fish: expose session variables package

This allows fish users to source the `hm-session-vars.fish` if they are
not using the generated `config.fish` (which now sources the same file).

docs/manual/faq/session-variables.md

@@ -17,8 +17,11 @@ way. In Bash and Z shell this can be done by adding
 to your `.profile` and `.zshrc` files, respectively. The
 `hm-session-vars.sh` file should work in most Bourne-like shells. For
 fish shell, it is possible to source it using [the foreign-env
-plugin](https://github.com/oh-my-fish/plugin-foreign-env)
+plugin](https://github.com/oh-my-fish/plugin-foreign-env) or using the builtin
+[babelfish](https://github.com/bouk/babelfish)-translated variables:
 
 ``` bash
 fenv source "$HOME/.nix-profile/etc/profile.d/hm-session-vars.sh" > /dev/null
+# or
+source "$HOME/.nix-profile/etc/profile.d/hm-session-vars.fish"
 ```

modules/programs/fish.nix

@@ -388,12 +388,14 @@ let
       passAsFile = [ "text" ];
     } "env HOME=$(mktemp -d) fish_indent < $textPath > $out";
 
-  translatedSessionVariables = pkgs.runCommandLocal "hm-session-vars.fish" { } ''
+  sessionVarsFile = "etc/profile.d/hm-session-vars.fish";
+  sessionVarsPkg = pkgs.runCommandLocal "hm-session-vars.fish" { } ''
+    mkdir -p "$(dirname $out/${sessionVarsFile})"
     (echo "function setup_hm_session_vars;"
     ${pkgs.buildPackages.babelfish}/bin/babelfish \
-    <${config.home.sessionVariablesPackage}/etc/profile.d/hm-session-vars.sh
+      <${config.home.sessionVariablesPackage}/etc/profile.d/hm-session-vars.sh
     echo "end"
-    echo "setup_hm_session_vars") > $out
+    echo "setup_hm_session_vars") > $out/${sessionVarsFile}
   '';
 
 in
@@ -591,11 +593,25 @@ in
         <https://fishshell.com/docs/current/completions.html>.
       '';
     };
+
+    programs.fish.sessionVariablesPackage = mkOption {
+      type = types.package;
+      internal = true;
+      description = ''
+        The package containing the translated {file}`hm-session-vars.fish` file.
+      '';
+    };
   };
 
   config = mkIf cfg.enable (
     lib.mkMerge [
-      { home.packages = [ cfg.package ]; }
+      {
+        home.packages = [
+          cfg.package
+          cfg.sessionVariablesPackage
+        ];
+        programs.fish.sessionVariablesPackage = sessionVarsPkg;
+      }
 
       (mkIf cfg.generateCompletions (
         let
@@ -708,7 +724,7 @@ in
           set -q __fish_home_manager_config_sourced; and exit
           set -g __fish_home_manager_config_sourced 1
 
-          source ${translatedSessionVariables}
+          source ${cfg.sessionVariablesPackage}/${sessionVarsFile}
 
           ${cfg.shellInit}
 

tests/modules/programs/fish/default.nix

@@ -7,4 +7,5 @@
   fish-plugins = ./plugins.nix;
   fish-manpage = ./manpage.nix;
   fish-binds = ./binds.nix;
+  fish-session-variables = ./session-variables.nix;
 }

tests/modules/programs/fish/session-variables.nix

@@ -0,0 +1,20 @@
+{ config, ... }:
+
+{
+  config = {
+    home.sessionVariables = {
+      V1 = "v1";
+      V2 = "v2-${config.home.sessionVariables.V1}";
+    };
+
+    programs.fish.enable = true;
+
+    nmt.script = ''
+      assertFileExists home-path/etc/profile.d/hm-session-vars.fish
+      assertFileRegex home-path/etc/profile.d/hm-session-vars.fish \
+        "set -gx V1 'v1'"
+      assertFileRegex home-path/etc/profile.d/hm-session-vars.fish \
+        "set -gx V1 'v1'"
+    '';
+  };
+}