provide a better experience when user presses \cC

Fixes fish-shell#2904

share/functions/__fish_cancel_commandline.fish

@@ -0,0 +1,13 @@
+# This is meant to be bound to something like \cC.
+function __fish_cancel_commandline
+    set -l cmd (commandline)
+    if test -n "$cmd"
+        commandline -C 1000000
+        echo (set_color -b bryellow black)"^C"(set_color normal)
+        for i in (seq (commandline -L))
+            echo ""
+        end
+        commandline ""
+        commandline -f repaint
+    end
+end

share/functions/fish_default_key_bindings.fish

@@ -109,7 +109,7 @@ function fish_default_key_bindings -d "Default (Emacs-like) key bindings for fis
 	bind $argv \el __fish_list_current_token
 	bind $argv \ew 'set tok (commandline -pt); if test $tok[1]; echo; whatis $tok[1]; commandline -f repaint; end'
 	bind $argv \cl 'clear; commandline -f repaint'
-	bind $argv \cc 'commandline ""'
+	bind $argv \cc __fish_cancel_commandline
 	bind $argv \cu backward-kill-line
 	bind $argv \cw backward-kill-path-component
 	bind $argv \ed 'set -l cmd (commandline); if test -z "$cmd"; echo; dirh; commandline -f repaint; else; commandline -f kill-word; end'

share/functions/fish_vi_key_bindings.fish

@@ -22,22 +22,20 @@ function fish_vi_key_bindings --description 'vi-like key bindings for fish'
     # Remove the default self-insert bindings in default mode
     bind -e "" -M default
     # Add way to kill current command line while in insert mode.
-    bind -M insert \cc 'commandline ""'
+    bind -M insert \cc __fish_cancel_commandline
     # Add a way to switch from insert to normal (command) mode.
     bind -M insert -m default \e backward-char force-repaint
 
-    #
-    # normal (command) mode
-    #
+    # Default (command) mode
     bind :q exit
     bind \cd exit
-    bind \cc 'commandline ""'
+    bind -m insert \cc __fish_cancel_commandline
     bind h backward-char
     bind l forward-char
     bind \e\[C forward-char
     bind \e\[D backward-char
 
-    # Some linux VTs output these (why?)
+    # Some terminals output these when they're in in keypad mode.
     bind \eOC forward-char
     bind \eOD backward-char