Set version in one place

CMakeLists.txt

@@ -126,11 +126,14 @@ if (FMT_TEST)
   add_subdirectory(test)
 endif ()
 
-set(CPACK_PACKAGE_VERSION_MAJOR 1)
-set(CPACK_PACKAGE_VERSION_MINOR 2)
-set(CPACK_PACKAGE_VERSION_PATCH 0)
-set(CPPFORMAT_VERSION
-  ${CPACK_PACKAGE_VERSION_MAJOR}.${CPACK_PACKAGE_VERSION_MINOR}.${CPACK_PACKAGE_VERSION_PATCH})
+set(CPPFORMAT_VERSION 1.2.0)
+if (NOT CPPFORMAT_VERSION MATCHES "^([0-9]+).([0-9]+).([0-9]+)$")
+  message(FATAL_ERROR "Invalid version format ${CPPFORMAT_VERSION}.")
+endif ()
+set(CPACK_PACKAGE_VERSION_MAJOR ${CMAKE_MATCH_1})
+set(CPACK_PACKAGE_VERSION_MINOR ${CMAKE_MATCH_2})
+set(CPACK_PACKAGE_VERSION_PATCH ${CMAKE_MATCH_3})
+
 set_target_properties(cppformat PROPERTIES
   VERSION ${CPPFORMAT_VERSION} SOVERSION ${CPACK_PACKAGE_VERSION_MAJOR})