shell: stop fish from having to be built every time

Drop the patch to fish source code, instead opting
to employ fish's inbuilt share/fish/vendor_conf.d
to add custom code to fish.

This is both a bit simpler, and makes it so fish does not
have to be compiled on every update to it's source / to my configuration.

packages/shell/default.nix

@@ -1,34 +1,42 @@
-# This shell setup was inspired by sioodmy. Check out his setup!
+# This shell setup was originally inspired by sioodmy.
+# Some further cool tricks, like using vendor_conf.d to avoid having
+# to build fish myself, are taken from viperml's setup.
 {pkgs, ...}: let
+  inherit (pkgs) lib;
+  inherit (lib.strings) concatStringsSep;
+  inherit (lib.attrsets) mapAttrsToList;
+
   toml = pkgs.formats.toml {};
   starship-config = import ./starship.nix;
   aliases = import ./aliases.nix {inherit pkgs;};
+  vendorConf = "share/fish/vendor_conf.d";
 
-  fishinit = import ./fishinit.nix {inherit pkgs aliasesStr;};
+  fishinit = import ./fishinit.nix {
+    inherit
+      pkgs
+      aliasesStr
+      vendorConf
+      ;
+  };
 
   aliasesStr =
     mapAttrsToList (k: v: "alias ${k}=\"${v}\"") aliases
     |> concatStringsSep "\n";
 
   packages = import ./packages.nix pkgs;
-
-  # this was taken from viperml, check out his config for this!
-  custom-fish = pkgs.fish.overrideAttrs (old: {
-    patches = [./fish-on-tmpfs.patch];
-    doCheck = false;
-    postInstall =
-      old.postInstall
-      + ''
-        echo "source ${fishinit}" >> $out/etc/fish/config.fish
-      '';
-  });
 in
   (pkgs.symlinkJoin {
     name = "fish";
-    paths = [custom-fish] ++ packages;
+    paths = [pkgs.fish] ++ packages;
     nativeBuildInputs = [pkgs.makeWrapper];
     postBuild = ''
-      wrapProgram $out/bin/fish --set STARSHIP_CONFIG "${toml.generate "starship.toml" starship-config}" \
+      wrapProgram $out/bin/fish \
+      --set STARSHIP_CONFIG "${toml.generate "starship.toml" starship-config}" \
+      --prefix XDG_DATA_DIRS : "${
+        lib.makeSearchPathOutput "out" "share" [
+          fishinit
+        ]
+      }"
     '';
   })
   .overrideAttrs (_: {

packages/shell/fish-on-tmpfs.patch

@@ -1,10 +0,0 @@
---- a/src/path.rs
-+++ b/src/path.rs
-@@ -781,7 +781,7 @@ fn get_cache_directory() -> &'static BaseDirectory {
- 
- fn get_config_directory() -> &'static BaseDirectory {
-     static DIR: Lazy<BaseDirectory> =
--        Lazy::new(|| make_base_directory(L!("XDG_CONFIG_HOME"), L!("/.config/fish")));
-+        Lazy::new(|| make_base_directory(L!("XDG_RUNTIME_DIR"), L!("/.config/fish")));
-     &DIR
- }

packages/shell/fishinit.nix

@@ -1,9 +1,11 @@
 {
   pkgs,
   aliasesStr,
+  vendorConf,
 }:
-pkgs.writeText "config.fish" ''
-
+pkgs.writeTextDir "${vendorConf}/blox_config.fish"
+# fish
+''
   # source ${pkgs.fishPlugins.sponge}/share/zsh-defer/zsh-defer.plugin.zsh
   ${pkgs.atuin}/bin/atuin init fish | source
   ${pkgs.zoxide}/bin/zoxide init fish | source
@@ -11,6 +13,10 @@ pkgs.writeText "config.fish" ''
   ${pkgs.direnv}/bin/direnv hook fish | source
   ${pkgs.pay-respects}/bin/pay-respects fish --alias f --nocnf | source
 
+  # I need to source /etc/profile using foreign-env, to get stuff set by nixos, e.g. environment.systemVariables.
+  # set -p fish_function_path ${pkgs.fishPlugins.foreign-env}/share/fish/vendor_functions.d
+
+  # fenv source /etc/profile
 
   source ${./config.fish}