Compile error for cpp-pinyin c++17

[alps2006]

compile error for std::filesystem that provided in c++17.

In file included from pinyin.cc:33:
/usr/local/include/cpp-pinyin/G2pglobal.h:10:10: error: no member named 'filesystem' in namespace 'std'
    std::filesystem::path CPP_PINYIN_EXPORT dictionaryPath();
    ~~~~~^
/usr/local/include/cpp-pinyin/G2pglobal.h:12:57: error: no member named 'filesystem' in namespace 'std'
    void CPP_PINYIN_EXPORT setDictionaryPath(const std::filesystem::path &dir);
                                                   ~~~~~^

After making pinyin-completion to compile with c++17, the error is arisen below.

pinyin-completion/module/Src/zi/pinyin.so, 0x0009): symbol not found in flat namespace '__ZN6Pinyin7ManTone10toneToToneERKNSt3__112basic_stringIDsNS1_11char_traitsIDsEENS1_9allocatorIDsEEEEbb'