1 files changed, 32 insertions, 16 deletions

diff --git a/nix/lazy-deps/default.nix b/nix/lazy-deps/default.nix
index 3cce48d8a5..fbdb30b38e 100644
--- a/nix/lazy-deps/default.nix
+++ b/nix/lazy-deps/default.nix
@@ -9,11 +9,11 @@
 # evaluation, and expects both `git` and `nix-build` to exist in the
 # user's $PATH. If required, this can be done in the shell
 # configuration invoking this function.
-{ pkgs, ... }:
+{ pkgs, lib, ... }:
 
 let
   inherit (builtins) attrNames attrValues mapAttrs;
-  inherit (pkgs.lib) concatStringsSep;
+  inherit (lib) fix concatStringsSep;
 
   # Create the case statement for a command invocations, optionally
   # overriding the `TARGET_TOOL` variable.
@@ -28,20 +28,21 @@ let
 
   invocations = tools: concatStringsSep "\n" (attrValues (mapAttrs invoke tools));
 in
+fix (self:
 
 # Attribute set of tools that should be lazily-added to the $PATH.
-
-  # The name of each attribute is used as the command name (on $PATH).
-  # It must contain the keys 'attr' (containing the Nix attribute path
-  # to the tool's derivation from the top-level), and may optionally
-  # contain the key 'cmd' to override the name of the binary inside the
-  # derivation.
+#
+# The name of each attribute is used as the command name (on $PATH).
+# It must contain the keys 'attr' (containing the Nix attribute path
+# to the tool's derivation from the top-level), and may optionally
+# contain the key 'cmd' to override the name of the binary inside the
+# derivation.
 tools:
 
-pkgs.writeTextFile {
-  name = "lazy-dispatch";
-  executable = true;
-  destination = "/bin/__dispatch";
+pkgs.runCommandNoCC "lazy-dispatch"
+{
+  passthru.overrideDeps = newTools: self (tools // newTools);
+  passthru.tools = tools;
 
   text = ''
     #!${pkgs.runtimeShell}
@@ -68,8 +69,23 @@ pkgs.writeTextFile {
     exec "''${TARGET_TOOL}" "''${@}"
   '';
 
-  checkPhase = ''
-    ${pkgs.stdenv.shellDryRun} "$target"
-    ${concatStringsSep "\n" (map link (attrNames tools))}
-  '';
+  # Access this to get a compatible nix-shell
+  passthru.devShell = pkgs.mkShellNoCC {
+    name = "${self.name}-shell";
+    packages = [ self ];
+  };
 }
+  ''
+    # Write the dispatch code
+    target=$out/bin/__dispatch
+    mkdir -p "$(dirname "$target")"
+    echo "$text" > $target
+    chmod +x $target
+
+    # Add symlinks from all the tools to the dispatch
+    ${concatStringsSep "\n" (map link (attrNames tools))}
+
+    # Check that it's working-ish
+    ${pkgs.stdenv.shellDryRun} $target
+  ''
+)