Pre-build msg packages with micro-ROS typesupport before full build (#820)

Signed-off-by: David Laseca Perez <davidlaseca@eprosima.com>

Author: David-LP99

config/host/generic/build.sh

@@ -6,4 +6,25 @@ set +o nounset
 . install/local_setup.bash
 set -o nounset
 
+# Pre-build foundational message packages with the workspace microxrcedds type supports
+# already in the path.  These packages are implicit dependencies of many interface
+# packages (added by rosidl's action/service expansion), but are NOT declared in those
+# packages' package.xml files.  Without pre-building them in the workspace, cmake would
+# find the system /opt/ros/jazzy versions (which have no microxrcedds type support) and
+# the generated libraries would fail to link.
+#
+# Build order matters:
+#   builtin_interfaces      - no workspace deps
+#   unique_identifier_msgs  - no workspace deps (UUID.msg only)
+#   service_msgs            - depends on builtin_interfaces (ServiceEventInfo.msg)
+#   action_msgs             - depends on all three above; has CancelGoal.srv
+colcon build --packages-select builtin_interfaces unique_identifier_msgs service_msgs action_msgs --metas src --cmake-args -DBUILD_TESTING=OFF -DBUILD_SHARED_LIBS=ON $@
+
+# Re-source so the pre-built packages appear in CMAKE_PREFIX_PATH *before* the system
+# /opt/ros/jazzy path.  This ensures cmake prefers workspace versions (with microxrcedds
+# type support) when configuring packages in the full workspace build below.
+set +o nounset
+. install/local_setup.bash
+set -o nounset
+
 colcon build --metas src --cmake-args -DBUILD_TESTING=OFF -DBUILD_SHARED_LIBS=ON $@