[Bug c++/81992] New: C++ toupper symbol clash?

[jg at jguk dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81992

            Bug ID: 81992
           Summary: C++ toupper symbol clash?
           Product: gcc
           Version: 5.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jg at jguk dot org
  Target Milestone: ---

I thought functions can have the same name, because params are different in C++

eg my
void tolower(std::string & str)

If I rename my function to tolowerstr, it then works.

But I get a build error. I had expected not to conflict

int toupper( int ch );
http://en.cppreference.com/w/cpp/string/byte/toupper


$ g++ -O2 -Wall -Wextra -Wpedantic -o main main.cpp
main.cpp: In function ‘void tolower(std::__cxx11::string&)’:
main.cpp:23:66: error: no matching function for call to
‘transform(std::__cxx11::basic_string<char>::iterator,
std::__cxx11::basic_string<char>::iterator,
std::__cxx11::basic_string<char>::iterator, <unresolved overloaded function
type>)’
     std::transform(str.begin(), str.end(), str.begin(), ::tolower);
                                                                  ^
In file included from /usr/include/c++/5/algorithm:62:0,
                 from main.cpp:3:
/usr/include/c++/5/bits/stl_algo.h:4164:5: note: candidate: template<class
_IIter, class _OIter, class _UnaryOperation> _OIter std::transform(_IIter,
_IIter, _OIter, _UnaryOperation)
     transform(_InputIterator __first, _InputIterator __last,
     ^
/usr/include/c++/5/bits/stl_algo.h:4164:5: note:   template argument
deduction/substitution failed:
main.cpp:23:66: note:   couldn't deduce template parameter ‘_UnaryOperation’
     std::transform(str.begin(), str.end(), str.begin(), ::tolower);
                                                                  ^
In file included from /usr/include/c++/5/algorithm:62:0,
                 from main.cpp:3:
/usr/include/c++/5/bits/stl_algo.h:4201:5: note: candidate: template<class
_IIter1, class _IIter2, class _OIter, class _BinaryOperation> _OIter
std::transform(_IIter1, _IIter1, _IIter2, _OIter, _BinaryOperation)
     transform(_InputIterator1 __first1, _InputIterator1 __last1,
     ^
/usr/include/c++/5/bits/stl_algo.h:4201:5: note:   template argument
deduction/substitution failed:
main.cpp:23:66: note:   candidate expects 5 arguments, 4 provided
     std::transform(str.begin(), str.end(), str.begin(), ::tolower);





//g++ -O2 -Wall -Wextra -Wpedantic -o main main.cpp

#include <algorithm>
#include <string>
#include <iostream>

void myfunc(int i)
{
    i = 10;

    std::cout << i;
}

void myfunc(std::string i)
{
    i = "10";

    std::cout << i;
}

void tolower(std::string & str)
{
    std::transform(str.begin(), str.end(), str.begin(), ::tolower);
}

int main (void)
{
    std::string caps = "FOO";

    tolower(caps);

    return 0;
}