Add $__fish_config_dir variable

Contains the path to the user config.fish (e.g. ~/.config/fish)
without having to do the `set -q XDG_CONFIG_HOME` dance.

See #5270.

doc_src/index.hdr.in

@@ -1250,14 +1250,14 @@ Configuration files are evaluated in the following order:
 - Configuration shipped with fish, which should not be edited, in `$__fish_data_dir/config.fish` (usually `/usr/share/fish/config.fish`).
 - System-wide configuration files, where administrators can include initialization that should be run for all users on the system - similar to `/etc/profile` for POSIX-style shells - in `$__fish_sysconf_dir` (usually `/etc/fish/config.fish`);
 - Configuration snippets in files ending in `.fish`, in the directories:
-  - `$XDG_CONFIG_HOME/fish/conf.d` (by default, `~/.config/fish/conf.d/`)
+  - `$__fish_config_dir/conf.d` (by default, `~/.config/fish/conf.d/`)
   - `$__fish_sysconf_dir/conf.d` (by default, `/etc/fish/conf.d`)
   - `/usr/share/fish/vendor_conf.d` (set at compile time; by default, `$__fish_data_dir/conf.d`)
 
   If there are multiple files with the same name in these directories, only the first will be executed.
   They are executed in order of their filename, sorted (like globs) in a natural order (i.e. "01" sorts before "2").
 
-- User initialization, usually in `~/.config/fish/config.fish` (controlled by the `XDG_CONFIG_HOME` environment variable).
+- User initialization, usually in `~/.config/fish/config.fish` (controlled by the `XDG_CONFIG_HOME` environment variable, and accessible as `$__fish_config_dir`).
 
 These paths are controlled by parameters set at build, install, or run time, and may vary from the defaults listed above.
 

share/config.fish

@@ -62,10 +62,10 @@ end
 # unless they already exist
 #
 
-set -l configdir ~/.config
+set -g __fish_config_dir ~/.config
 
 if set -q XDG_CONFIG_HOME
-    set configdir $XDG_CONFIG_HOME
+    set __fish_config_dir $XDG_CONFIG_HOME
 end
 
 set -l userdatadir ~/.local/share
@@ -90,7 +90,7 @@ end
 # default functions/completions are included in the respective path.
 
 if not set -q fish_function_path
-    set fish_function_path $configdir/fish/functions $__fish_sysconf_dir/functions $__extra_functionsdir $__fish_data_dir/functions
+    set fish_function_path $__fish_config_dir/functions $__fish_sysconf_dir/functions $__extra_functionsdir $__fish_data_dir/functions
 end
 
 if not contains -- $__fish_data_dir/functions $fish_function_path
@@ -98,7 +98,7 @@ if not contains -- $__fish_data_dir/functions $fish_function_path
 end
 
 if not set -q fish_complete_path
-    set fish_complete_path $configdir/fish/completions $__fish_sysconf_dir/completions $__extra_completionsdir $__fish_data_dir/completions $userdatadir/fish/generated_completions
+    set fish_complete_path $__fish_config_dir/completions $__fish_sysconf_dir/completions $__extra_completionsdir $__fish_data_dir/completions $userdatadir/fish/generated_completions
 end
 
 if not contains -- $__fish_data_dir/completions $fish_complete_path
@@ -294,7 +294,7 @@ end
 # As last part of initialization, source the conf directories.
 # Implement precedence (User > Admin > Extra (e.g. vendors) > Fish) by basically doing "basename".
 set -l sourcelist
-for file in $configdir/fish/conf.d/*.fish $__fish_sysconf_dir/conf.d/*.fish $__extra_confdir/*.fish
+for file in $__fish_config_dir/conf.d/*.fish $__fish_sysconf_dir/conf.d/*.fish $__extra_confdir/*.fish
     set -l basename (string replace -r '^.*/' '' -- $file)
     contains -- $basename $sourcelist
     and continue

share/functions/funcsave.fish

@@ -8,12 +8,7 @@ function funcsave --description "Save the current definition of all specified fu
         return 0
     end
 
-    set -l configdir ~/.config
-    if set -q XDG_CONFIG_HOME
-        set configdir $XDG_CONFIG_HOME
-    end
-
-    if not mkdir -p $configdir/fish/functions
+    if not mkdir -p $__fish_config_dir/functions
         printf (_ "%s: Could not create configuration directory\n") funcsave
         return 1
     end
@@ -21,7 +16,7 @@ function funcsave --description "Save the current definition of all specified fu
     set -l retval 0
     for funcname in $argv
         if functions -q -- $funcname
-            functions -- $funcname >$configdir/fish/functions/$funcname.fish
+            functions -- $funcname >$__fish_config_dir/functions/$funcname.fish
         else
             printf (_ "%s: Unknown function '%s'\n") funcsave $funcname
             set retval 1