Upstream fixed marisa 0.3.0 support by using C++17:
https://github.com/BYVoid/OpenCC/commit/2e9eb53c5e7124ee93ee2cb2225d839f99e4f7ed

Adjusted for 1.1.7 and 1.1.9, which still pass explicit -std=c++14 flags.

--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -72,7 +72,7 @@ include(CPack)
 
 if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
     set(CMAKE_MACOSX_RPATH 1)
-    set(CMAKE_CXX_STANDARD 14)
+    set(CMAKE_CXX_STANDARD 17)
     set(CMAKE_CXX_STANDARD_REQUIRED ON)
 endif()
 
@@ -154,7 +154,7 @@ add_definitions(
 
 if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
   add_definitions(
-    -std=c++14
+    -std=c++17
     -Wall
   )
   set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -pthread")
@@ -163,7 +163,7 @@ if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
   endif ()
 elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
   add_definitions(
-    -std=c++14
+    -std=c++17
     -Wall
   )
   set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -pthread")