Prefer pkg-config over CMake not to lose version checking

Signed-off-by: Jose Luis Rivero <[email protected]>

cmake/FindIgnURDFDOM.cmake

@@ -14,32 +14,39 @@
 # limitations under the License.
 #
 
-if (IgnURDFDOM_FIND_VERSION)
+if(IgnURDFDOM_FIND_VERSION)
   set(find_version VERSION ${IgnURDFDOM_FIND_VERSION})
 else()
   set(find_version "")
 endif()
-# NOTE: urdfdom cmake does not support version checking
-ign_find_package(urdfdom ${find_version} QUIET)
 
-if (urdfdom_FOUND)
-  add_library(IgnURDFDOM::IgnURDFDOM INTERFACE IMPORTED)
-  target_link_libraries(IgnURDFDOM::IgnURDFDOM
-    INTERFACE
-      urdfdom::urdfdom_model
-      urdfdom::urdfdom_world
-      urdfdom::urdfdom_sensor
-      urdfdom::urdfdom_model_state
-  )
-  include(FindPackageHandleStandardArgs)
-  find_package_handle_standard_args(IgnURDFDOM DEFAULT_MSG)
-else()
-  message(VERBOSE "unable to find urdf cmake package, trying pkgconfig...")
-  include(IgnPkgConfig)
+# Prefer pkg-config over cmake if possible since version checking is not working
+# on urdfdom series from 1.x to 3.0.0 (at least)
+include(IgnPkgConfig)
+if (NOT PKG_CONFIG_FOUND)
   if (IgnURDFDOM_FIND_VERSION)
     set(signature "urdfdom >= ${IgnURDFDOM_FIND_VERSION}")
   else()
     set(signature "urdfdom")
   endif()
   ign_pkg_check_modules(IgnURDFDOM "${signature}")
+else()
+  message(VERBOSE "Unable to find pkg-config in the system, fallback to use CMake")
+endif()
+
+if(NOT IgnURDFDOM_FOUND)
+  # NOTE: urdfdom cmake does not support version checking
+  ign_find_package(urdfdom ${find_version} QUIET)
+  if (urdfdom_FOUND)
+    add_library(IgnURDFDOM::IgnURDFDOM INTERFACE IMPORTED)
+    target_link_libraries(IgnURDFDOM::IgnURDFDOM
+      INTERFACE
+        urdfdom::urdfdom_model
+        urdfdom::urdfdom_world
+        urdfdom::urdfdom_sensor
+        urdfdom::urdfdom_model_state
+    )
+    include(FindPackageHandleStandardArgs)
+    find_package_handle_standard_args(IgnURDFDOM DEFAULT_MSG)
+  endif()
 endif()