Generate counterexamples for conflicts (if bison version is at least 3.7.0)

CMakeConf.cmake

@@ -115,7 +115,11 @@ function(FLEX_BISON_SOURCE TARGET LEXFNAME YFNAME LEXCPP YCPP YHPP)
 	get_filename_component(YFNAME_PATH "${YFNAME}" ABSOLUTE) 
 
 	FLEX_TARGET("${LEXCPP}" "${LEXFNAME_PATH}" "${CMAKE_CURRENT_BINARY_DIR}/${LEXCPP}")
-	BISON_TARGET("${YCPP}" "${YFNAME_PATH}" "${CMAKE_CURRENT_BINARY_DIR}/${YCPP}" DEFINES_FILE "${CMAKE_CURRENT_BINARY_DIR}/${YHPP}" VERBOSE REPORT_FILE "${CMAKE_CURRENT_BINARY_DIR}/${YFNAME}.output")
+	if("${BISON_VERSION}" VERSION_GREATER_EQUAL "3.7.0")
+		BISON_TARGET("${YCPP}" "${YFNAME_PATH}" "${CMAKE_CURRENT_BINARY_DIR}/${YCPP}" COMPILE_FLAGS "-Wcounterexamples" DEFINES_FILE "${CMAKE_CURRENT_BINARY_DIR}/${YHPP}" VERBOSE REPORT_FILE "${CMAKE_CURRENT_BINARY_DIR}/${YFNAME}.output")
+	else()
+		BISON_TARGET("${YCPP}" "${YFNAME_PATH}" "${CMAKE_CURRENT_BINARY_DIR}/${YCPP}" DEFINES_FILE "${CMAKE_CURRENT_BINARY_DIR}/${YHPP}" VERBOSE REPORT_FILE "${CMAKE_CURRENT_BINARY_DIR}/${YFNAME}.output")
+	endif()
 	ADD_FLEX_BISON_DEPENDENCY("${LEXCPP}" "${YCPP}")
 
 	DEFINE_FLEX_SOURCE("${TARGET}" "${LEXFNAME}" "${LEXCPP}" "${YHPP}")