Remove doCompressTarget option

* Reducing the parameter surface area for good measure, zstd compression
  works pretty well and it seems redundant to support multiple ways of
  copying the target directory around

lib/buildWithCargo.nix

@@ -60,9 +60,6 @@ in
   # access. Directory structure should basically follow the output of `cargo vendor`.
   # This can be inferred automatically if the `src` root has a Cargo.lock file.
 , cargoVendorDir ? vendorCargoDepsFromArgs args
-  # Controls whether cargo's `target` directory should be compressed when copied
-  # to the output at the end of the derivation.
-, doCompressTarget ? true
   # Controls whether cargo's `target` directory should be copied as an output
 , doCopyTargetToOutput ? true
   # Controls instructing rustc to remap the path prefix of any sources it
@@ -79,7 +76,6 @@ let
     inherit
       cargoArtifacts
       cargoVendorDir
-      doCompressTarget
       doCopyTargetToOutput
       doRemapSourcePathPrefix;
 

pkgs/copyCargoTargetToOutputHook.sh

@@ -4,18 +4,12 @@ copyCargoTargetToOutput() {
   export SOURCE_DATE_EPOCH=1
   mkdir -p "${target}"
 
-  if [ "1" != "${doCompressTarget-}" ]; then
-    # Copy the cargo `target` directory to the `target` output
-    mv "${CARGO_TARGET_DIR:-target}" "${target}/target"
-    return
-  fi
-
   # See: https://reproducible-builds.org/docs/archives/
   tar --sort=name \
     --mtime="@${SOURCE_DATE_EPOCH}" \
     --owner=0 --group=0 --numeric-owner \
     --pax-option=exthdr.name=%d/PaxHeaders/%f,delete=atime,delete=ctime \
-    -c target | @zstd@ -o "${target}/target.tar.zst"
+    -c "${CARGO_TARGET_DIR:-target}" | @zstd@ -o "${target}/target.tar.zst"
 }
 
 if [ "1" = "${doCopyTargetToOutput-}" ]; then

pkgs/default.nix

@@ -26,7 +26,6 @@
     {
       name = "inheritCargoArtifactsHook";
       substitutions = {
-        rsync = "${rsync}/bin/rsync";
         zstd = "${zstd}/bin/zstd";
       };
     } ./inheritCargoArtifactsHook.sh;

pkgs/inheritCargoArtifactsHook.sh

@@ -1,5 +1,5 @@
 inheritCargoArtifacts() {
-  echo "Executing inheritCargoArtifacts"
+  echo cargoArtifacts is ${cargoArtifacts}
 
   local cargoTarget="${CARGO_TARGET_DIR:-target}"
   mkdir -p "${cargoTarget}"
@@ -7,16 +7,6 @@ inheritCargoArtifacts() {
   if [ -f "${cargoArtifacts}/target.tar.zst" ]; then
     @zstd@ -d "${cargoArtifacts}/target.tar.zst" --stdout | \
       tar -x -C "${cargoTarget}" --strip-components=1
-  elif [ -d "${cargoArtifacts}/target" ]; then
-    @rsync@ \
-      --recursive \
-      --links \
-      --executability \
-      --chmod=+w \
-      --no-perms \
-      --no-owner \
-      --no-group \
-      "${cargoArtifacts}/target" "${cargoTarget}"
   else
     echo "${cargoArtifacts} looks invalid, are you sure it is pointing to a ".target" output?"
     false

tests/default.nix

@@ -27,6 +27,18 @@ pkgs.lib.makeScope myLib.newScope (self:
         "overlapping-targets"
       ]);
 
+    customCargoTargetDirectory = let
+      simple = myLib.buildWithCargo {
+        doCopyTargetToOutput = false;
+        src = ./simple;
+        CARGO_TARGET_DIR = "my-custom-cargo-dir";
+      };
+    in pkgs.runCommand "smoke-simple" { } ''
+      # does it run?
+      ${simple}/bin/simple
+      touch $out
+    '';
+
     smokeSimple = let
       simple = myLib.buildWithCargo {
         doCopyTargetToOutput = false;