/in/foo.cc:39:13: warning: #pragma system_header ignored outside include file
 #pragma GCC system_header
             ^~~~~~~~~~~~~
/in/foo.cc:73:51: error: expected initializer before 'norm'
   template<typename _Tp> _Tp _GLIBCXX20_CONSTEXPR norm(const complex<_Tp>&);
                                                   ^~~~
/in/foo.cc:77:5: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     _GLIBCXX20_CONSTEXPR complex<_Tp> conj(const complex<_Tp>&);
     ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:173:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR void
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:176:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR void
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:180:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR complex<_Tp>& operator=(const _Tp&);
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:184:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR complex<_Tp>&
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:193:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR complex<_Tp>&
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:201:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR complex<_Tp>& operator*=(const _Tp&);
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:203:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR complex<_Tp>& operator/=(const _Tp&);
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:207:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR complex& operator=(const complex&) = default;
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:212:9: error: '_GLIBCXX20_CONSTEXPR' does not name a type
         _GLIBCXX20_CONSTEXPR complex<_Tp>& operator=(const complex<_Up>&);
         ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:215:9: error: '_GLIBCXX20_CONSTEXPR' does not name a type
         _GLIBCXX20_CONSTEXPR complex<_Tp>& operator+=(const complex<_Up>&);
         ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:218:9: error: '_GLIBCXX20_CONSTEXPR' does not name a type
         _GLIBCXX20_CONSTEXPR complex<_Tp>& operator-=(const complex<_Up>&);
         ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:221:9: error: '_GLIBCXX20_CONSTEXPR' does not name a type
         _GLIBCXX20_CONSTEXPR complex<_Tp>& operator*=(const complex<_Up>&);
         ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:224:9: error: '_GLIBCXX20_CONSTEXPR' does not name a type
         _GLIBCXX20_CONSTEXPR complex<_Tp>& operator/=(const complex<_Up>&);
         ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:235:5: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     _GLIBCXX20_CONSTEXPR complex<_Tp>&
     ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:245:5: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     _GLIBCXX20_CONSTEXPR complex<_Tp>&
     ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:255:5: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     _GLIBCXX20_CONSTEXPR complex<_Tp>&
     ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:265:5: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     _GLIBCXX20_CONSTEXPR complex<_Tp>&
     ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:276:5: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     _GLIBCXX20_CONSTEXPR complex<_Tp>&
     ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:287:5: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     _GLIBCXX20_CONSTEXPR complex<_Tp>&
     ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:299:5: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     _GLIBCXX20_CONSTEXPR complex<_Tp>&
     ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:312:5: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     _GLIBCXX20_CONSTEXPR complex<_Tp>&
     ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:326:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:335:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:344:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:356:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:365:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:374:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:386:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:395:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:404:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:416:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:425:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:434:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:445:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:451:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:662:23: error: '_GLIBCXX20_CONSTEXPR' does not name a type
         static inline _GLIBCXX20_CONSTEXPR _Tp _S_do_it(const complex<_Tp>& __z)
                       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:674:23: error: '_GLIBCXX20_CONSTEXPR' does not name a type
         static inline _GLIBCXX20_CONSTEXPR _Tp _S_do_it(const complex<_Tp>& __z)
                       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:685:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR _Tp
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:701:12: error: '_GLIBCXX20_CONSTEXPR' does not name a type
     inline _GLIBCXX20_CONSTEXPR complex<_Tp>
            ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1122:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR void
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1125:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR void
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1128:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR complex&
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1135:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR complex&
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1142:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR complex&
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1149:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR complex&
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1156:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR complex&
       ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1170:9: error: '_GLIBCXX20_CONSTEXPR' does not name a type
         _GLIBCXX20_CONSTEXPR complex&
         ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1179:9: error: '_GLIBCXX20_CONSTEXPR' does not name a type
         _GLIBCXX20_CONSTEXPR complex&
         ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1187:9: error: '_GLIBCXX20_CONSTEXPR' does not name a type
         _GLIBCXX20_CONSTEXPR complex&
         ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1195:9: error: '_GLIBCXX20_CONSTEXPR' does not name a type
         _GLIBCXX20_CONSTEXPR complex&
         ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1204:9: error: '_GLIBCXX20_CONSTEXPR' does not name a type
         _GLIBCXX20_CONSTEXPR complex&
         ^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:1269:7: error: '_GLIBCXX20_CONSTEXPR' does not name a type
       _GLIBCXX20_CONSTEXPR