Add alias -s/--save, which saves the alias.

Also updates the `alias` documentation to mention the `-h`/`--help` option,
which was previously undocumented.

CHANGELOG.md

@@ -54,6 +54,7 @@ This section is for changes merged to the `major` branch that are not also merge
 - `functions --handlers` can be used to show event handlers (#4694).
 - Variables set in `if` and `while` conditions are available outside the block (#4820).
 - The universal variables file no longer contains the MAC address. It is now at the fixed location `.config/fish/fish_universal_variables` (#1912).
+- `alias` now has a `-s` and `--save` option to save the function generated by the alias using `funcsave` (#4878).
 
 ## Other significant changes
 - Command substitution output is now limited to 10 MB by default (#3822).

doc_src/alias.txt

@@ -3,8 +3,8 @@
 \subsection alias-synopsis Synopsis
 \fish{synopsis}
 alias
-alias NAME DEFINITION
-alias NAME=DEFINITION
+alias [OPTIONS] NAME DEFINITION
+alias [OPTIONS] NAME=DEFINITION
 \endfish
 
 \subsection alias-description Description
@@ -18,6 +18,12 @@ alias NAME=DEFINITION
 
 You cannot create an alias to a function with the same name. Note that spaces need to be escaped in the call to `alias` just like at the command line, _even inside quoted parts_.
 
+The following options are available:
+
+- `-h` or `--help` displays help about using this command.
+
+- `-s` or `--save` Automatically save the function created by the alias into your fish configuration directory using <a href='#funcsave'>funcsave</a>.
+
 \subsection alias-example Example
 
 The following code will create `rmi`, which runs `rm` with additional arguments on every invocation.

share/functions/alias.fish

@@ -1,5 +1,5 @@
 function alias --description 'Creates a function wrapping a command'
-    set -l options 'h/help'
+    set -l options 'h/help' 's/save'
     argparse -n alias --max-args=2 $options -- $argv
     or return
 
@@ -69,5 +69,8 @@ function alias --description 'Creates a function wrapping a command'
     set -l cmd_string (string escape -- "alias $argv")
     set wrapped_cmd (string join ' ' -- $first_word $body | string escape)
     echo "function $name --wraps $wrapped_cmd --description $cmd_string; $prefix $first_word $body \$argv; end" | source
+    if set -q _flag_save
+        funcsave $name
+    end
     #echo "function $name --wraps $wrapped_cmd --description $cmd_string; $prefix $first_word $body \$argv; end"
 end