From 20ae88228d9fbc0f3ee87c7694fb9429dfb000cc Mon Sep 17 00:00:00 2001
From: Michal Sojka <michal.sojka@cvut.cz>
Date: Sat, 19 Apr 2025 07:17:48 +0200
Subject: [PATCH] Remove dev outputs in ament-cmake-core and
 python-cmake-module

These dev outputs prevent building of ROS packages with colcon inside
buildEnv unless ament-colcon-core and python-cmake-module are
explicitly installed. Specifically, if one installs only dependencies
declared in package.xml, e.g., ament_cmake, the build fails because
cmake complains about not finding ament_cmake_core.

As far as I understand, the reason is that buildEnv recursively
includes all propagatedBuildInputs but uses their dev outputs if they
exist. In case of the mentioned packages, these outputs are empty
except nix-support/propagated-build-inputs. This file correctly
propagates the "out" output of the same package, but this is not
(by design) reflected inside buildEnv.

This change fixes the above problem and seems not to cause any new
build failure in the overlay. This was verified by Hydra:
https://hydra.iid.ciirc.cvut.cz/eval/3868?compare=lopsided98-develop&full=0.

The problem described above can be reproduced by the following
sequence of commands:

    git clone https://github.com/ros2/demos -b jazzy
    cd demos/demo_nodes_cpp
    cat > shell.nix <<'EOF'
    {
      nix-ros-overlay ? builtins.fetchTarball "https://github.com/lopsided98/nix-ros-overlay/archive/master.tar.gz",
      pkgs ? import nix-ros-overlay { },
      rosDistro ? "jazzy",
    }:
    pkgs.mkShell {
      name = "ros2nix ${rosDistro} shell";
      packages = [
        (pkgs.rosPackages.${rosDistro}.buildEnv {
          wrapPrograms = false;
          paths =
            [
              pkgs.colcon
              pkgs.rosPackages.${rosDistro}.ros-core
            ]
            ++ (
              with pkgs;
              with pkgs.rosPackages.${rosDistro};
              [
                ament-cmake
                example-interfaces
                launch-ros
                launch-xml
                rcl
                rcl-interfaces
                rclcpp
                rclcpp-components
                rcpputils
                rcutils
                rmw
                std-msgs
              ]
            );
          }
        )
      ];
    }
    EOF
    nix-shell
    colcon build

If one enters the shell as:

    nix-shell --arg nix-ros-overlay /path/to/this/pr

then `colcon build` succeeds.
---
 distros/ros2-overlay.nix | 2 --
 1 file changed, 2 deletions(-)

diff --git a/distros/ros2-overlay.nix b/distros/ros2-overlay.nix
index 9ed545629d..110ba0c0fa 100644
--- a/distros/ros2-overlay.nix
+++ b/distros/ros2-overlay.nix
@@ -13,7 +13,6 @@ rosSelf: rosSuper: with rosSelf.lib; {
   in {
     propagatedBuildInputs = [ setupHook ] ++ propagatedBuildInputs;
     nativeBuildInputs = [ setupHook ] ++ nativeBuildInputs;
-    outputs = [ "out" "dev" ];
   });
 
   ament-cmake-vendor-package = rosSuper.ament-cmake-vendor-package.overrideAttrs ({
@@ -183,7 +182,6 @@ rosSelf: rosSuper: with rosSelf.lib; {
     pythonLibrary = "${python}/lib/lib${python.libPrefix}${libExt}";
     pythonIncludeDir = "${python}/include/${python.libPrefix}";
     setupHook = ./python-cmake-module-setup-hook.sh;
-    outputs = [ "out" "dev" ];
   });
 
   rcutils = rosSuper.rcutils.overrideAttrs ({