Add copyCargoTargetToOutputHook

lib/buildWithCargo.nix

@@ -1,23 +1,38 @@
 { cargo
 , configureCargoCommonVarsHook
 , configureCargoVendoredDepsHook
+, copyCargoTargetToOutputHook
 , lib
 , stdenv
 }:
 
-args@{ nativeBuildInputs ? [ ], ... }:
+{ doCopyTarget ? true
+, doCopyTargetToSeparateOutput ? doCopyTarget
+, nativeBuildInputs ? [ ]
+, outputs ? [ "out" ]
+, ...
+}@args:
 stdenv.mkDerivation (args // {
+  inherit
+    doCopyTarget
+    doCopyTargetToSeparateOutput;
+
   nativeBuildInputs = nativeBuildInputs ++ [
     cargo
     configureCargoCommonVarsHook
     configureCargoVendoredDepsHook
+    copyCargoTargetToOutputHook
   ];
 
+  outputs = outputs ++ lib.optional (doCopyTarget && doCopyTargetToSeparateOutput) "target";
+
   buildPhase = ''
     cargo check --release
   '';
 
   installPhase = ''
-    touch $out
+    runHook preInstall
+    mkdir -p $out
+    runHook postInstall
   '';
 })

pkgs/copyCargoTargetToOutputHook.sh

@@ -0,0 +1,21 @@
+copyCargoTargetToOutput() {
+  echo "Executing copyCargoTargetToOutput"
+  trap "echo Finished copyCargoTargetToOutput" RETURN
+
+  local target_dir=${CARGO_TARGET_DIR:-target}
+
+  if [ "1" != "${doCopyTarget}" ]; then
+    return
+  fi
+
+  if [ "1" = "${doCopyTargetToSeparateOutput}" ]; then
+    local dest="${target}"
+  else
+    mkdir -p "${out}"
+    local dest="${out}/target"
+  fi
+
+  mv "${target_dir}" "${dest}"
+}
+
+postInstallHooks+=(copyCargoTargetToOutput)

pkgs/default.nix

@@ -10,4 +10,9 @@
     {
       name = "configureCargoVendoredDepsHook";
     } ./configureCargoVendoredDepsHook.sh;
+
+  copyCargoTargetToOutputHook = makeSetupHook
+    {
+      name = "copyCargoTargetToOutputHook";
+    } ./copyCargoTargetToOutputHook.sh;
 }