[C++] Add dependencies to the custom command that generates IR codecs.

Without the dependency, CMake runs this command at every build which leads to unnecessary recompilation of dummy.cpp.

Author: denizevrenci

sbe-tool/src/main/cpp/CMakeLists.txt

@@ -14,17 +14,43 @@
 # limitations under the License.
 #
 
+file(GLOB_RECURSE CODECS
+ "uk_co_real_logic_sbe_ir_generated/*.h"
+)
+
 find_package(Java REQUIRED)
 
-add_custom_target(
- ir_codecs
+if(NOT(CODECS))
+ execute_process(
+ COMMAND
+ ${Java_JAVA_EXECUTABLE}
+ "-Dsbe.output.dir=${CMAKE_CURRENT_SOURCE_DIR}"
+ "-Dsbe.target.language=CPP"
+ "-jar" "${SBE_JAR}"
+ "../resources/sbe-ir.xml"
+ WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+ )
+
+ file(GLOB_RECURSE CODECS
+ "uk_co_real_logic_sbe_ir_generated/*.h"
+ )
+endif()
+
+add_custom_command(OUTPUT ${CODECS}
+ COMMAND
  ${Java_JAVA_EXECUTABLE}
  "-Dsbe.output.dir=${CMAKE_CURRENT_SOURCE_DIR}"
  "-Dsbe.target.language=CPP"
  "-jar" "${SBE_JAR}"
  "../resources/sbe-ir.xml"
- WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
- COMMENT "Generate IR codecs"
+ DEPENDS ${SBE_JAR} sbe-jar "../resources/sbe-ir.xml"
+ WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+ COMMENT "Generate IR codecs"
+)
+
+add_custom_target(
+ ir_codecs
+ DEPENDS ${CODECS}
 )
 
 set(HEADERS