Fixes for Xenial. (#103)

- Remove use of get_property(LOCATION in cmake where this is easy. This
  reduces build warnings sufficiently to not drown out other important
  information.
- Mark cairo a dependency in package.xml so rosdep pulls it in.

Tested using docker -t ros:kinetic, which is based on Xenial.

CMakeLists.txt

@@ -70,6 +70,12 @@ google_combined_library(cartographer
   SRCS "${ALL_LIBRARIES}"
 )
 
+# TODO(hrapp): Replacing this get_property with a generator expression is not
+# very easy: it needs to be expanded into a variable which is then used for
+# CONFIGURE_PACKAGE_CONFIG_FILE - I did not find an easy way to do it. A
+# complicated way is to file(READ the cartographer-config.cmake.in and
+# string(CONFIGURE it, then file(GENERATE the output file. I do not have the
+# stomach to attempt this right now.
 get_property(CARTOGRAPHER_LIBRARY_FILE TARGET cartographer PROPERTY LOCATION)
 get_filename_component(CARTOGRAPHER_LIBRARY_FILE_BASENAME
   ${CARTOGRAPHER_LIBRARY_FILE} NAME)

cmake/functions.cmake

@@ -21,7 +21,6 @@ macro(_parse_arguments ARGS)
     USES_EIGEN
     USES_GFLAGS
     USES_GLOG
-    USES_GLOG
     USES_LUA
     USES_WEBP
     USES_CAIRO
@@ -179,25 +178,22 @@ function(google_combined_library NAME)
     DEPENDS ${ARG_SRCS}
   )
 
-  get_property(OUTPUT_FILE TARGET ${NAME} PROPERTY LOCATION)
-
   # We will delete the static lib generated by the last call to
   # 'google_library' and recreate it using a GNU ar script that combines the
   # SRCS into the NAME.
   # TODO(hrapp): this is probably not very portable, but should work fine on
   # Linux.
   set(AR_SCRIPT "")
-  set(AR_SCRIPT "CREATE ${OUTPUT_FILE}\n")
+  set(AR_SCRIPT "CREATE $<TARGET_FILE:${NAME}>\n")
   foreach(SRC ${ARG_SRCS})
-    get_property(STATIC_LIBRARY_FILE TARGET ${SRC} PROPERTY LOCATION)
-    set(AR_SCRIPT "${AR_SCRIPT}ADDLIB ${STATIC_LIBRARY_FILE}\n")
+    set(AR_SCRIPT "${AR_SCRIPT}ADDLIB $<TARGET_FILE:${SRC}>\n")
   endforeach()
   set(AR_SCRIPT "${AR_SCRIPT}SAVE\nEND\n")
   set(AR_SCRIPT_FILE "${CMAKE_CURRENT_BINARY_DIR}/${NAME}_ar.script")
-  file(WRITE ${AR_SCRIPT_FILE} ${AR_SCRIPT})
+  file(GENERATE OUTPUT ${AR_SCRIPT_FILE} CONTENT ${AR_SCRIPT})
 
   add_custom_command(TARGET ${NAME} POST_BUILD
-    COMMAND rm ${OUTPUT_FILE}
+    COMMAND rm $<TARGET_FILE:${NAME}>
     COMMAND ${CMAKE_AR}
     ARGS -M < ${AR_SCRIPT_FILE}
     COMMENT "Recombining static libraries into ${NAME}."

package.xml

@@ -39,6 +39,7 @@
   <depend>boost</depend>
   <depend>ceres_solver</depend>
   <depend>eigen</depend>
+  <depend>libcairo2-dev</depend>
   <depend>libgflags-dev</depend>
   <depend>libgoogle-glog-dev</depend>
   <depend>libwebp-dev</depend>