Quick C++ question for C++ experts :)

[Paulo César Pereira de Andrade]

2015-03-28 16:06 GMT-03:00 Paulo César Pereira de Andrade
<paulo.cesar.pereira.de.andrade at gmail.com>:
> Is this expected to not compile with -fno-implicit-templates?
>
> ---%<---
> $ cat test.cc
> #include <string>
> std::string test(int i)
> {
>     std::string t;
>     std::string s = "(";
>     t = "";
>     for (int r = i; r; r>>=1) {
>         if (r & 1)
>             t = "1" + t;
>         else
>             t = "0" + t;
>     }
>     s += t;
>     s += ")";
>     return s;
> }
>
> int
> main(int argc, char *argv[])
> {
>     std::string s = test(16);
>     return 0;
> }
>
> $ g++ -fno-implicit-templates test.cc
> /tmp/ccai7t5T.o: In function `test(int)':
> test.cc:(.text+0x9d): undefined reference to
> `std::__cxx11::basic_string<char, std::char_traits<char>,
> std::allocator<char> > std::operator+<char, std::char_traits<char>,
> std::allocator<char> >(char const*, std::__cxx11::basic_string<char,
> std::char_traits<char>, std::allocator<char> > const&)'
> test.cc:(.text+0xd9): undefined reference to
> `std::__cxx11::basic_string<char, std::char_traits<char>,
> std::allocator<char> > std::operator+<char, std::char_traits<char>,
> std::allocator<char> >(char const*, std::__cxx11::basic_string<char,
> std::char_traits<char>, std::allocator<char> > const&)'
> collect2: error: ld returned 1 exit status
> ---%<---

  I will open a gcc bug report. It must be a bug, because if using
a temporary to convert "1" or "0" to a std::string it works. Or,
explicit converting, e.g.:

-        t = "1" + t;
+        t = std::string("1") + t;

  My C++ foo is not that great, thus asking before opening a
bug report.

Thanks,
Paulo