Add rosidl_find_package_idl helper function

rosidl_cmake/cmake/rosidl_find_package_idl.cmake

@@ -0,0 +1,43 @@
+# Copyright 2023 Open Source Robotics Foundation, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Get the absolute path of an IDL file stored in a package's share
+# directory, checking if the package's find module set a GNUInstallDirs
+# pkgname_DATADIR variable pointing to a separate location from the
+# default pkgname_DIR.
+#
+# :param var: A name of a variable to store the idl file absolute path.
+# :param pkg_name: Name of the package, assumed to have already been
+#   find_package'd.
+# :type pkg_name: string
+# :param idl_name: The filename of the idl file to look for.
+# :type idl_name: string
+#
+# @public
+#
+function(rosidl_find_package_idl var pkg_name idl_file)
+  set(_candidates
+    "${${pkg_name}_DATADIR}/${idl_file}"
+    "${${pkg_name}_DIR}/../${idl_file}"
+  )
+  foreach(_try ${_candidates})
+    if(EXISTS "${_try}")
+      normalize_path(_norm "${_try}")
+      set("${var}" "${_norm}" PARENT_SCOPE)
+      return()
+    endif()
+  endforeach()
+  message(FATAL_ERROR "Unable to find ${idl_file} in any of ${_candidates} for ${pkg_name}.")
+  set("${var}" "-NOTFOUND" PARENT_SCOPE)
+endfunction()

rosidl_cmake/cmake/rosidl_generate_interfaces.cmake

@@ -193,8 +193,7 @@ macro(rosidl_generate_interfaces target)
         "'${_dep}' has not been found before using find_package()")
     endif()
     foreach(_idl_file ${${_dep}_IDL_FILES})
-      set(_abs_idl_file "${${_dep}_DIR}/../${_idl_file}")
-      normalize_path(_abs_idl_file "${_abs_idl_file}")
+      rosidl_find_package_idl(_abs_idl_file "${_dep}" "${_idl_file}")
       list(APPEND _dep_files "${_abs_idl_file}")
     endforeach()
   endforeach()

rosidl_cmake/rosidl_cmake-extras.cmake

@@ -58,3 +58,4 @@ endmacro()
 
 include("${rosidl_cmake_DIR}/rosidl_export_typesupport_libraries.cmake")
 include("${rosidl_cmake_DIR}/rosidl_export_typesupport_targets.cmake")
+include("${rosidl_cmake_DIR}/rosidl_find_package_idl.cmake")

rosidl_generator_c/cmake/rosidl_generator_c_generate_interfaces.cmake

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 find_package(rcutils REQUIRED)
+find_package(rosidl_cmake REQUIRED)
 find_package(rosidl_runtime_c REQUIRED)
 find_package(rosidl_typesupport_interface REQUIRED)
 
@@ -43,8 +44,7 @@ set(_dependency_files "")
 set(_dependencies "")
 foreach(_pkg_name ${rosidl_generate_interfaces_DEPENDENCY_PACKAGE_NAMES})
   foreach(_idl_file ${${_pkg_name}_IDL_FILES})
-    set(_abs_idl_file "${${_pkg_name}_DIR}/../${_idl_file}")
-    normalize_path(_abs_idl_file "${_abs_idl_file}")
+    rosidl_find_package_idl(_abs_idl_file "${_pkg_name}" "${_idl_file}")
     list(APPEND _dependency_files "${_abs_idl_file}")
     list(APPEND _dependencies "${_pkg_name}:${_abs_idl_file}")
   endforeach()

rosidl_generator_c/package.xml

@@ -24,6 +24,7 @@
   <buildtool_export_depend>python3</buildtool_export_depend>
   <buildtool_export_depend>rosidl_pycommon</buildtool_export_depend>
 
+  <build_export_depend>rosidl_cmake</build_export_depend>
   <build_export_depend>rosidl_generator_type_description</build_export_depend>
   <build_export_depend>rosidl_typesupport_interface</build_export_depend>
   <build_export_depend>rcutils</build_export_depend>

rosidl_generator_cpp/cmake/rosidl_generator_cpp_generate_interfaces.cmake

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+find_package(rosidl_cmake REQUIRED)
 find_package(rosidl_runtime_cpp REQUIRED)
 
 set(_output_path
@@ -36,8 +37,7 @@ set(_dependency_files "")
 set(_dependencies "")
 foreach(_pkg_name ${rosidl_generate_interfaces_DEPENDENCY_PACKAGE_NAMES})
   foreach(_idl_file ${${_pkg_name}_IDL_FILES})
-    set(_abs_idl_file "${${_pkg_name}_DIR}/../${_idl_file}")
-    normalize_path(_abs_idl_file "${_abs_idl_file}")
+    rosidl_find_package_idl(_abs_idl_file "${_pkg_name}" "${_idl_file}")
     list(APPEND _dependency_files "${_abs_idl_file}")
     list(APPEND _dependencies "${_pkg_name}:${_abs_idl_file}")
   endforeach()

rosidl_generator_cpp/package.xml

@@ -22,6 +22,7 @@
   <buildtool_export_depend>python3</buildtool_export_depend>
   <buildtool_export_depend>rosidl_pycommon</buildtool_export_depend>
 
+  <build_export_depend>rosidl_cmake</build_export_depend>
   <!-- This is needed for the rosidl_message_type_support_t struct and visibility macros -->
   <build_export_depend>rosidl_generator_c</build_export_depend>
   <build_export_depend>rosidl_runtime_cpp</build_export_depend>

rosidl_typesupport_introspection_c/cmake/rosidl_typesupport_introspection_c_generate_interfaces.cmake

@@ -18,6 +18,7 @@ if(NOT TARGET ${rosidl_generate_interfaces_TARGET}__rosidl_generator_c)
     "'rosidl_typesupport_introspection_c' extension.")
 endif()
 
+find_package(rosidl_cmake REQUIRED)
 find_package(rosidl_runtime_c REQUIRED)
 find_package(rosidl_typesupport_interface REQUIRED)
 find_package(rosidl_typesupport_introspection_c REQUIRED)
@@ -41,8 +42,7 @@ set(_dependency_files "")
 set(_dependencies "")
 foreach(_pkg_name ${rosidl_generate_interfaces_DEPENDENCY_PACKAGE_NAMES})
   foreach(_idl_file ${${_pkg_name}_IDL_FILES})
-    set(_abs_idl_file "${${_pkg_name}_DIR}/../${_idl_file}")
-    normalize_path(_abs_idl_file "${_abs_idl_file}")
+    rosidl_find_package_idl(_abs_idl_file "${_pkg_name}" "${_idl_file}")
     list(APPEND _dependency_files "${_abs_idl_file}")
     list(APPEND _dependencies "${_pkg_name}:${_abs_idl_file}")
   endforeach()

rosidl_typesupport_introspection_c/package.xml

@@ -25,6 +25,7 @@
   <buildtool_export_depend>rosidl_generator_c</buildtool_export_depend>
   <buildtool_export_depend>rosidl_pycommon</buildtool_export_depend>
 
+  <build_export_depend>rosidl_cmake</build_export_depend>
   <build_export_depend>rosidl_runtime_c</build_export_depend>
   <build_export_depend>rosidl_typesupport_interface</build_export_depend>
 

rosidl_typesupport_introspection_cpp/cmake/rosidl_typesupport_introspection_cpp_generate_interfaces.cmake

@@ -18,6 +18,7 @@ if(NOT TARGET ${rosidl_generate_interfaces_TARGET}__rosidl_generator_cpp)
     "'rosidl_typesupport_introspection_cpp' extension.")
 endif()
 
+find_package(rosidl_cmake REQUIRED)
 find_package(rosidl_runtime_c REQUIRED)
 find_package(rosidl_typesupport_interface REQUIRED)
 find_package(rosidl_typesupport_introspection_cpp REQUIRED)
@@ -41,8 +42,7 @@ set(_dependency_files "")
 set(_dependencies "")
 foreach(_pkg_name ${rosidl_generate_interfaces_DEPENDENCY_PACKAGE_NAMES})
   foreach(_idl_file ${${_pkg_name}_IDL_FILES})
-    set(_abs_idl_file "${${_pkg_name}_DIR}/../${_idl_file}")
-    normalize_path(_abs_idl_file "${_abs_idl_file}")
+    rosidl_find_package_idl(_abs_idl_file "${_pkg_name}" "${_idl_file}")
     list(APPEND _dependency_files "${_abs_idl_file}")
     list(APPEND _dependencies "${_pkg_name}:${_abs_idl_file}")
   endforeach()

rosidl_typesupport_introspection_cpp/package.xml

@@ -26,6 +26,7 @@
   <buildtool_export_depend>rosidl_generator_cpp</buildtool_export_depend>
   <buildtool_export_depend>rosidl_pycommon</buildtool_export_depend>
 
+  <build_export_depend>rosidl_cmake</build_export_depend>
   <build_export_depend>rosidl_runtime_c</build_export_depend>
   <build_export_depend>rosidl_runtime_cpp</build_export_depend>