;;; flymake.el --- A universal on-the-fly syntax checker  -*- lexical-binding: t; -*-

;; Copyright (C) 2003-2018 Free Software Foundation, Inc.

;; Author:  Pavel Kobyakov <pk_at_work@yahoo.com>
;; Maintainer: João Távora <joaotavora@gmail.com>
;; Version: 1.0
;; Keywords: c languages tools

;; 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:
;;
;; Flymake is a minor Emacs mode performing on-the-fly syntax checks.
;;
;; Flymake collects diagnostic information for multiple sources,
;; called backends, and visually annotates the relevant portions in
;; the buffer.
;;
;; This file contains the UI for displaying and interacting with the
;; results produced by these backends, as well as entry points for
;; backends to hook on to.
;;
;; The main interactive entry point is the `flymake-mode' minor mode,
;; which periodically and automatically initiates checks as the user
;; is editing the buffer.  The variables `flymake-no-changes-timeout',
;; `flymake-start-syntax-check-on-newline' and
;; `flymake-start-on-flymake-mode' give finer control over the events
;; triggering a check, as does the interactive command
;; `flymake-start', which immediately starts a check.
;;
;; Shortly after each check, a summary of collected diagnostics should
;; appear in the mode-line.  If it doesn't, there might not be a
;; suitable Flymake backend for the current buffer's major mode, in
;; which case Flymake will indicate this in the mode-line.  The
;; indicator will be `!' (exclamation mark), if all the configured
;; backends errored (or decided to disable themselves) and `?'
;; (question mark) if no backends were even configured.
;;
;; For programmers interested in writing a new Flymake backend, the
;; docstring of `flymake-diagnostic-functions', the Flymake manual,
;; and the code of existing backends are probably a good starting
;; point.
;;
;; The user wishing to customize the appearance of error types should
;; set properties on the symbols associated with each diagnostic type.
;; The standard diagnostic symbols are `:error', `:warning' and
;; `:note' (though a specific backend may define and use more).  The
;; following properties can be set:
;;
;; * `flymake-bitmap', an image displayed in the fringe according to
;; `flymake-fringe-indicator-position'.  The value actually follows
;; the syntax of `flymake-error-bitmap' (which see).  It is overridden
;; by any `before-string' overlay property.
;;
;; * `flymake-severity', a non-negative integer specifying the
;; diagnostic's severity.  The higher, the more serious.  If the
;; overlay property `priority' is not specified, `severity' is used to
;; set it and help sort overlapping overlays.
;;
;; * `flymake-overlay-control', an alist ((OVPROP . VALUE) ...) of
;; further properties used to affect the appearance of Flymake
;; annotations.  With the exception of `category' and `evaporate',
;; these properties are applied directly to the created overlay.  See
;; Info Node `(elisp)Overlay Properties'.
;;
;; * `flymake-category', a symbol whose property list is considered a
;; default for missing values of any other properties.  This is useful
;; to backend authors when creating new diagnostic types that differ
;; from an existing type by only a few properties.  The category
;; symbols `flymake-error', `flymake-warning' and `flymake-note' make
;; good candidates for values of this property.
;;
;; For instance, to omit the fringe bitmap displayed for the standard
;; `:note' type, set its `flymake-bitmap' property to nil:
;;
;;   (put :note 'flymake-bitmap nil)
;;
;; To change the face for `:note' type, add a `face' entry to its
;; `flymake-overlay-control' property.
;;
;;   (push '(face . highlight) (get :note 'flymake-overlay-control))
;;
;; If you push another alist entry in front, it overrides the previous
;; one.  So this effectively removes the face from `:note'
;; diagnostics.
;;
;;   (push '(face . nil) (get :note 'flymake-overlay-control))
;;
;; To erase customizations and go back to the original look for
;; `:note' types:
;;
;;   (cl-remf (symbol-plist :note) 'flymake-overlay-control)
;;   (cl-remf (symbol-plist :note) 'flymake-bitmap)
;;
;;; Code:

(require 'cl-lib)
(require 'thingatpt) ; end-of-thing
(require 'warnings) ; warning-numeric-level, display-warning
(require 'compile) ; for some faces
;; We need the next require to avoid compiler warnings and run-time
;; errors about mouse-wheel-up/down-event in builds --without-x, where
;; mwheel is not preloaded.
(require 'mwheel)
;; when-let*, if-let*, hash-table-keys, hash-table-values:
(eval-when-compile (require 'subr-x))

(defgroup flymake nil
  "Universal on-the-fly syntax checker."
  :version "23.1"
  :link '(custom-manual "(flymake) Top")
  :group 'tools)

(defcustom flymake-error-bitmap '(flymake-double-exclamation-mark
                                  compilation-error)
  "Bitmap (a symbol) used in the fringe for indicating errors.
The value may also be a list of two elements where the second
element specifies the face for the bitmap.  For possible bitmap
symbols, see `fringe-bitmaps'.  See also `flymake-warning-bitmap'.

The option `flymake-fringe-indicator-position' controls how and where
this is used."
  :version "24.3"
  :type '(choice (symbol :tag "Bitmap")
                 (list :tag "Bitmap and face"
                       (symbol :tag "Bitmap")
                       (face :tag "Face"))))

(defcustom flymake-warning-bitmap '(exclamation-mark compilation-warning)
  "Bitmap (a symbol) used in the fringe for indicating warnings.
The value may also be a list of two elements where the second
element specifies the face for the bitmap.  For possible bitmap
symbols, see `fringe-bitmaps'.  See also `flymake-error-bitmap'.

The option `flymake-fringe-indicator-position' controls how and where
this is used."
  :version "24.3"
  :type '(choice (symbol :tag "Bitmap")
                 (list :tag "Bitmap and face"
                       (symbol :tag "Bitmap")
                       (face :tag "Face"))))

(defcustom flymake-note-bitmap '(exclamation-mark compilation-info)
  "Bitmap (a symbol) used in the fringe for indicating info notes.
The value may also be a list of two elements where the second
element specifies the face for the bitmap.  For possible bitmap
symbols, see `fringe-bitmaps'.  See also `flymake-error-bitmap'.

The option `flymake-fringe-indicator-position' controls how and where
this is used."
  :version "26.1"
  :type '(choice (symbol :tag "Bitmap")
                 (list :tag "Bitmap and face"
                       (symbol :tag "Bitmap")
                       (face :tag "Face"))))

(defcustom flymake-fringe-indicator-position 'left-fringe
  "The position to put Flymake fringe indicator.
The value can be nil (do not use indicators), `left-fringe' or `right-fringe'.
See `flymake-error-bitmap' and `flymake-warning-bitmap'."
  :version "24.3"
  :type '(choice (const left-fringe)
		 (const right-fringe)
		 (const :tag "No fringe indicators" nil)))

(defcustom flymake-start-syntax-check-on-newline t
  "Start syntax check if newline char was added/removed from the buffer."
  :type 'boolean)

(defcustom flymake-no-changes-timeout 0.5
  "Time to wait after last change before automatically checking buffer.
If nil, never start checking buffer automatically like this."
  :type 'number)

(defcustom flymake-gui-warnings-enabled t
  "Enables/disables GUI warnings."
  :type 'boolean)
(make-obsolete-variable 'flymake-gui-warnings-enabled
			"it no longer has any effect." "26.1")

(define-obsolete-variable-alias 'flymake-start-syntax-check-on-find-file
  'flymake-start-on-flymake-mode "26.1")

(defcustom flymake-start-on-flymake-mode t
  "If non-nil, start syntax check when `flymake-mode' is enabled.
Specifically, start it when the buffer is actually displayed."
  :version "26.1"
  :type 'boolean)

(defcustom flymake-start-on-save-buffer t
  "If non-nil start syntax check when a buffer is saved.
Specifically, start it when the saved buffer is actually displayed."
  :version "27.1"
  :type 'boolean)

(defcustom flymake-log-level -1
  "Obsolete and ignored variable."
  :type 'integer)
(make-obsolete-variable 'flymake-log-level
			"it is superseded by `warning-minimum-log-level.'"
                        "26.1")

(defcustom flymake-wrap-around t
  "If non-nil, moving to errors wraps around buffer boundaries."
  :version "26.1"
  :type 'boolean)

(when (fboundp 'define-fringe-bitmap)
  (define-fringe-bitmap 'flymake-double-exclamation-mark
    (vector #b00000000
            #b00000000
            #b00000000
            #b00000000
            #b01100110
            #b01100110
            #b01100110
            #b01100110
            #b01100110
            #b01100110
            #b01100110
            #b01100110
            #b00000000
            #b01100110
            #b00000000
            #b00000000
            #b00000000)))

(defvar-local flymake-timer nil
  "Timer for starting syntax check.")

(defvar-local flymake-check-start-time nil
  "Time at which syntax check was started.")

(defun flymake--log-1 (level sublog msg &rest args)
  "Do actual work for `flymake-log'."
  (let (;; never popup the log buffer
        (warning-minimum-level :emergency)
        (warning-type-format
         (format " [%s %s]"
                 (or sublog 'flymake)
                 (current-buffer))))
    (display-warning (list 'flymake sublog)
                     (apply #'format-message msg args)
                     (if (numberp level)
                         (or (nth level
                                  '(:emergency :error :warning :debug :debug) )
                             :error)
                       level)
                     "*Flymake log*")))

(defun flymake-switch-to-log-buffer ()
  "Go to the *Flymake log* buffer."
  (interactive)
  (switch-to-buffer "*Flymake log*"))

;;;###autoload
(defmacro flymake-log (level msg &rest args)
  "Log, at level LEVEL, the message MSG formatted with ARGS.
LEVEL is passed to `display-warning', which is used to display
the warning.  If this form is included in a byte-compiled file,
the generated warning contains an indication of the file that
generated it."
  (let* ((compile-file (and (boundp 'byte-compile-current-file)
                            (symbol-value 'byte-compile-current-file)))
         (sublog (if (and
                      compile-file
                      (not load-file-name))
                     (intern
                      (file-name-nondirectory
                       (file-name-sans-extension compile-file))))))
    `(flymake--log-1 ,level ',sublog ,msg ,@args)))

(defun flymake-error (text &rest args)
  "Format TEXT with ARGS and signal an error for Flymake."
  (let ((msg (apply #'format-message text args)))
    (flymake-log :error msg)
    (error (concat "[Flymake] " msg))))

(cl-defstruct (flymake--diag
               (:constructor flymake--diag-make))
  buffer beg end type text backend data overlay)

;;;###autoload
(defun flymake-make-diagnostic (buffer
                                beg
                                end
                                type
                                text
                                &optional data)
  "Make a Flymake diagnostic for BUFFER's region from BEG to END.
TYPE is a key to symbol and TEXT is a description of the problem
detected in this region.  DATA is any object that the caller
wishes to attach to the created diagnostic for later retrieval."
  (flymake--diag-make :buffer buffer :beg beg :end end
                      :type type :text text :data data))

;;;###autoload
(defun flymake-diagnostics (&optional beg end)
  "Get Flymake diagnostics in region determined by BEG and END.

If neither BEG or END is supplied, use the whole buffer,
otherwise if BEG is non-nil and END is nil, consider only
diagnostics at BEG."
  (mapcar (lambda (ov) (overlay-get ov 'flymake-diagnostic))
          (flymake--overlays :beg beg :end end)))

(defmacro flymake--diag-accessor (public internal thing)
  "Make PUBLIC an alias for INTERNAL, add doc using THING."
  `(defsubst ,public (diag)
     ,(format "Get Flymake diagnostic DIAG's %s." (symbol-name thing))
     (,internal diag)))

(flymake--diag-accessor flymake-diagnostic-buffer flymake--diag-buffer buffer)
(flymake--diag-accessor flymake-diagnostic-text flymake--diag-text text)
(flymake--diag-accessor flymake-diagnostic-type flymake--diag-type type)
(flymake--diag-accessor flymake-diagnostic-beg flymake--diag-beg beg)
(flymake--diag-accessor flymake-diagnostic-end flymake--diag-end end)
(flymake--diag-accessor flymake-diagnostic-backend flymake--diag-backend backend)
(flymake--diag-accessor flymake-diagnostic-data flymake--diag-data backend)

(cl-defun flymake--overlays (&key beg end filter compare key)
  "Get flymake-related overlays.
If BEG is non-nil and END is nil, consider only `overlays-at'
BEG. Otherwise consider `overlays-in' the region comprised by BEG
and END, defaulting to the whole buffer.  Remove all that do not
verify FILTER, a function, and sort them by COMPARE (using KEY)."
  (save-restriction
    (widen)
    (let ((ovs (cl-remove-if-not
                (lambda (ov)
                  (and (overlay-get ov 'flymake-diagnostic)
                       (or (not filter)
                           (funcall filter ov))))
                (if (and beg (null end))
                    (overlays-at beg t)
                  (overlays-in (or beg (point-min))
                               (or end (point-max)))))))
      (if compare
          (cl-sort ovs compare :key (or key
                                        #'identity))
        ovs))))

(defface flymake-error
  '((((supports :underline (:style wave)))
     :underline (:style wave :color "Red1"))
    (t
     :inherit error))
  "Face used for marking error regions."
  :version "24.4")

(defface flymake-warning
  '((((supports :underline (:style wave)))
     :underline (:style wave :color "deep sky blue"))
    (t
     :inherit warning))
  "Face used for marking warning regions."
  :version "24.4")

(defface flymake-note
  '((((supports :underline (:style wave)))
     :underline (:style wave :color "yellow green"))
    (t
     :inherit warning))
  "Face used for marking note regions."
  :version "26.1")

(define-obsolete-face-alias 'flymake-warnline 'flymake-warning "26.1")
(define-obsolete-face-alias 'flymake-errline 'flymake-error "26.1")

;;;###autoload
(defun flymake-diag-region (buffer line &optional col)
  "Compute BUFFER's region (BEG . END) corresponding to LINE and COL.
If COL is nil, return a region just for LINE.  Return nil if the
region is invalid."
  (condition-case-unless-debug _err
      (with-current-buffer buffer
        (let ((line (min (max line 1)
                         (line-number-at-pos (point-max) 'absolute))))
          (save-excursion
            (goto-char (point-min))
            (forward-line (1- line))
            (cl-flet ((fallback-bol
                       ()
                       (back-to-indentation)
                       (if (eobp)
                           (line-beginning-position 0)
                         (point)))
                      (fallback-eol
                       (beg)
                       (progn
                         (end-of-line)
                         (skip-chars-backward " \t\f\t\n" beg)
                         (if (eq (point) beg)
                             (line-beginning-position 2)
                           (point)))))
              (if (and col (cl-plusp col))
                  (let* ((beg (progn (forward-char (1- col))
                                     (point)))
                         (sexp-end (ignore-errors (end-of-thing 'sexp)))
                         (end (or (and sexp-end
                                       (not (= sexp-end beg))
                                       sexp-end)
                                  (and (< (goto-char (1+ beg)) (point-max))
                                       (point)))))
                    (if end
                        (cons beg end)
                      (cons (setq beg (fallback-bol))
                            (fallback-eol beg))))
                (let* ((beg (fallback-bol))
                       (end (fallback-eol beg)))
                  (cons beg end)))))))
    (error (flymake-log :warning "Invalid region line=%s col=%s" line col)
           nil)))

(defvar flymake-diagnostic-functions nil
  "Special hook of Flymake backends that check a buffer.

The functions in this hook diagnose problems in a buffer's
contents and provide information to the Flymake user interface
about where and how to annotate problems diagnosed in a buffer.

Each backend function must be prepared to accept an arbitrary
number of arguments:

* the first argument is always REPORT-FN, a callback function
  detailed below;

* the remaining arguments are keyword-value pairs in the
  form (:KEY VALUE :KEY2 VALUE2...).

Currently, Flymake may provide these keyword-value pairs:

* `:recent-changes', a list of recent changes since the last time
  the backend function was called for the buffer.  An empty list
  indicates that no changes have been reocrded.  If it is the
  first time that this backend function is called for this
  activation of `flymake-mode', then this argument isn't provided
  at all (i.e. it's not merely nil).

  Each element is in the form (BEG END TEXT) where BEG and END
  are buffer positions, and TEXT is a string containing the text
  contained between those positions (if any) after the change was
  performed.

* `:changes-start' and `:changes-end', the minimum and maximum
  buffer positions touched by the recent changes.  These are only
  provided if `:recent-changes' is also provided.

Whenever Flymake or the user decides to re-check the buffer,
backend functions are called as detailed above and are expected
to initiate this check, but aren't required to complete it before
exiting: if the computation involved is expensive, especially for
large buffers, that task can be scheduled for the future using
asynchronous processes or other asynchronous mechanisms.

In any case, backend functions are expected to return quickly or
signal an error, in which case the backend is disabled.  Flymake
will not try disabled backends again for any future checks of
this buffer.  To reset the list of disabled backends, turn
`flymake-mode' off and on again, or interactively call
`flymake-start' with a prefix argument.

If the function returns, Flymake considers the backend to be
\"running\". If it has not done so already, the backend is
expected to call the function REPORT-FN with a single argument
REPORT-ACTION also followed by an optional list of keyword-value
pairs in the form (:REPORT-KEY VALUE :REPORT-KEY2 VALUE2...).

Currently accepted values for REPORT-ACTION are:

* A (possibly empty) list of diagnostic objects created with
  `flymake-make-diagnostic', causing Flymake to delete all
  previous diagnostic annotations in the buffer and create new
  ones from this list.

  A backend may call REPORT-FN repeatedly in this manner, but
  only until Flymake considers that the most recently requested
  buffer check is now obsolete because, say, buffer contents have
  changed in the meantime. The backend is only given notice of
  this via a renewed call to the backend function. Thus, to
  prevent making obsolete reports and wasting resources, backend
  functions should first cancel any ongoing processing from
  previous calls.

* The symbol `:panic', signaling that the backend has encountered
  an exceptional situation and should be disabled.

Currently accepted REPORT-KEY arguments are:

* `:explanation' value should give user-readable details of
  the situation encountered, if any.

* `:force': value should be a boolean suggesting that Flymake
  consider the report even if it was somehow unexpected.

* `:region': a cons (BEG . END) of buffer positions indicating
  that the report applies to that region only.  Specifically,
  this means that Flymake will only delete diagnostic annotations
  of past reports if they intersect the region by at least one
  character.")

(put 'flymake-diagnostic-functions 'safe-local-variable #'null)

(put :error 'flymake-category 'flymake-error)
(put :warning 'flymake-category 'flymake-warning)
(put :note 'flymake-category 'flymake-note)

(defvar flymake-diagnostic-types-alist `() "")
(make-obsolete-variable
 'flymake-diagnostic-types-alist
 "Set properties on the diagnostic symbols instead. See Info
Node `(Flymake)Flymake error types'"
 "27.1")

(put 'flymake-error 'face 'flymake-error)
(put 'flymake-error 'flymake-bitmap 'flymake-error-bitmap)
(put 'flymake-error 'severity (warning-numeric-level :error))
(put 'flymake-error 'mode-line-face 'compilation-error)

(put 'flymake-warning 'face 'flymake-warning)
(put 'flymake-warning 'flymake-bitmap 'flymake-warning-bitmap)
(put 'flymake-warning 'severity (warning-numeric-level :warning))
(put 'flymake-warning 'mode-line-face 'compilation-warning)

(put 'flymake-note 'face 'flymake-note)
(put 'flymake-note 'flymake-bitmap 'flymake-note-bitmap)
(put 'flymake-note 'severity (warning-numeric-level :debug))
(put 'flymake-note 'mode-line-face 'compilation-info)

(defun flymake--lookup-type-property (type prop &optional default)
  "Look up PROP for diagnostic TYPE.
If TYPE doesn't declare PROP in its plist or in the symbol of its
associated `flymake-category' return DEFAULT."
  ;; This function also consults `flymake-diagnostic-types-alist' for
  ;; backward compatibility.
  ;;
  (if (plist-member (symbol-plist type) prop)
      ;; allow nil values to survive
      (get type prop)
    (let (alist)
      (or
       (alist-get
        prop (setq
              alist
              (alist-get type flymake-diagnostic-types-alist)))
       (when-let* ((cat (or
                         (get type 'flymake-category)
                         (alist-get 'flymake-category alist)))
                   (plist (and (symbolp cat)
                               (symbol-plist cat)))
                   (cat-probe (plist-member plist prop)))
         (cadr cat-probe))
       default))))

(defun flymake--severity (type)
  "Get the severity for diagnostic TYPE."
  (flymake--lookup-type-property type 'severity
                                 (warning-numeric-level :error)))

(defun flymake--fringe-overlay-spec (bitmap &optional recursed)
  (if (and (symbolp bitmap)
           (boundp bitmap)
           (not recursed))
      (flymake--fringe-overlay-spec
       (symbol-value bitmap) t)
    (and flymake-fringe-indicator-position
         bitmap
         (propertize "!" 'display
                     (cons flymake-fringe-indicator-position
                           (if (listp bitmap)
                               bitmap
                             (list bitmap)))))))

(defun flymake--highlight-line (diagnostic)
  "Highlight buffer with info in DIGNOSTIC."
  (when-let* ((type (flymake--diag-type diagnostic))
              (ov (make-overlay
                   (flymake--diag-beg diagnostic)
                   (flymake--diag-end diagnostic))))
    ;; First set `category' in the overlay
    ;;
    (overlay-put ov 'category
                 (flymake--lookup-type-property type 'flymake-category))
    ;; Now "paint" the overlay with all the other non-category
    ;; properties.
    (cl-loop
     for (ov-prop . value) in
     (append (reverse ; ensure ealier props override later ones
              (flymake--lookup-type-property type 'flymake-overlay-control))
             (alist-get type flymake-diagnostic-types-alist))
     do (overlay-put ov ov-prop value))
    ;; Now ensure some essential defaults are set
    ;;
    (cl-flet ((default-maybe
                (prop value)
                (unless (plist-member (overlay-properties ov) prop)
                  (overlay-put ov prop (flymake--lookup-type-property
                                        type prop value)))))
      (default-maybe 'face 'flymake-error)
      (default-maybe 'before-string
        (flymake--fringe-overlay-spec
         (flymake--lookup-type-property
          type
          'flymake-bitmap
          (alist-get 'bitmap (alist-get type ; backward compat
                                        flymake-diagnostic-types-alist)))))
      (default-maybe 'help-echo
        (lambda (window _ov pos)
          (with-selected-window window
            (mapconcat
             #'flymake--diag-text
             (flymake-diagnostics pos)
             "\n"))))
      (default-maybe 'severity (warning-numeric-level :error))
      (default-maybe 'priority (+ 100 (overlay-get ov 'severity))))
    ;; Some properties can't be overridden.
    ;;
    (overlay-put ov 'evaporate t)
    (overlay-put ov 'flymake-diagnostic diagnostic)
    ov))

;; Nothing in Flymake uses this at all any more, so this is just for
;; third-party compatibility.
(define-obsolete-function-alias 'flymake-display-warning 'message-box "26.1")

(defvar-local flymake--backend-state nil
  "Buffer-local hash table of a Flymake backend's state.
The keys to this hash table are functions as found in
`flymake-diagnostic-functions'. The values are structures
of the type `flymake--backend-state', with these slots:

`running', a symbol to keep track of a backend's replies via its
REPORT-FN argument. A backend is running if this key is
present. If nil, Flymake isn't expecting any replies from the
backend.

`diags', a (possibly empty) list of recent diagnostic objects
created by the backend with `flymake-make-diagnostic'.

`reported-p', a boolean indicating if the backend has replied
since it last was contacted.

`disabled', a string with the explanation for a previous
exceptional situation reported by the backend, nil if the
backend is operating normally.")

(cl-defstruct (flymake--backend-state
               (:constructor flymake--make-backend-state))
  running reported-p disabled diags)

(defmacro flymake--with-backend-state (backend state-var &rest body)
  "Bind BACKEND's STATE-VAR to its state, run BODY."
  (declare (indent 2) (debug (sexp sexp &rest form)))
  (let ((b (make-symbol "b")))
    `(let* ((,b ,backend)
            (,state-var
             (or (gethash ,b flymake--backend-state)
                 (puthash ,b (flymake--make-backend-state)
                          flymake--backend-state))))
       ,@body)))

(defun flymake-is-running ()
  "Tell if Flymake has running backends in this buffer"
  (flymake-running-backends))

(cl-defun flymake--handle-report (backend token report-action
                                          &key explanation force region
                                          &allow-other-keys)
  "Handle reports from BACKEND identified by TOKEN.
BACKEND, REPORT-ACTION and EXPLANATION, and FORCE conform to the
calling convention described in
`flymake-diagnostic-functions' (which see).  Optional FORCE says
to handle a report even if TOKEN was not expected.  REGION is
a (BEG . END) pair of buffer positions indicating that this
report applies to that region."
  (let* ((state (gethash backend flymake--backend-state))
         (first-report (not (flymake--backend-state-reported-p state))))
    (setf (flymake--backend-state-reported-p state) t)
    (let (expected-token
          new-diags)
      (cond
       ((null state)
        (flymake-error
         "Unexpected report from unknown backend %s" backend))
       ((flymake--backend-state-disabled state)
        (flymake-error
         "Unexpected report from disabled backend %s" backend))
       ((progn
          (setq expected-token (flymake--backend-state-running state))
          (null expected-token))
        ;; should never happen
        (flymake-error "Unexpected report from stopped backend %s" backend))
       ((not (or (eq expected-token token)
                 force))
        (flymake-error "Obsolete report from backend %s with explanation %s"
                       backend explanation))
       ((eq :panic report-action)
        (flymake--disable-backend backend explanation))
       ((not (listp report-action))
        (flymake--disable-backend backend
                                  (format "Unknown action %S" report-action))
        (flymake-error "Expected report, but got unknown key %s" report-action))
       (t
        (setq new-diags report-action)
        (save-restriction
          (widen)
          ;; Before adding to backend's diagnostic list, decide if
          ;; some or all must be deleted.  When deleting, also delete
          ;; the associated overlay.
          (cond
           (region
            (dolist (diag (flymake--backend-state-diags state))
              (let ((diag-beg (flymake--diag-beg diag))
                    (diag-end (flymake--diag-beg diag)))
                (when (and (< diag-beg (cdr region))
                           (> diag-end (car region)))
                  (delete-overlay (flymake--diag-overlay diag))
                  (setf (flymake--backend-state-diags state)
                        (delq diag (flymake--backend-state-diags state)))))))
           (first-report
            (dolist (diag (flymake--backend-state-diags state))
              (delete-overlay (flymake--diag-overlay diag)))
            (setf (flymake--backend-state-diags state) nil)))
          ;; Now make new ones
          (mapc (lambda (diag)
                  (let ((overlay (flymake--highlight-line diag)))
                    (setf (flymake--diag-backend diag) backend
                          (flymake--diag-overlay diag) overlay)))
                new-diags)
          (setf (flymake--backend-state-diags state)
                (append new-diags (flymake--backend-state-diags state)))
          (when flymake-check-start-time
            (flymake-log :debug "backend %s reported %d diagnostics in %.2f second(s)"
                         backend
                         (length new-diags)
                         (- (float-time) flymake-check-start-time)))
          (when (and (get-buffer (flymake--diagnostics-buffer-name))
                     (get-buffer-window (flymake--diagnostics-buffer-name))
                     (null (cl-set-difference (flymake-running-backends)
                                              (flymake-reporting-backends))))
            (flymake-show-diagnostics-buffer))))))))

(defun flymake-make-report-fn (backend &optional token)
  "Make a suitable anonymous report function for BACKEND.
BACKEND is used to help Flymake distinguish different diagnostic
sources.  If provided, TOKEN helps Flymake distinguish between
different runs of the same backend."
  (let ((buffer (current-buffer)))
    (lambda (&rest args)
      (when (buffer-live-p buffer)
        (with-current-buffer buffer
          (apply #'flymake--handle-report backend token args))))))

(defun flymake--collect (fn &optional message-prefix)
  "Collect Flymake backends matching FN.
If MESSAGE-PREFIX, echo a message using that prefix"
  (unless flymake--backend-state
    (user-error "Flymake is not initialized"))
  (let (retval)
    (maphash (lambda (backend state)
               (when (funcall fn state) (push backend retval)))
             flymake--backend-state)
    (when message-prefix
      (message "%s%s"
               message-prefix
               (mapconcat (lambda (s) (format "%s" s))
                          retval ", ")))
    retval))

(defun flymake-running-backends ()
  "Compute running Flymake backends in current buffer."
  (interactive)
  (flymake--collect #'flymake--backend-state-running
                    (and (called-interactively-p 'interactive)
                         "Running backends: ")))

(defun flymake-disabled-backends ()
  "Compute disabled Flymake backends in current buffer."
  (interactive)
  (flymake--collect #'flymake--backend-state-disabled
                    (and (called-interactively-p 'interactive)
                         "Disabled backends: ")))

(defun flymake-reporting-backends ()
  "Compute reporting Flymake backends in current buffer."
  (interactive)
  (flymake--collect #'flymake--backend-state-reported-p
                    (and (called-interactively-p 'interactive)
                         "Reporting backends: ")))

(defun flymake--disable-backend (backend &optional explanation)
  "Disable BACKEND because EXPLANATION.
If it is running also stop it."
  (flymake-log :warning "Disabling backend %s because %s" backend explanation)
  (flymake--with-backend-state backend state
    (setf (flymake--backend-state-running state) nil
          (flymake--backend-state-disabled state) explanation
          (flymake--backend-state-reported-p state) t)))

(defun flymake--run-backend (backend &optional args)
  "Run the backend BACKEND, re-enabling if necessary.
ARGS is a keyword-value plist passed to the backend along
with a report function."
  (flymake-log :debug "Running backend %s" backend)
  (let ((run-token (cl-gensym "backend-token")))
    (flymake--with-backend-state backend state
      (setf (flymake--backend-state-running state) run-token
            (flymake--backend-state-disabled state) nil
            (flymake--backend-state-reported-p state) nil))
    ;; FIXME: Should use `condition-case-unless-debug' here, but don't
    ;; for two reasons: (1) that won't let me catch errors from inside
    ;; `ert-deftest' where `debug-on-error' appears to be always
    ;; t. (2) In cases where the user is debugging elisp somewhere
    ;; else, and using flymake, the presence of a frequently
    ;; misbehaving backend in the global hook (most likely the legacy
    ;; backend) will trigger an annoying backtrace.
    ;;
    (condition-case err
        (apply backend (flymake-make-report-fn backend run-token)
               args)
      (error
       (flymake--disable-backend backend err)))))

(defvar-local flymake--recent-changes nil
  "Recent changes collected by `flymake-after-change-function'.")

(defun flymake-start (&optional deferred force)
  "Start a syntax check for the current buffer.
DEFERRED is a list of symbols designating conditions to wait for
before actually starting the check.  If it is nil (the list is
empty), start it immediately, else defer the check to when those
conditions are met.  Currently recognized conditions are
`post-command', for waiting until the current command is over,
`on-display', for waiting until the buffer is actually displayed
in a window.  If DEFERRED is t, wait for all known conditions.

With optional FORCE run even disabled backends.

Interactively, with a prefix arg, FORCE is t."
  (interactive (list nil current-prefix-arg))
  (let ((deferred (if (eq t deferred)
                      '(post-command on-display)
                    deferred))
        (buffer (current-buffer)))
    (cl-labels
        ((start-post-command
          ()
          (remove-hook 'post-command-hook #'start-post-command
                       nil)
          ;; The buffer may have disappeared already, e.g. because of
          ;; code like `(with-temp-buffer (python-mode) ...)'.
          (when (buffer-live-p buffer)
            (with-current-buffer buffer
              (flymake-start (remove 'post-command deferred) force))))
         (start-on-display
          ()
          (remove-hook 'window-configuration-change-hook #'start-on-display
                       'local)
          (flymake-start (remove 'on-display deferred) force)))
      (cond ((and (memq 'post-command deferred)
                  this-command)
             (add-hook 'post-command-hook
                       #'start-post-command
                       'append nil))
            ((and (memq 'on-display deferred)
                  (not (get-buffer-window (current-buffer))))
             (add-hook 'window-configuration-change-hook
                       #'start-on-display
                       'append 'local))
            (t
             (setq flymake-check-start-time (float-time))
             (let ((backend-args
                    (and
                     flymake--recent-changes
                     (list :recent-changes
                           flymake--recent-changes
                           :changes-start
                           (cl-reduce
                            #'min (mapcar #'car flymake--recent-changes))
                           :changes-end
                           (cl-reduce
                            #'max (mapcar #'cadr flymake--recent-changes))))))
               (setq flymake--recent-changes nil)
               (run-hook-wrapped
                'flymake-diagnostic-functions
                (lambda (backend)
                  (cond
                   ((and (not force)
                         (flymake--with-backend-state backend state
                           (flymake--backend-state-disabled state)))
                    (flymake-log :debug "Backend %s is disabled, not starting"
                                 backend))
                   (t
                    (flymake--run-backend backend backend-args)))
                  nil))))))))

(defvar flymake-mode-map
  (let ((map (make-sparse-keymap))) map)
  "Keymap for `flymake-mode'")

;;;###autoload
(define-minor-mode flymake-mode
  "Toggle Flymake mode on or off.

Flymake is an Emacs minor mode for on-the-fly syntax checking.
Flymake collects diagnostic information from multiple sources,
called backends, and visually annotates the buffer with the
results.

Flymake performs these checks while the user is editing.  The
customization variables `flymake-start-on-flymake-mode',
`flymake-no-changes-timeout' and
`flymake-start-syntax-check-on-newline' determine the exact
circumstances whereupon Flymake decides to initiate a check of
the buffer.

The commands `flymake-goto-next-error' and
`flymake-goto-prev-error' can be used to navigate among Flymake
diagnostics annotated in the buffer.

The visual appearance of each type of diagnostic can be changed
by setting properties `flymake-overlay-control', `flymake-bitmap'
and `flymake-severity' on the symbols of diagnostic types (like
`:error', `:warning' and `:note').

Activation or deactivation of backends used by Flymake in each
buffer happens via the special hook
`flymake-diagnostic-functions'.

Some backends may take longer than others to respond or complete,
and some may decide to disable themselves if they are not
suitable for the current buffer. The commands
`flymake-running-backends', `flymake-disabled-backends' and
`flymake-reporting-backends' summarize the situation, as does the
special *Flymake log* buffer."  :group 'flymake :lighter
  flymake--mode-line-format :keymap flymake-mode-map
  (cond
   ;; Turning the mode ON.
   (flymake-mode
    (add-hook 'after-change-functions 'flymake-after-change-function nil t)
    (add-hook 'after-save-hook 'flymake-after-save-hook nil t)
    (add-hook 'kill-buffer-hook 'flymake-kill-buffer-hook nil t)

    (setq flymake--backend-state (make-hash-table))
    (setq flymake--recent-changes nil)

    (when flymake-start-on-flymake-mode (flymake-start t)))

   ;; Turning the mode OFF.
   (t
    (remove-hook 'after-change-functions 'flymake-after-change-function t)
    (remove-hook 'after-save-hook 'flymake-after-save-hook t)
    (remove-hook 'kill-buffer-hook 'flymake-kill-buffer-hook t)
    ;;+(remove-hook 'find-file-hook (function flymake-find-file-hook) t)

    (mapc #'delete-overlay (flymake--overlays))

    (when flymake-timer
      (cancel-timer flymake-timer)
      (setq flymake-timer nil)))))

(defun flymake--schedule-timer-maybe ()
  "(Re)schedule an idle timer for checking the buffer.
Do it only if `flymake-no-changes-timeout' is non-nil."
  (when flymake-timer (cancel-timer flymake-timer))
  (when flymake-no-changes-timeout
    (setq
     flymake-timer
     (run-with-idle-timer
      (seconds-to-time flymake-no-changes-timeout)
      nil
      (lambda (buffer)
        (when (buffer-live-p buffer)
          (with-current-buffer buffer
            (when (and flymake-mode
                       flymake-no-changes-timeout)
	      (flymake-log
               :debug "starting syntax check after idle for %s seconds"
               flymake-no-changes-timeout)
	      (flymake-start t))
            (setq flymake-timer nil))))
      (current-buffer)))))

;;;###autoload
(defun flymake-mode-on ()
  "Turn Flymake mode on."
  (flymake-mode 1))

;;;###autoload
(defun flymake-mode-off ()
  "Turn Flymake mode off."
  (flymake-mode 0))

(make-obsolete 'flymake-mode-on 'flymake-mode "26.1")
(make-obsolete 'flymake-mode-off 'flymake-mode "26.1")

(defun flymake-after-change-function (start stop _len)
  "Start syntax check for current buffer if it isn't already running.
START and STOP and LEN are as in `after-change-functions'."
  (let((new-text (buffer-substring start stop)))
    (push (list start stop new-text) flymake--recent-changes)
    (when (and flymake-start-syntax-check-on-newline (equal new-text "\n"))
      (flymake-log :debug "starting syntax check as new-line has been seen")
      (flymake-start t))
    (flymake--schedule-timer-maybe)))

(defun flymake-after-save-hook ()
  (when flymake-start-on-save-buffer
    (flymake-log :debug "starting syntax check as buffer was saved")
    (flymake-start t)))

(defun flymake-kill-buffer-hook ()
  (when flymake-timer
    (cancel-timer flymake-timer)
    (setq flymake-timer nil)))

(defun flymake-find-file-hook ()
  (unless (or flymake-mode
              (null flymake-diagnostic-functions))
    (flymake-mode)
    (flymake-log :warning "Turned on in `flymake-find-file-hook'")))

(defun flymake-goto-next-error (&optional n filter interactive)
  "Go to Nth next Flymake diagnostic that matches FILTER.
Interactively, always move to the next diagnostic.  With a prefix
arg, skip any diagnostics with a severity less than `:warning'.

If `flymake-wrap-around' is non-nil and no more next diagnostics,
resumes search from top.

FILTER is a list of diagnostic types.  Only diagnostics with
matching severities matching are considered.  If nil (the
default) no filter is applied."
  ;; TODO: let filter be a number, a severity below which diags are
  ;; skipped.
  (interactive (list 1
                     (if current-prefix-arg
                         '(:error :warning))
                     t))
  (let* ((n (or n 1))
         (ovs (flymake--overlays :filter
                                 (lambda (ov)
                                   (let ((diag (overlay-get
                                                ov
                                                'flymake-diagnostic)))
                                     (and diag
                                          (or
                                           (not filter)
                                           (cl-find
                                            (flymake--severity
                                             (flymake--diag-type diag))
                                            filter :key #'flymake--severity)))))
                                 :compare (if (cl-plusp n) #'< #'>)
                                 :key #'overlay-start))
         (tail (cl-member-if (lambda (ov)
                               (if (cl-plusp n)
                                   (> (overlay-start ov)
                                      (point))
                                 (< (overlay-start ov)
                                    (point))))
                             ovs))
         (chain (if flymake-wrap-around
                    (if tail
                        (progn (setcdr (last tail) ovs) tail)
                      (and ovs (setcdr (last ovs) ovs)))
                  tail))
         (target (nth (1- n) chain)))
    (cond (target
           (goto-char (overlay-start target))
           (when interactive
             (message
              "%s"
              (funcall (overlay-get target 'help-echo)
                       (selected-window) target (point)))))
          (interactive
           (user-error "No more Flymake diagnostics%s"
                       (if filter
                           (format " of %s severity"
                                   (mapconcat #'symbol-name filter ", ")) ""))))))

(defun flymake-goto-prev-error (&optional n filter interactive)
  "Go to Nth previous Flymake diagnostic that matches FILTER.
Interactively, always move to the previous diagnostic.  With a
prefix arg, skip any diagnostics with a severity less than
`:warning'.

If `flymake-wrap-around' is non-nil and no more previous
diagnostics, resumes search from bottom.

FILTER is a list of diagnostic types.  Only diagnostics with
matching severities matching are considered.  If nil (the
default) no filter is applied."
  (interactive (list 1 (if current-prefix-arg
                           '(:error :warning))
                     t))
  (flymake-goto-next-error (- (or n 1)) filter interactive))


;;; Mode-line and menu
;;;
(easy-menu-define flymake-menu flymake-mode-map "Flymake"
  `("Flymake"
    [ "Go to next problem"      flymake-goto-next-error t ]
    [ "Go to previous problem"  flymake-goto-prev-error t ]
    [ "Check now"               flymake-start t ]
    [ "List all problems"       flymake-show-diagnostics-buffer t ]
    "--"
    [ "Go to log buffer"        flymake-switch-to-log-buffer t ]
    [ "Turn off Flymake"        flymake-mode t ]))

(defvar flymake--mode-line-format `(:eval (flymake--mode-line-format)))

(put 'flymake--mode-line-format 'risky-local-variable t)

(defun flymake--mode-line-format ()
  "Produce a pretty minor mode indicator."
  (let* ((known (hash-table-keys flymake--backend-state))
         (running (flymake-running-backends))
         (disabled (flymake-disabled-backends))
         (reported (flymake-reporting-backends))
         (diags-by-type (make-hash-table))
         (all-disabled (and disabled (null running)))
         (some-waiting (cl-set-difference running reported)))
    (maphash (lambda (_b state)
               (mapc (lambda (diag)
                       (push diag
                             (gethash (flymake--diag-type diag)
                                      diags-by-type)))
                     (flymake--backend-state-diags state)))
             flymake--backend-state)
    `((:propertize " Flymake"
                   mouse-face mode-line-highlight
                   help-echo
                   ,(concat (format "%s known backends\n" (length known))
                            (format "%s running\n" (length running))
                            (format "%s disabled\n" (length disabled))
                            "mouse-1: Display minor mode menu\n"
                            "mouse-2: Show help for minor mode")
                   keymap
                   ,(let ((map (make-sparse-keymap)))
                      (define-key map [mode-line down-mouse-1]
                        flymake-menu)
                      (define-key map [mode-line mouse-2]
                        (lambda ()
                          (interactive)
                          (describe-function 'flymake-mode)))
                      map))
      ,@(pcase-let ((`(,ind ,face ,explain)
                     (cond ((null known)
                            `("?" mode-line "No known backends"))
                           (some-waiting
                            `("Wait" compilation-mode-line-run
                              ,(format "Waiting for %s running backend(s)"
                                       (length some-waiting))))
                           (all-disabled
                            `("!" compilation-mode-line-run
                              "All backends disabled"))
                           (t
                            `(nil nil nil)))))
          (when ind
            `((":"
               (:propertize ,ind
                            face ,face
                            help-echo ,explain
                            keymap
                            ,(let ((map (make-sparse-keymap)))
                               (define-key map [mode-line mouse-1]
                                 'flymake-switch-to-log-buffer)
                               map))))))
      ,@(unless (or all-disabled
                    (null known))
          (cl-loop
           for (type . severity)
           in (cl-sort (mapcar (lambda (type)
                                 (cons type (flymake--severity type)))
                               (cl-union (hash-table-keys diags-by-type)
                                         '(:error :warning)
                                         :key #'flymake--severity))
                       #'>
                       :key #'cdr)
           for diags = (gethash type diags-by-type)
           for face = (flymake--lookup-type-property type
                                                     'mode-line-face
                                                     'compilation-error)
           when (or diags
                    (>= severity (warning-numeric-level :warning)))
           collect `(:propertize
                     ,(format "%d" (length diags))
                     face ,face
                     mouse-face mode-line-highlight
                     keymap
                     ,(let ((map (make-sparse-keymap))
                            (type type))
                        (define-key map (vector 'mode-line
                                                mouse-wheel-down-event)
                          (lambda (event)
                            (interactive "e")
                            (with-selected-window (posn-window (event-start event))
                              (flymake-goto-prev-error 1 (list type) t))))
                        (define-key map (vector 'mode-line
                                                mouse-wheel-up-event)
                          (lambda (event)
                            (interactive "e")
                            (with-selected-window (posn-window (event-start event))
                              (flymake-goto-next-error 1 (list type) t))))
                        map)
                     help-echo
                     ,(concat (format "%s diagnostics of type %s\n"
                                      (propertize (format "%d"
                                                          (length diags))
                                                  'face face)
                                      (propertize (format "%s" type)
                                                  'face face))
                              (format "%s/%s: previous/next of this type"
                                      mouse-wheel-down-event
                                      mouse-wheel-up-event)))
           into forms
           finally return
           `((:propertize "[")
             ,@(cl-loop for (a . rest) on forms by #'cdr
                        collect a when rest collect
                        '(:propertize " "))
             (:propertize "]")))))))

;;; Diagnostics buffer

(defvar-local flymake--diagnostics-buffer-source nil)

(defvar flymake-diagnostics-buffer-mode-map
  (let ((map (make-sparse-keymap)))
    (define-key map (kbd "RET") 'flymake-goto-diagnostic)
    (define-key map (kbd "SPC") 'flymake-show-diagnostic)
    map))

(defun flymake-show-diagnostic (pos &optional other-window)
  "Show location of diagnostic at POS."
  (interactive (list (point) t))
  (let* ((id (or (tabulated-list-get-id pos)
                 (user-error "Nothing at point")))
         (diag (plist-get id :diagnostic)))
    (with-current-buffer (flymake--diag-buffer diag)
      (with-selected-window
          (display-buffer (current-buffer) other-window)
        (goto-char (flymake--diag-beg diag))
        (pulse-momentary-highlight-region (flymake--diag-beg diag)
                                          (flymake--diag-end diag)
                                          'highlight))
      (current-buffer))))

(defun flymake-goto-diagnostic (pos)
  "Show location of diagnostic at POS.
POS can be a buffer position or a button"
  (interactive "d")
  (pop-to-buffer
   (flymake-show-diagnostic (if (button-type pos) (button-start pos) pos))))

(defun flymake--diagnostics-buffer-entries ()
  (with-current-buffer flymake--diagnostics-buffer-source
    (cl-loop for diag in
             (cl-sort (flymake-diagnostics) #'< :key #'flymake-diagnostic-beg)
             for (line . col) =
             (save-excursion
               (goto-char (flymake--diag-beg diag))
               (cons (line-number-at-pos)
                     (- (point)
                        (line-beginning-position))))
             for type = (flymake--diag-type diag)
             collect
             (list (list :diagnostic diag
                         :line line
                         :severity (flymake--lookup-type-property
                                    type
                                    'severity (warning-numeric-level :error)))
                   `[,(format "%s" line)
                     ,(format "%s" col)
                     ,(propertize (format "%s" type)
                                  'face (flymake--lookup-type-property
                                         type 'mode-line-face 'flymake-error))
                     (,(format "%s" (flymake--diag-text diag))
                      mouse-face highlight
                      help-echo "mouse-2: visit this diagnostic"
                      face nil
                      action flymake-goto-diagnostic
                      mouse-action flymake-goto-diagnostic)]))))

(define-derived-mode flymake-diagnostics-buffer-mode tabulated-list-mode
  "Flymake diagnostics"
  "A mode for listing Flymake diagnostics."
  (setq tabulated-list-format
        `[("Line" 5 (lambda (l1 l2)
                      (< (plist-get (car l1) :line)
                         (plist-get (car l2) :line)))
           :right-align t)
          ("Col" 3 nil :right-align t)
          ("Type" 8 (lambda (l1 l2)
                      (< (plist-get (car l1) :severity)
                         (plist-get (car l2) :severity))))
          ("Message" 0 t)])
  (setq tabulated-list-entries
        'flymake--diagnostics-buffer-entries)
  (tabulated-list-init-header))

(defun flymake--diagnostics-buffer-name ()
  (format "*Flymake diagnostics for %s*" (current-buffer)))

(defun flymake-show-diagnostics-buffer ()
  "Show a list of Flymake diagnostics for current buffer."
  (interactive)
  (let* ((name (flymake--diagnostics-buffer-name))
         (source (current-buffer))
         (target (or (get-buffer name)
                     (with-current-buffer (get-buffer-create name)
                       (flymake-diagnostics-buffer-mode)
                       (setq flymake--diagnostics-buffer-source source)
                       (current-buffer)))))
    (with-current-buffer target
      (revert-buffer)
      (display-buffer (current-buffer)))))

(provide 'flymake)

(require 'flymake-proc)

;;; flymake.el ends here