Merge pull request #2751 from gangliao/fix_merge

FIX: propagation dependencies and rebuild out of date libs

cmake/generic.cmake

@@ -99,15 +99,33 @@ function(merge_static_libs TARGET_NAME)
   set(libs ${ARGN})
   list(REMOVE_DUPLICATES libs)
 
-  # First get the file names of the libraries to be merged
+  # Get all propagation dependencies from the merged libraries
   foreach(lib ${libs})
-    set(libfiles ${libfiles} $<TARGET_FILE:${lib}>)
+    list(APPEND libs_deps ${${lib}_LIB_DEPENDS})
   endforeach()
 
   if(APPLE) # Use OSX's libtool to merge archives
+    # To produce a library we need at least one source file.
+    # It is created by add_custom_command below and will helps 
+    # also help to track dependencies.
     set(dummyfile ${CMAKE_CURRENT_BINARY_DIR}/${TARGET_NAME}_dummy.c)
+
+    # Make the generated dummy source file depended on all static input
+    # libs. If input lib changes,the source file is touched
+    # which causes the desired effect (relink).
+    add_custom_command(OUTPUT ${dummyfile}
+      COMMAND ${CMAKE_COMMAND} -E touch ${dummyfile}
+      DEPENDS ${libs})
+
+    # Generate dummy staic lib
     file(WRITE ${dummyfile} "const char * dummy = \"${dummyfile}\";")
     add_library(${TARGET_NAME} STATIC ${dummyfile})
+    target_link_libraries(${TARGET_NAME} ${libs_deps})
+
+    foreach(lib ${libs})
+      # Get the file names of the libraries to be merged
+      set(libfiles ${libfiles} $<TARGET_FILE:${lib}>)
+    endforeach()
 		add_custom_command(TARGET ${TARGET_NAME} POST_BUILD
       COMMAND rm "${CMAKE_CURRENT_BINARY_DIR}/lib${TARGET_NAME}.a"
       COMMAND /usr/bin/libtool -static -o "${CMAKE_CURRENT_BINARY_DIR}/lib${TARGET_NAME}.a" ${libfiles})
@@ -117,7 +135,8 @@ function(merge_static_libs TARGET_NAME)
       set(objdir ${lib}.objdir)
 
       add_custom_command(OUTPUT ${objdir}
-        COMMAND ${CMAKE_COMMAND} -E make_directory ${objdir})
+        COMMAND ${CMAKE_COMMAND} -E make_directory ${objdir}
+        DEPENDS ${lib})
 
       add_custom_command(OUTPUT ${objlistfile}
         COMMAND ${CMAKE_AR} -x "$<TARGET_FILE:${lib}>"
@@ -134,18 +153,18 @@ function(merge_static_libs TARGET_NAME)
       list(APPEND mergebases "${mergebase}")
     endforeach()
 
-    # We need a target for the output merged library
     add_library(${TARGET_NAME} STATIC ${mergebases})
+    target_link_libraries(${TARGET_NAME} ${libs_deps}) 
+
+    # Get the file name of the generated library
     set(outlibfile "$<TARGET_FILE:${TARGET_NAME}>")
 
     foreach(lib ${libs})
       add_custom_command(TARGET ${TARGET_NAME} POST_BUILD
-      COMMAND ${CMAKE_AR} ru ${outlibfile} @"../${lib}.objlist"
+        COMMAND ${CMAKE_AR} cr ${outlibfile} *.o  
+        COMMAND ${CMAKE_RANLIB} ${outlibfile}
         WORKING_DIRECTORY ${lib}.objdir)
     endforeach()
-
-    add_custom_command(TARGET ${TARGET_NAME} POST_BUILD
-      COMMAND ${CMAKE_RANLIB} ${outlibfile})
   endif()
 endfunction(merge_static_libs)