Enhance the eshell with its built-in ansi-color support

* layers/+tools/shell/packages.el: Bump the xterm-color package for
* emacs < 29.0.50.
* layers/+tools/shell/README.org: Document for the changes.

layers/+tools/shell/README.org

@@ -286,6 +286,8 @@ Some advanced configuration is setup for =eshell= in this layer:
 - add support for auto-completion via =company= (when the =auto-completion=
  layer is installed)
 - pressing ~i~ in normal state will automatically jump to the prompt
+- color support with package ~xterm-color~ on Emacs28 and before
+- color support with built-in ~ansi-color~ by default on Emacs29 and later
 
 * Key bindings
 

layers/+tools/shell/packages.el

@@ -40,7 +40,7 @@
  (shell :location built-in)
  shell-pop
  (term :location built-in)
- xterm-color
+ (xterm-color :toggle (version< emacs-version "29.0.50"))
  terminal-here
  vi-tilde-fringe
  window-purpose
@@ -101,26 +101,8 @@
  (add-hook 'eshell-mode-hook 'spacemacs/disable-hl-line-mode)
  (with-eval-after-load 'centered-cursor-mode
  (add-hook 'eshell-mode-hook 'spacemacs//inhibit-global-centered-cursor-mode))
- :config
-
- ;; Work around bug in eshell's preoutput-filter code.
- ;; Eshell doesn't call preoutput-filter functions in the context of the eshell
- ;; buffer. This breaks the xterm color filtering when the eshell buffer is updated
- ;; when it's not currently focused.
- ;; To remove if/when fixed upstream.
- (defun eshell-output-filter@spacemacs-with-buffer (fn process string)
- (let ((proc-buf (if process (process-buffer process)
- (current-buffer))))
- (when proc-buf
- (with-current-buffer proc-buf
- (funcall fn process string)))))
- (advice-add
- #'eshell-output-filter
- :around
- #'eshell-output-filter@spacemacs-with-buffer)
-
- (require 'esh-opt)
 
+ :config
  ;; quick commands
  (defalias 'eshell/e 'find-file-other-window)
  (defalias 'eshell/d 'dired)
@@ -314,7 +296,23 @@
  (add-hook 'comint-preoutput-filter-functions 'xterm-color-filter)
  (setq comint-output-filter-functions
  (remove 'ansi-color-process-output comint-output-filter-functions))
- (add-hook 'eshell-mode-hook 'spacemacs/init-eshell-xterm-color)))
+ (add-hook 'eshell-mode-hook 'spacemacs/init-eshell-xterm-color)
+ (with-eval-after-load 'eshell
+ ;; Work around bug in eshell's preoutput-filter code.
+ ;; Eshell doesn't call preoutput-filter functions in the context of the eshell
+ ;; buffer. This breaks the xterm color filtering when the eshell buffer is updated
+ ;; when it's not currently focused.
+ ;; To remove if/when fixed upstream.
+ (defun eshell-output-filter@spacemacs-with-buffer (fn process string)
+ (let ((proc-buf (if process (process-buffer process)
+ (current-buffer))))
+ (when proc-buf
+ (with-current-buffer proc-buf
+ (funcall fn process string)))))
+ (advice-add
+ #'eshell-output-filter
+ :around
+ #'eshell-output-filter@spacemacs-with-buffer))))
 
 (defun shell/init-terminal-here ()
  (use-package terminal-here