From 771488148daf095c03ef5b61ce0778886dde8134 Mon Sep 17 00:00:00 2001
From: Dan Kessler <kesslerd@umich.edu>
Date: Fri, 16 Feb 2024 18:56:57 -0800
Subject: [PATCH] add support for remapped and aliased modes

This patch tries to make `bind-map` aware of two ways in which major modes can
be remapped: via aliasing or via `major-mode-remap-alist`.

The motivating scenario is AUCTeX, which as of version 14.0.1 has renamed
several major modes, e.g., latex-mode has been renamed as LaTeX-mode. AUCTeX
attempts to offer backwards compatibility using a mix of remapping and aliasing.
For users of emacs < 29, `latex-mode` is redefined as an alias for `LaTeX-mode`,
whereas for users of emacs 29+, `latex-mode` is remapped to `LaTeX-mode` using
`major-mode-remap-alist`.

However, if a user had configured keymaps for `latex-mode` using `bind-map`,
they will not be available in `LaTeX-mode`. This is especially problematic for
distributions like `spacemacs` which need to support users of both old and new
AUCTeX (see https://github.com/syl20bnr/spacemacs/issues/16282 for more discussion).

This patch introduces two new customizable options,
`bind-map-use-remapped-modes` and `bind-map-use-aliased-modes`. Both options
default to `t`, in which case when `bind-map` is deciding whether to activate a
given keymap, it will compare the value of `major-mode` to not only the symbol
for which the keymap was configured configured (e.g., `latex-mode`), but any
remapped or aliased modes (e.g., `'(latex-mode LaTeX-mode)`. This logic is
implemented in the new (private) function `bind-map--lookup-major-modes` to
facilitate lookup of applicable major-modes on the fly. As a result, if a user
adjusts `major-mode-remap-alist` or adjusts aliased, `bind-map`'s behavior will
change accordingly.
---
 bind-map.el | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 46 insertions(+), 1 deletion(-)

diff --git a/bind-map.el b/bind-map.el
index dee50aa..76b9435 100644
--- a/bind-map.el
+++ b/bind-map.el
@@ -128,6 +128,32 @@
   :group 'bind-map
   :type  'string)
 
+(defcustom bind-map-use-remapped-modes t
+  "If non-nil, bind-map will be aware of remapped modes. For
+example, suppose you used `bind-map' to define a keymap for
+`foo-mode', but use `major-mode-remap-alist' to remap `foo-mode'
+to `bar-mode'. If `bind-map-use-remapped-modes' is non-nil, then,
+when `bar-mode' is activated
+ (either directly or by activating `foo-mode'), the keymap for
+ `foo-mode' will be active. If you define separate keymaps for
+ `foo-mode' and `bar-mode' yet leave this option non-nil, chaos
+ may ensue."
+  :group 'bind-map
+  :type 'boolean)
+
+(defcustom bind-map-use-aliased-modes t
+  "If non-nil, bind-map will be aware of aliased modes. For example,
+suppose you used `bind-map' to define a keymap for `foo-mode',
+but `foo-mode' is actually an alias for `bar-mode'. If
+`bind-map-use-aliased-modes' is non-nil, then, when `bar-mode' is
+activated (either directly or by activating `foo-mode'), the
+keymap for `foo-mode' will be active. If you define separate
+keymaps for `foo-mode' and `bar-mode' yet leave this option
+non-nil, chaos may ensue."
+  :group 'bind-map
+  :type 'boolean)
+
+
 (defvar bind-map-evil-local-bindings '()
   "Each element takes the form (OVERRIDE-MODE STATE KEY DEF) and
 corresponds to a binding for an evil local state map.
@@ -173,11 +199,30 @@ when the major mode is an element of the cdr. See
   (dolist (entry bind-map-major-modes-alist)
     (if (boundp (car entry))
       (setf (symbol-value (car entry))
-            (not (null (member major-mode (cdr entry)))))
+            (not
+             (null
+              (member major-mode
+                      (mapcar
+                       #'bind-map--lookup-major-modes (cdr entry))))))
       (message "bind-map: %s is void in change major mode hook" (car entry)))))
 (add-hook 'change-major-mode-after-body-hook
           'bind-map-change-major-mode-after-body-hook)
 
+(defun bind-map--lookup-major-modes (mode)
+  "Return a list of implicated modes depending on the values of
+`bind-map-use-remapped-modes' and `bind-map-use-aliased-modes'.
+If both are nil, just return `mode'. If
+`bind-map-use-remapped-modes' is non-nil, also return mode to
+which it has been remapped in `major-mode-remap-alist' (if
+applicable). If `bind-map-use-aliased-modes' is non-nil, also
+return any modes for which `mode' is an alias (if applicable)."
+  (let ((r-mode
+         (or (and bind-map-use-remapped-modes
+                  (boundp 'major-mode-remap-alist)
+                  (alist-get mode major-mode-remap-alist))))
+        (a-modes (and bind-map-use-aliased-modes (function-alias-p mode))))
+    (delq nil (append (list mode r-mode) a-modes))))
+
 (defun bind-map-add-to-major-mode-list (activate-var major-mode-list)
   "Add (ACTIVATE-VAR . MAJOR-MODE-LIST) to
 `bind-map-major-modes-alist'. If ACTIVATE-VAR is already a key,