmethod met-name file summary) xrefs))

                      (let ((summary (format elisp--xref-format-extra 'cl-defmethod symbol "()")))
                        (push (elisp--xref-make-xref 'cl-defmethod met-name file summary) xrefs))))
                  ))

              (if (and (setq doc (documentation symbol t))
                       ;; This doc string is created somewhere in
                       ;; cl--generic-make-function for an implicit
                       ;; defgeneric.
                       (string-match "\n\n(fn ARG &rest ARGS)" doc))
                  ;; This symbol is an implicitly defined defgeneric, so
                  ;; don't return it.
                  nil
                (push (elisp--xref-make-xref 'cl-defgeneric symbol file) xrefs))
              )

             (t
              (push (elisp--xref-make-xref nil symbol file) xrefs))
             ))))

      (when (boundp symbol)
        ;; A variable
        (let ((file (find-lisp-object-file-name symbol 'defvar)))
          (when file
            (cond
             ((eq file 'C-source)
              ;; The doc strings from the C source have not been loaded
              ;; yet; help-C-file-name does that.  Second call will
              ;; return "src/*.c" in file; handled below.
              (push (elisp--xref-make-xref 'defvar symbol (help-C-file-name symbol 'var)) xrefs))

             (t
              (push (elisp--xref-make-xref 'defvar symbol file) xrefs))

             ))))

      (when (featurep symbol)
        (let ((file (ignore-errors
                      (find-library-name (symbol-name symbol)))))
          (when file
            (push (elisp--xref-make-xref 'feature symbol file) xrefs))))
      );; 'unless xrefs'

    xrefs))

(declare-function xref-apropos-regexp "xref" (pattern))

(cl-defmethod xref-backend-apropos ((_backend (eql 'elisp)) pattern)
  (apply #'nconc
         (let ((regexp (xref-apropos-regexp pattern))
               lst)
           (dolist (sym (apropos-internal regexp))
             (push (elisp--xref-find-definitions sym) lst))
           (nreverse lst))))

(defvar elisp--xref-identifier-completion-table
  (apply-partially #'completion-table-with-predicate
                   obarray
                   (lambda (sym)
                     (or (boundp sym)
                         (fboundp sym)
                         (featurep sym)
                         (facep sym)))
                   'strict))

(cl-defmethod xref-backend-identifier-completion-table ((_backend
                                                         (eql 'elisp)))
  elisp--xref-identifier-completion-table)

(cl-defstruct (xref-elisp-location
               (:constructor xref-make-elisp-location (symbol type file)))
  "Location of an Emacs Lisp symbol definition."
  symbol type file)

(cl-defmethod xref-location-marker ((l xref-elisp-location))
  (pcase-let (((cl-struct xref-elisp-location symbol type file) l))
    (let ((buffer-point (find-function-search-for-symbol symbol type file)))
      (with-current-buffer (car buffer-point)
        (save-excursion
          (save-restriction
            (widen)
            (goto-char (or (cdr buffer-point) (point-min)))
            (point-marker)))))))

(cl-defmethod xref-location-group ((l xref-elisp-location))
  (let ((file (xref-elisp-location-file l)))
    (defvar find-function-C-source-directory)
    (if (and find-function-C-source-directory
             (string-match-p "\\`src/" file))
        (concat find-function-C-source-directory
                (substring file 3))
      file)))

(defun elisp-load-path-roots ()
  (if (boundp 'package-user-dir)
      (cons package-user-dir load-path)
    load-path))

;;; Elisp Interaction mode

(defvar lisp-interaction-mode-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map lisp-mode-shared-map)
    (define-key map "\e\C-x" 'eval-defun)
    (define-key map "\e\C-q" 'indent-pp-sexp)
    (define-key map "\e\t" 'completion-at-point)
    (define-key map "\n" 'eval-print-last-sexp)
    map)
  "Keymap for Lisp Interaction mode.
All commands in `lisp-mode-shared-map' are inherited by this map.")

(easy-menu-define lisp-interaction-mode-menu lisp-interaction-mode-map
  "Menu for Lisp Interaction mode."
  '("Lisp-Interaction"
    ["Complete Lisp Symbol" completion-at-point
     :help "Perform completion on Lisp symbol preceding point"]
    ["Indent or Pretty-Print" indent-pp-sexp
     :help "Indent each line of the list starting just after point, or prettyprint it"]
    ["Instrument Function for Debugging" edebug-defun
     :help "Evaluate the top level form point is in, stepping through with Edebug"
     :keys "C-u C-M-x"]
    ["Evaluate and Print" eval-print-last-sexp
     :help "Evaluate sexp before point; print value into current buffer"]
    ["Evaluate Defun" eval-defun
     :help "Evaluate the top-level form containing point, or after point"]))

(define-derived-mode lisp-interaction-mode emacs-lisp-mode "Lisp Interaction"
  "Major mode for typing and evaluating Lisp forms.
Like Lisp mode except that \\[eval-print-last-sexp] evals the Lisp expression
before point, and prints its value into the buffer, advancing point.
Note that printing is controlled by `eval-expression-print-length'
and `eval-expression-print-level'.

Commands:
Delete converts tabs to spaces as it moves back.
Paragraphs are separated only by blank lines.
Semicolons start comments.

\\{lisp-interaction-mode-map}"
  :abbrev-table nil
  (setq-local lexical-binding t))

;;; Emacs Lisp Byte-Code mode

(eval-and-compile
  (defconst emacs-lisp-byte-code-comment-re
    (concat "\\(#\\)@\\([0-9]+\\) "
            ;; Make sure it's a docstring and not a lazy-loaded byte-code.
            "\\(?:[^(]\\|([^\"]\\)")
    "Regular expression matching a dynamic doc string comment."))

(defun elisp--byte-code-comment (end &optional _point)
  "Try to syntactically mark the #@NNN ....^_ docstrings in byte-code files."
  (let ((ppss (syntax-ppss)))
    (when (and (nth 4 ppss)
               (eq (char-after (nth 8 ppss)) ?#))
      (let* ((n (save-excursion
                  (goto-char (nth 8 ppss))
                  (when (looking-at emacs-lisp-byte-code-comment-re)
                    (string-to-number (match-string 2)))))
             ;; `maxdiff' tries to make sure the loop below terminates.
             (maxdiff n))
        (when n
          (let* ((bchar (match-end 2))
                 (b (position-bytes bchar)))
            (goto-char (+ b n))
            (while (let ((diff (- (position-bytes (point)) b n)))
                     (unless (zerop diff)
                       (when (> diff maxdiff) (setq diff maxdiff))
                       (forward-char (- diff))
                       (setq maxdiff (if (> diff 0) diff
                                       (max (1- maxdiff) 1)))
                       t))))
          (if (<= (point) end)
              (put-text-property (1- (point)) (point)
                                 'syntax-table
                                 (string-to-syntax "> b"))
            (goto-char end)))))))

(defun elisp-byte-code-syntax-propertize (start end)
  (goto-char start)
  (elisp--byte-code-comment end (point))
  (funcall
   (syntax-propertize-rules
    (emacs-lisp-byte-code-comment-re
     (1 (prog1 "< b" (elisp--byte-code-comment end (point))))))
   start end))

;;;###autoload
(add-to-list 'auto-mode-alist '("\\.elc\\'" . elisp-byte-code-mode))
;;;###autoload
(define-derived-mode elisp-byte-code-mode emacs-lisp-mode
  "Elisp-Byte-Code"
  "Major mode for *.elc files."
  ;; TODO: Add way to disassemble byte-code under point.
  (setq-local open-paren-in-column-0-is-defun-start nil)
  (setq-local syntax-propertize-function
              #'elisp-byte-code-syntax-propertize))


;;; Globally accessible functionality

(defun eval-print-last-sexp (&optional eval-last-sexp-arg-internal)
  "Evaluate sexp before point; print value into current buffer.

Normally, this function truncates long output according to the value
of the variables `eval-expression-print-length' and
`eval-expression-print-level'.  With a prefix argument of zero,
however, there is no such truncation.  Such a prefix argument
also causes integers to be printed in several additional formats
\(octal, hexadecimal, and character).

If `eval-expression-debug-on-error' is non-nil, which is the default,
this command arranges for all errors to enter the debugger."
  (interactive "P")
  (let ((standard-output (current-buffer)))
    (terpri)
    (eval-last-sexp (or eval-last-sexp-arg-internal t))
    (terpri)))


(defun last-sexp-setup-props (beg end value alt1 alt2)
  "Set up text properties for the output of `elisp--eval-last-sexp'.
BEG and END are the start and end of the output in current-buffer.
VALUE is the Lisp value printed, ALT1 and ALT2 are strings for the
alternative printed representations that can be displayed."
  (let ((map (make-sparse-keymap)))
    (define-key map "\C-m" 'elisp-last-sexp-toggle-display)
    (define-key map [down-mouse-2] 'mouse-set-point)
    (define-key map [mouse-2] 'elisp-last-sexp-toggle-display)
    (add-text-properties
     beg end
     `(printed-value (,value ,alt1 ,alt2)
		     mouse-face highlight
		     keymap ,map
		     help-echo "RET, mouse-2: toggle abbreviated display"
		     rear-nonsticky (mouse-face keymap help-echo
						printed-value)))))


(defun elisp-last-sexp-toggle-display (&optional _arg)
  "Toggle between abbreviated and unabbreviated printed representations."
  (interactive "P")
  (save-restriction
    (widen)
    (let ((value (get-text-property (point) 'printed-value)))
      (when value
	(let ((beg (or (previous-single-property-change (min (point-max) (1+ (point)))
							'printed-value)
		       (point)))
	      (end (or (next-single-char-property-change (point) 'printed-value) (point)))
	      (standard-output (current-buffer))
	      (point (point)))
	  (delete-region beg end)
	  (insert (nth 1 value))
	  (or (= beg point)
	      (setq point (1- (point))))
	  (last-sexp-setup-props beg (point)
				 (nth 0 value)
				 (nth 2 value)
				 (nth 1 value))
	  (goto-char (min (point-max) point)))))))

(defun prin1-char (char)                ;FIXME: Move it, e.g. to simple.el.
  "Return a string representing CHAR as a character rather than as an integer.
If CHAR is not a character, return nil."
  (and (integerp char)
       (eventp char)
       (let ((c (event-basic-type char))
	     (mods (event-modifiers char))
	     string)
	 ;; Prevent ?A from turning into ?\S-a.
	 (if (and (memq 'shift mods)
		  (zerop (logand char ?\S-\^@))
		  (not (let ((case-fold-search nil))
			 (char-equal c (upcase c)))))
	     (setq c (upcase c) mods nil))
	 ;; What string are we considering using?
	 (condition-case nil
	     (setq string
		   (concat
		    "?"
		    (mapconcat
		     (lambda (modif)
		       (cond ((eq modif 'super) "\\s-")
			     (t (string ?\\ (upcase (aref (symbol-name modif) 0)) ?-))))
		     mods "")
		    (cond
		     ((memq c '(?\; ?\( ?\) ?\{ ?\} ?\[ ?\] ?\" ?\' ?\\)) (string ?\\ c))
		     ((eq c 127) "\\C-?")
		     (t
		      (string c)))))
	   (error nil))
	 ;; Verify the string reads a CHAR, not to some other character.
	 ;; If it doesn't, return nil instead.
	 (and string
	      (= (car (read-from-string string)) char)
	      string))))

(defun elisp--preceding-sexp ()
  "Return sexp before the point."
  (let ((opoint (point))
	(left-quote ?‘)
	expr)
    (save-excursion
      (with-syntax-table emacs-lisp-mode-syntax-table
	;; If this sexp appears to be enclosed in `...' or ‘...’
	;; then ignore the surrounding quotes.
	(cond ((eq (preceding-char) ?’)
	       (progn (forward-char -1) (setq opoint (point))))
	      ((or (eq (following-char) ?\')
		   (eq (preceding-char) ?\'))
	       (setq left-quote ?\`)))

        ;; When after a named character literal, skip over the entire
        ;; literal, not only its last word.
        (when (= (preceding-char) ?})
          (let ((begin (save-excursion
                         (backward-char)
                         (skip-syntax-backward "w-")
                         (backward-char 3)
                         (when (looking-at-p "\\\\N{") (point)))))
            (when begin (goto-char begin))))

	(forward-sexp -1)
	;; If we were after `?\e' (or similar case),
	;; use the whole thing, not just the `e'.
	(when (eq (preceding-char) ?\\)
	  (forward-char -1)
	  (when (eq (preceding-char) ??)
	    (forward-char -1)))

	;; Skip over hash table read syntax.
	(and (> (point) (1+ (point-min)))
	     (looking-back "#s" (- (point) 2))
	     (forward-char -2))

	;; Skip over `#N='s.
	(when (eq (preceding-char) ?=)
	  (let (labeled-p)
	    (save-excursion
	      (skip-chars-backward "0-9#=")
	      (setq labeled-p (looking-at "\\(#[0-9]+=\\)+")))
	    (when labeled-p
	      (forward-sexp -1))))

	(save-restriction
	  (if (eq (following-char) left-quote)
              ;; vladimir@cs.ualberta.ca 30-Jul-1997: Skip ` in `variable' so
              ;; that the value is returned, not the name.
	      (forward-char))
          (when (looking-at ",@?") (goto-char (match-end 0)))
	  (narrow-to-region (point-min) opoint)
	  (setq expr (read (current-buffer)))
          ;; If it's an (interactive ...) form, it's more useful to show how an
          ;; interactive call would use it.
          ;; FIXME: Is it really the right place for this?
          (when (eq (car-safe expr) 'interactive)
	    (setq expr
                  `(call-interactively
                    (lambda (&rest args) ,expr args))))
	  expr)))))
(define-obsolete-function-alias 'preceding-sexp 'elisp--preceding-sexp "25.1")

(defun elisp--eval-last-sexp (eval-last-sexp-arg-internal)
  "Evaluate sexp before point; print value in the echo area.
If EVAL-LAST-SEXP-ARG-INTERNAL is non-nil, print output into
current buffer.  If EVAL-LAST-SEXP-ARG-INTERNAL is `0', print
output with no limit on the length and level of lists, and
include additional formats for integers \(octal, hexadecimal, and
character)."
  (pcase-let*
      ((`(,insert-value ,no-truncate ,char-print-limit)
        (eval-expression-get-print-arguments eval-last-sexp-arg-internal)))
    ;; Setup the lexical environment if lexical-binding is enabled.
    (elisp--eval-last-sexp-print-value
     (eval (macroexpand-all
            (eval-sexp-add-defvars
             (elisp--eval-defun-1 (macroexpand (elisp--preceding-sexp)))))
           lexical-binding)
     (if insert-value (current-buffer) t) no-truncate char-print-limit)))

(defun elisp--eval-last-sexp-print-value
    (value output &optional no-truncate char-print-limit)
  (let* ((unabbreviated (let ((print-length nil) (print-level nil))
                          (prin1-to-string value)))
         (eval-expression-print-maximum-character char-print-limit)
         (print-length (unless no-truncate eval-expression-print-length))
         (print-level  (unless no-truncate eval-expression-print-level))
         (beg (point))
         end)
    (prog1
	(prin1 value output)
      (let ((str (and char-print-limit (eval-expression-print-format value))))
	(if str (princ str output)))
      (setq end (point))
      (when (and (bufferp output)
		 (or (not (null print-length))
		     (not (null print-level)))
		 (not (string= unabbreviated
			       (buffer-substring-no-properties beg end))))
	(last-sexp-setup-props beg end value
			       unabbreviated
			       (buffer-substring-no-properties beg end))
	))))


(defvar elisp--eval-last-sexp-fake-value (make-symbol "t"))

(defun eval-sexp-add-defvars (exp &optional pos)
  "Prepend EXP with all the `defvar's that precede it in the buffer.
POS specifies the starting position where EXP was found and defaults to point."
  (if (not lexical-binding)
      exp
    (save-excursion
      (unless pos (setq pos (point)))
      (let ((vars ()))
        (goto-char (point-min))
        (while (re-search-forward
                "(def\\(?:var\\|const\\|custom\\)[ \t\n]+\\([^; '()\n\t]+\\)"
                pos t)
          (let ((var (intern (match-string 1))))
            (unless (or (special-variable-p var)
                        (syntax-ppss-toplevel-pos
                         (save-excursion
                           (syntax-ppss (match-beginning 0)))))
              (push var vars))))
        `(progn ,@(mapcar (lambda (v) `(defvar ,v)) vars) ,exp)))))

(defun eval-last-sexp (eval-last-sexp-arg-internal)
  "Evaluate sexp before point; print value in the echo area.
Interactively, with a non `-' prefix argument, print output into
current buffer.

This commands handles `defvar', `defcustom' and `defface' the
same way that `eval-defun' does.  See the doc string of that
function for details.

Normally, this function truncates long output according to the
value of the variables `eval-expression-print-length' and
`eval-expression-print-level'.  With a prefix argument of zero,
however, there is no such truncation.
Integer values are printed in several formats (decimal, octal,
and hexadecimal).  When the prefix argument is -1 or the value
doesn't exceed `eval-expression-print-maximum-character', an
integer value is also printed as a character of that codepoint.

If `eval-expression-debug-on-error' is non-nil, which is the default,
this command arranges for all errors to enter the debugger."
  (interactive "P")
  (if (null eval-expression-debug-on-error)
      (values--store-value
       (elisp--eval-last-sexp eval-last-sexp-arg-internal))
    (let ((value
	   (let ((debug-on-error elisp--eval-last-sexp-fake-value))
	     (cons (elisp--eval-last-sexp eval-last-sexp-arg-internal)
		   debug-on-error))))
      (unless (eq (cdr value) elisp--eval-last-sexp-fake-value)
	(setq debug-on-error (cdr value)))
      (car value))))

(defun elisp--eval-defun-1 (form)
  "Treat some expressions specially.
Reset the `defvar' and `defcustom' variables to the initial value.
\(For `defcustom', use the :set function if there is one.)
Reinitialize the face according to the `defface' specification."
  ;; The code in edebug-defun should be consistent with this, but not
  ;; the same, since this gets a macroexpanded form.
  (cond ((not (listp form))
	 form)
	((and (eq (car form) 'defvar)
	      (cdr-safe (cdr-safe form))
	      (boundp (cadr form)))
	 ;; Force variable to be re-set.
	 `(progn (defvar ,(nth 1 form) nil ,@(nthcdr 3 form))
		 (setq-default ,(nth 1 form) ,(nth 2 form))))
	;; `defcustom' is now macroexpanded to
	;; `custom-declare-variable' with a quoted value arg.
	((and (eq (car form) 'custom-declare-variable)
	      (default-boundp (eval (nth 1 form) lexical-binding)))
	 ;; Force variable to be bound, using :set function if specified.
	 (let ((setfunc (memq :set form)))
	   (when setfunc
	     (setq setfunc (car-safe (cdr-safe setfunc)))
	     (or (functionp setfunc) (setq setfunc nil)))
	   (funcall (or setfunc 'set-default)
		    (eval (nth 1 form) lexical-binding)
		    ;; The second arg is an expression that evaluates to
		    ;; an expression.  The second evaluation is the one
		    ;; normally performed not by normal execution but by
		    ;; custom-initialize-set (for example), which does not
		    ;; use lexical-binding.
		    (eval (eval (nth 2 form) lexical-binding))))
	 form)
	;; `defface' is macroexpanded to `custom-declare-face'.
	((eq (car form) 'custom-declare-face)
	 ;; Reset the face.
	 (let ((face-symbol (eval (nth 1 form) lexical-binding)))
	   (remhash face-symbol face--new-frame-defaults)
	   (put face-symbol 'face-defface-spec nil)
	   (put face-symbol 'face-override-spec nil))
	 form)
	((eq (car form) 'progn)
	 (cons 'progn (mapcar #'elisp--eval-defun-1 (cdr form))))
	(t form)))

(defun elisp--eval-defun ()
  "Evaluate defun that point is in or before.
The value is displayed in the echo area.
If the current defun is actually a call to `defvar',
then reset the variable using the initial value expression
even if the variable already has some other value.
\(Normally `defvar' does not change the variable's value
if it already has a value.)

Return the result of evaluation."
  ;; FIXME: the print-length/level bindings should only be applied while
  ;; printing, not while evaluating.
  (defvar elisp--eval-defun-result)
  (let ((debug-on-error eval-expression-debug-on-error)
	(print-length eval-expression-print-length)
	(print-level eval-expression-print-level)
        elisp--eval-defun-result)
    (save-excursion
      ;; Arrange for eval-region to "read" the (possibly) altered form.
      ;; eval-region handles recording which file defines a function or
      ;; variable.
      (let ((standard-output t)
            beg end form)
        ;; Read the form from the buffer, and record where it ends.
        (save-excursion
          (end-of-defun)
          (beginning-of-defun)
          (setq beg (point))
          (setq form (funcall load-read-function (current-buffer)))
          (setq end (point)))
        ;; Alter the form if necessary.
        (let ((form (eval-sexp-add-defvars
                     (elisp--eval-defun-1
                      (macroexpand form)))))
          (eval-region beg end standard-output
                       (lambda (_ignore)
                         ;; Skipping to the end of the specified region
                         ;; will make eval-region return.
                         (goto-char end)
                         ;; This `setq' needs to be added *after* passing
                         ;; form through `elisp--eval-defun-1' since it
                         ;; would otherwise "hide" forms like `defvar's and
                         ;; thus defeat their special treatment.
                         `(setq elisp--eval-defun-result ,form))))))
    (let ((str (eval-expression-print-format elisp--eval-defun-result)))
      (if str (princ str)))
    elisp--eval-defun-result))

(defun eval-defun (edebug-it)
  "Evaluate the top-level form containing point, or after point.

If the current defun is actually a call to `defvar' or `defcustom',
evaluating it this way resets the variable using its initial value
expression (using the defcustom's :set function if there is one), even
if the variable already has some other value.  \(Normally `defvar' and
`defcustom' do not alter the value if there already is one.)  In an
analogous way, evaluating a `defface' overrides any customizations of
the face, so that it becomes defined exactly as the `defface' expression
says.

If `eval-expression-debug-on-error' is non-nil, which is the default,
this command arranges for all errors to enter the debugger.

With a prefix argument, instrument the code for Edebug.

If acting on a `defun' for FUNCTION, and the function was
instrumented, `Edebug: FUNCTION' is printed in the echo area.  If not
instrumented, just FUNCTION is printed.

If not acting on a `defun', the result of evaluation is displayed in
the echo area.  This display is controlled by the variables
`eval-expression-print-length' and `eval-expression-print-level',
which see."
  (interactive "P")
  (cond (edebug-it
	 (require 'edebug)
	 (defvar edebug-all-defs)
	 (eval-defun (not edebug-all-defs)))
	(t
	 (if (null eval-expression-debug-on-error)
	     (elisp--eval-defun)
	   (let (new-value value)
	     (let ((debug-on-error elisp--eval-last-sexp-fake-value))
	       (setq value (elisp--eval-defun))
	       (setq new-value debug-on-error))
	     (unless (eq elisp--eval-last-sexp-fake-value new-value)
	       (setq debug-on-error new-value))
	     value)))))

;;; ElDoc Support

(defvar elisp--eldoc-last-data (make-vector 3 nil)
  "Bookkeeping; elements are as follows:
  0 - contains the last symbol read from the buffer.
  1 - contains the string last displayed in the echo area for variables,
      or argument string for functions.
  2 - `function' if function args, `variable' if variable documentation.")

(defun elisp--documentation-one-liner ()
  (let* (str
         (callback (lambda (doc &rest plist)
                     (when doc
                       (setq str
                             (format "%s: %s"
                                     (propertize (prin1-to-string
                                                  (plist-get plist :thing))
                                                 'face (plist-get plist :face))
                                     doc))))))
    (or (progn (elisp-eldoc-var-docstring callback) str)
        (progn (elisp-eldoc-funcall callback) str))))

(defalias 'elisp-eldoc-documentation-function 'elisp--documentation-one-liner
  "Return Elisp documentation for the thing at point as one-line string.
This is meant as a backward compatibility aide to the \"old\"
Elisp eldoc behaviour.  Consider variable docstrings and function
signatures only, in this order.  If none applies, returns nil.
Changes to `eldoc-documentation-functions' and
`eldoc-documentation-strategy' are _not_ reflected here.  As such
it is preferable to use ElDoc's interfaces directly.")

(make-obsolete 'elisp-eldoc-documentation-function
               "use ElDoc's interfaces instead." "28.1")

(defun elisp-eldoc-funcall (callback &rest _ignored)
  "Document function call at point.
Intended for `eldoc-documentation-functions' (which see)."
  (let* ((sym-info (elisp--fnsym-in-current-sexp))
         (fn-sym (car sym-info)))
    (when fn-sym
      (funcall callback (apply #'elisp-get-fnsym-args-string sym-info)
               :thing fn-sym
               :face (if (functionp fn-sym)
                         'font-lock-function-name-face
                       'font-lock-keyword-face)))))

(defun elisp-eldoc-var-docstring (callback &rest _ignored)
  "Document variable at point.
Intended for `eldoc-documentation-functions' (which see)."
  (let* ((sym (elisp--current-symbol))
         (docstring (and sym (elisp-get-var-docstring sym))))
    (when docstring
      (funcall callback docstring
               :thing sym
               :face 'font-lock-variable-name-face))))

(defun elisp-get-fnsym-args-string (sym &optional index)
  "Return a string containing the parameter list of the function SYM.
If SYM is a subr and no arglist is obtainable from the docstring
or elsewhere, return a 1-line docstring."
  (let ((argstring
	 (cond
	  ((not (and sym (symbolp sym) (fboundp sym))) nil)
	  ((and (eq sym (aref elisp--eldoc-last-data 0))
		(eq 'function (aref elisp--eldoc-last-data 2)))
	   (aref elisp--eldoc-last-data 1))
	  (t
	   (let* ((advertised (gethash (indirect-function sym)
                                       advertised-signature-table t))
                  doc
		  (args
		   (cond
		    ((listp advertised) advertised)
		    ((setq doc (help-split-fundoc
				(condition-case nil (documentation sym t)
				  (invalid-function nil))
				sym))
		     (substitute-command-keys (car doc)))
		    (t (help-function-arglist sym)))))
             ;; Stringify, and store before highlighting, downcasing, etc.
	     (elisp--last-data-store sym (elisp-function-argstring args)
                                     'function))))))
    ;; Highlight
    (if argstring
	(elisp--highlight-function-argument
         sym argstring index))))

(defun elisp--highlight-function-argument (sym args index)
  "Highlight argument INDEX in ARGS list for function SYM."
  ;; FIXME: This should probably work on the list representation of `args'
  ;; rather than its string representation.
  ;; FIXME: This function is much too long, we need to split it up!
  (let* ((start          nil)
         (end            0)
         (argument-face  'eldoc-highlight-function-argument)
         (args-lst (mapcar (lambda (x)
                             (replace-regexp-in-string
                              "\\`[(]\\|[)]\\'" "" x))
                           (split-string args)))
         (args-lst-ak (cdr (member "&key" args-lst))))
    ;; Find the current argument in the argument string.  We need to
    ;; handle `&rest' and informal `...' properly.
    ;;
    ;; FIXME: What to do with optional arguments, like in
    ;;        (defun NAME ARGLIST [DOCSTRING] BODY...) case?
    ;;        The problem is there is no robust way to determine if
    ;;        the current argument is indeed a docstring.

    ;; When `&key' is used finding position based on `index'
    ;; would be wrong, so find the arg at point and determine
    ;; position in ARGS based on this current arg.
    (when (and args-lst-ak
               (>= index (- (length args-lst) (length args-lst-ak))))
      (let* (case-fold-search
             key-have-value
             (sym-name (symbol-name sym))
             (cur-w (current-word t))
             (limit (save-excursion
                      (when (re-search-backward sym-name nil t)
                        (match-end 0))))
             (cur-a (if (and cur-w (string-match ":\\([^ ()]*\\)" cur-w))
                        (substring cur-w 1)
                      (save-excursion
                        (let (split)
                          (when (re-search-backward ":\\([^ ()\n]*\\)" limit t)
                            (setq split (split-string (match-string 1) " " t))
                            (prog1 (car split)
                              (when (cdr split)
                                (setq key-have-value t))))))))
             ;; If `cur-a' is not one of `args-lst-ak'
             ;; assume user is entering an unknown key
             ;; referenced in last position in signature.
             (other-key-arg (and (stringp cur-a)
                                 args-lst-ak
                                 (not (member (upcase cur-a) args-lst-ak))
                                 (upcase (car (last args-lst-ak))))))
        (unless (or (null cur-w) (string= cur-w sym-name))
          ;; The last keyword have already a value
          ;; i.e :foo a b and cursor is at b.
          ;; If signature have also `&rest'
          ;; (assume it is after the `&key' section)
          ;; go to the arg after `&rest'.
          (if (and key-have-value
                   (save-excursion
                     (not (re-search-forward ":.*" (point-at-eol) t)))
                   (string-match "&rest \\([^ ()]*\\)" args))
              (setq index nil ; Skip next block based on positional args.
                    start (match-beginning 1)
                    end   (match-end 1))
            ;; If `cur-a' is nil probably cursor is on a positional arg
            ;; before `&key', in this case, exit this block and determine
            ;; position with `index'.
            (when (and cur-a     ; A keyword arg (dot removed) or nil.
                       (or (string-match
                            (concat "\\_<" (upcase cur-a) "\\_>") args)
                           (string-match
                            (concat "\\_<" other-key-arg "\\_>") args)))
              (setq index nil ; Skip next block based on positional args.
                    start (match-beginning 0)
                    end   (match-end 0)))))))
    ;; Handle now positional arguments.
    (while (and index (>= index 1))
      (if (string-match "[^ ()]+" args end)
	  (progn
	    (setq start (match-beginning 0)
		  end   (match-end 0))
	    (let ((argument (match-string 0 args)))
	      (cond ((string= argument "&rest")
		     ;; All the rest arguments are the same.
		     (setq index 1))
		    ((string= argument "&optional"))         ; Skip.
                    ((string= argument "&allow-other-keys")) ; Skip.
                    ;; Back to index 0 in ARG1 ARG2 ARG2 ARG3 etc...
                    ;; like in `setq'.
		    ((or (and (string-match-p "\\.\\.\\.\\'" argument)
                              (string= argument (car (last args-lst))))
                         (and (string-match-p "\\.\\.\\.\\'"
                                              (substring args 1 (1- (length args))))
                              (= (length (remove "..." args-lst)) 2)
                              (> index 1) (eq (logand index 1) 1)))
                     (setq index 0))
		    (t
		     (setq index (1- index))))))
	(setq end           (length args)
	      start         (1- end)
	      argument-face 'font-lock-warning-face
	      index         0)))
    (let ((doc args))
      (when start
	(setq doc (copy-sequence args))
	(add-text-properties start end (list 'face argument-face) doc))
      doc)))

;; Return a string containing a brief (one-line) documentation string for
;; the variable.
(defun elisp-get-var-docstring (sym)
  (cond ((not sym) nil)
        ((and (eq sym (aref elisp--eldoc-last-data 0))
              (eq 'variable (aref elisp--eldoc-last-data 2)))
         (aref elisp--eldoc-last-data 1))
        (t
         (let ((doc (documentation-property sym 'variable-documentation t)))
           (when doc
             (let ((doc (elisp--docstring-first-line doc)))
               (elisp--last-data-store sym doc 'variable)))))))

(defun elisp--last-data-store (symbol doc type)
  (aset elisp--eldoc-last-data 0 symbol)
  (aset elisp--eldoc-last-data 1 doc)
  (aset elisp--eldoc-last-data 2 type)
  doc)

;; Note that any leading `*' in the docstring (which indicates the variable
;; is a user option) is removed.
(defun elisp--docstring-first-line (doc)
  (and (stringp doc)
       (substitute-command-keys
        (save-match-data
	  ;; Don't use "^" in the regexp below since it may match
	  ;; anywhere in the doc-string.
	  (let ((start (if (string-match "\\`\\*" doc) (match-end 0) 0)))
            (cond ((string-match "\n" doc)
                   (substring doc start (match-beginning 0)))
                  ((zerop start) doc)
                  (t (substring doc start))))))))

;; Return a list of current function name and argument index.
(defun elisp--fnsym-in-current-sexp ()
  (save-excursion
    (unless (nth 8 (syntax-ppss))
      (let ((argument-index (1- (elisp--beginning-of-sexp))))
        ;; If we are at the beginning of function name, this will be -1.
        (when (< argument-index 0)
          (setq argument-index 0))
        (list (elisp--current-symbol) argument-index)))))

;; Move to the beginning of current sexp.  Return the number of nested
;; sexp the point was over or after.
(defun elisp--beginning-of-sexp ()
  (let ((parse-sexp-ignore-comments t)
	(num-skipped-sexps 0))
    (condition-case _
	(progn
	  ;; First account for the case the point is directly over a
	  ;; beginning of a nested sexp.
	  (condition-case _
	      (let ((p (point)))
		(forward-sexp -1)
		(forward-sexp 1)
		(when (< (point) p)
		  (setq num-skipped-sexps 1)))
	    (error))
	  (while
	      (let ((p (point)))
		(forward-sexp -1)
		(when (< (point) p)
		  (setq num-skipped-sexps (1+ num-skipped-sexps))))))
      (error))
    num-skipped-sexps))

;; returns nil unless current word is an interned symbol.
(defun elisp--current-symbol ()
  (let ((c (char-after (point))))
    (and c
         (memq (char-syntax c) '(?w ?_))
         (intern-soft (current-word)))))

(defun elisp-function-argstring (arglist)
  "Return ARGLIST as a string enclosed by ().
ARGLIST is either a string, or a list of strings or symbols."
  (let ((str (cond ((stringp arglist) arglist)
                   ((not (listp arglist)) nil)
                   (t (substitute-command-keys
                       (help--make-usage-docstring 'toto arglist))))))
    (if (and str (string-match "\\`([^ )]+ ?" str))
        (replace-match "(" t t str)
      str)))

;;; Flymake support

;; Don't require checkdoc, but forward declare these checkdoc special
;; variables. Autoloading them on `checkdoc-current-buffer' is too
;; late, they won't be bound dynamically.
(defvar checkdoc-create-error-function)
(defvar checkdoc-autofix-flag)
(defvar checkdoc-generate-compile-warnings-flag)
(defvar checkdoc-diagnostic-buffer)

;;;###autoload
(defun elisp-flymake-checkdoc (report-fn &rest _args)
  "A Flymake backend for `checkdoc'.
Calls REPORT-FN directly."
  (let (collected)
    (let* ((checkdoc-create-error-function
            (lambda (text start end &optional unfixable)
              (push (list text start end unfixable) collected)
              nil))
           (checkdoc-autofix-flag nil)
           (checkdoc-generate-compile-warnings-flag nil)
           (checkdoc-diagnostic-buffer
            (generate-new-buffer " *checkdoc-temp*")))
      (unwind-protect
          (save-excursion
            ;; checkdoc-current-buffer can error if there are
            ;; unbalanced parens, for example, but this shouldn't
            ;; disable the backend (bug#29176).
            (ignore-errors
              (checkdoc-current-buffer t)))
        (kill-buffer checkdoc-diagnostic-buffer)))
    (funcall report-fn
             (cl-loop for (text start end _unfixable) in
                      collected
                      collect
                      (flymake-make-diagnostic
                       (current-buffer)
                       (or start 1) (or end (1+ (or start 1)))
                       :note text)))
    collected))

(defun elisp-flymake--byte-compile-done (report-fn
                                         source-buffer
                                         output-buffer)
  (with-current-buffer
      source-buffer
    (save-excursion
      (save-restriction
        (widen)
        (funcall
         report-fn
         (cl-loop with data =
                  (with-current-buffer output-buffer
                    (goto-char (point-min))
                    (search-forward ":elisp-flymake-output-start")
                    (read (point-marker)))
                  for (string pos _fill level) in data
                  do (goto-char pos)
                  for beg = (if (< (point) (point-max))
                                (point)
                              (line-beginning-position))
                  for end = (min
                             (line-end-position)
                             (or (cdr
                                  (bounds-of-thing-at-point 'sexp))
                                 (point-max)))
                  collect (flymake-make-diagnostic
                           (current-buffer)
                           (if (= beg end) (1- beg) beg)
                           end
                           level
                           string)))))))

(defvar-local elisp-flymake--byte-compile-process nil
  "Buffer-local process started for byte-compiling the buffer.")

(defvar elisp-flymake-byte-compile-load-path (list "./")
  "Like `load-path' but used by `elisp-flymake-byte-compile'.
The default value contains just \"./\" which includes the default
directory of the buffer being compiled, and nothing else.")

(put 'elisp-flymake-byte-compile-load-path 'safe-local-variable
     (lambda (x) (and (listp x) (catch 'tag
                                  (dolist (path x t) (unless (stringp path)
                                                       (throw 'tag nil)))))))

;;;###autoload
(defun elisp-flymake-byte-compile (report-fn &rest _args)
  "A Flymake backend for elisp byte compilation.
Spawn an Emacs process that byte-compiles a file representing the
current buffer state and calls REPORT-FN when done."
  (when elisp-flymake--byte-compile-process
    (when (process-live-p elisp-flymake--byte-compile-process)
      (kill-process elisp-flymake--byte-compile-process)))
  (let ((temp-file (make-temp-file "elisp-flymake-byte-compile"))
        (source-buffer (current-buffer)))
    (save-restriction
      (widen)
      (write-region (point-min) (point-max) temp-file nil 'nomessage))
    (let* ((output-buffer (generate-new-buffer " *elisp-flymake-byte-compile*")))
      (setq
       elisp-flymake--byte-compile-process
       (make-process
        :name "elisp-flymake-byte-compile"
        :buffer output-buffer
        :command `(,(expand-file-name invocation-name invocation-directory)
                   "-Q"
                   "--batch"
                   ;; "--eval" "(setq load-prefer-newer t)" ; for testing
                   ,@(mapcan (lambda (path) (list "-L" path))
                             elisp-flymake-byte-compile-load-path)
                   "-f" "elisp-flymake--batch-compile-for-flymake"
                   ,temp-file)
        :connection-type 'pipe
        :sentinel
        (lambda (proc _event)
          (when (eq (process-status proc) 'exit)
            (unwind-protect
                (cond
                 ((not (and (buffer-live-p source-buffer)
                            (eq proc (with-current-buffer source-buffer
                                       elisp-flymake--byte-compile-process))))
                  (flymake-log :warning
                               "byte-compile process %s obsolete" proc))
                 ((zerop (process-exit-status proc))
                  (elisp-flymake--byte-compile-done report-fn
                                                    source-buffer
                                                    output-buffer))
                 (t
                  (funcall report-fn
                           :panic
                           :explanation
                           (format "byte-compile process %s died" proc))))
              (ignore-errors (delete-file temp-file))
              (kill-buffer output-buffer))))
        :stderr " *stderr of elisp-flymake-byte-compile*"
        :noquery t)))))

(defun elisp-flymake--batch-compile-for-flymake (&optional file)
  "Helper for `elisp-flymake-byte-compile'.
Runs in a batch-mode Emacs.  Interactively use variable
`buffer-file-name' for FILE."
  (interactive (list buffer-file-name))
  (let* ((file (or file
                   (car command-line-args-left)))
         (byte-compile-log-buffer
          (generate-new-buffer " *dummy-byte-compile-log-buffer*"))
         (byte-compile-dest-file-function #'ignore)
         (collected)
         (byte-compile-log-warning-function
          (lambda (string &optional position fill level)
            (push (list string position fill level)
                  collected)
            t)))
    (unwind-protect
        (byte-compile-file file)
      (ignore-errors
        (kill-buffer byte-compile-log-buffer)))
    (prin1 :elisp-flymake-output-start)
    (terpri)
    (pp collected)))

(provide 'elisp-mode)
;;; elisp-mode.el ends here