cgi3.2.9 make install 在 ubuntu 18.4 中失败

Question

当我安装 cgi 3.2.9 时，它列出了以下错误：

Making install in cgicc make[1]: Entering directory
'/root/learncpp/webprogramming/cgicc-3.2.9/cgicc' /bin/bash
../libtool  --tag=CXX   --mode=compile g++ -DHAVE_CONFIG_H -I. -I..
-I.. -x c++    -Wall -W -pedantic -g -O2 -MT libcgicc_la-Cgicc.lo -MD -MP -MF .deps/libcgicc_la-Cgicc.Tpo -c -o libcgicc_la-Cgicc.lo `test -f 'Cgicc.cpp' || echo './'`Cgicc.cpp libtool: compile:  g++
-DHAVE_CONFIG_H -I. -I.. -I.. -x c++ -Wall -W -pedantic -g -O2 -MT libcgicc_la-Cgicc.lo -MD -MP -MF .deps/libcgicc_la-Cgicc.Tpo -c
Cgicc.cpp  -fPIC -DPIC -o .libs/libcgicc_la-Cgicc.o Cgicc.cpp: In
member function ‘bool cgicc::Cgicc::findEntries(const string&, bool,
std::vector<cgicc::FormEntry>&) const’: Cgicc.cpp:328:54: error:
call of overloaded
‘copy_if(std::vector<cgicc::FormEntry>::const_iterator,
std::vector<cgicc::FormEntry>::const_iterator,
std::back_insert_iterator<std::vector<cgicc::FormEntry> >,
cgicc::FE_nameCompare)’ is ambiguous
      std::back_inserter(result),FE_nameCompare(param));
                                                      ^ Cgicc.cpp:99:3: note: candidate: Out cgicc::copy_if(In, In, Out,
Pred) [with In = __gnu_cxx::__normal_iterator<const
cgicc::FormEntry*, std::vector<cgicc::FormEntry> >; Out =
std::back_insert_iterator<std::vector<cgicc::FormEntry> >; Pred =
cgicc::FE_nameCompare]    copy_if(In first,    ^~~~~~~ In file
included from /usr/include/c++/7/algorithm:62:0,
                 from Cgicc.cpp:29: /usr/include/c++/7/bits/stl_algo.h:737:5: note: candidate: _OIter
std::copy_if(_IIter, _IIter, _OIter, _Predicate) [with _IIter =
__gnu_cxx::__normal_iterator<const cgicc::FormEntry*, std::vector<cgicc::FormEntry> >; _OIter =
std::back_insert_iterator<std::vector<cgicc::FormEntry> >;
_Predicate = cgicc::FE_nameCompare]
     copy_if(_InputIterator __first, _InputIterator __last,
     ^~~~~~~ Cgicc.cpp:332:56: error: call of overloaded ‘copy_if(std::vector<cgicc::FormEntry>::const_iterator,
std::vector<cgicc::FormEntry>::const_iterator,
std::back_insert_iterator<std::vector<cgicc::FormEntry> >,
cgicc::FE_valueCompare)’ is ambiguous
      std::back_inserter(result), FE_valueCompare(param));
                                                        ^ Cgicc.cpp:99:3: note: candidate: Out cgicc::copy_if(In, In, Out,
Pred) [with In = __gnu_cxx::__normal_iterator<const
cgicc::FormEntry*, std::vector<cgicc::FormEntry> >; Out =
std::back_insert_iterator<std::vector<cgicc::FormEntry> >; Pred =
cgicc::FE_valueCompare]    copy_if(In first,    ^~~~~~~ In file
included from /usr/include/c++/7/algorithm:62:0,
                 from Cgicc.cpp:29: /usr/include/c++/7/bits/stl_algo.h:737:5: note: candidate: _OIter
std::copy_if(_IIter, _IIter, _OIter, _Predicate) [with _IIter =
__gnu_cxx::__normal_iterator<const cgicc::FormEntry*, std::vector<cgicc::FormEntry> >; _OIter =
std::back_insert_iterator<std::vector<cgicc::FormEntry> >;
_Predicate = cgicc::FE_valueCompare]
     copy_if(_InputIterator __first, _InputIterator __last,
     ^~~~~~~ Makefile:417: recipe for target 'libcgicc_la-Cgicc.lo' failed make[1]: *** [libcgicc_la-Cgicc.lo] Error 1 make[1]: Leaving
directory '/root/learncpp/webprogramming/cgicc-3.2.9/cgicc'
Makefile:337: recipe for target 'install-recursive' failed make: ***
[install-recursive] Error 1

Answer 1

在使用 gcc 版本 7.3.0 (Ubuntu 7.3.0-27ubuntu1~18.04) 编译 cgicc 3.2.9 时，我遇到了同样的错误

copy_if 模板是在 C++ 11 及更高版本中定义的，所以我使用以下内容来防止 Cgicc.cpp 中的代码在已经被支持的情况下被编译：

#if __cplusplus <= 199711L
  // ============================================================
  // Function copy_if (handy, missing from STL)
  // ============================================================
  // This code taken directly from 
  // "The C++ Programming Language, Third Edition" by Bjarne Stroustrup
  template<class In, class Out, class Pred>
  Out 
  copy_if(In first, 
      In last, 
      Out res, 
      Pred p)
  {
    while(first != last) {
      if(p(*first))
    *res++ = *first;
      ++first;
    }
    return res;
  }
#endif

现在可以正常使用了。