gcc 10.1.0 can't std::stoull a string

problem with gcc 10.1.0 installed via guix:
std::stoull cannot work on a regular string, but requires wstring

code:

#include <iostream>
#include <string>

uint64_t _parse_number(std::string::const_iterator& c, const std::string::const_iterator& end)
{
    std::string::const_iterator s = c;
    while (c != end and isdigit(*c)) ++c;
    if (c > s) {
        return std::stoull(std::string(s,c));
    } else {
        return 0;
    }
}

int main(int argc, char** argv) {
    std::string s(argv[1]);
    std::string::const_iterator b = s.begin();
    std::string::const_iterator e = s.end();
    std::cout << _parse_number(b, e) << std::endl;
    return 0;
}

compile with:

g++ test-stoull.cpp -o test-stoull

yields this error:

test-stoull.cpp: In function ‘uint64_t _parse_number(std::__cxx11::basic_string<char>::const_iterator&, const const_iterator&)’:
test-stoull.cpp:9:33: error: invalid initialization of reference of type ‘const wstring&’ {aka ‘const std::__cxx11::basic_string<wchar_t>&’} from expression of type ‘std::string’ {aka ‘std::__cxx11::basic_string<char>’}
    9 |         return std::stoull(std::string(s,c));
      |                                 ^~~~~~~~~~~
In file included from /home/erikg/.guix-profile/include/c++/string:55,
                 from /home/erikg/.guix-profile/include/c++/bits/locale_classes.h:40,
                 from /home/erikg/.guix-profile/include/c++/bits/ios_base.h:41,
                 from /home/erikg/.guix-profile/include/c++/ios:42,
                 from /home/erikg/.guix-profile/include/c++/ostream:38,
                 from /home/erikg/.guix-profile/include/c++/iostream:39,
                 from test-stoull.cpp:1:
/home/erikg/.guix-profile/include/c++/bits/basic_string.h:6697:25: note: in passing argument 1 of ‘long long unsigned int std::__cxx11::stoull(const wstring&, std::size_t*, int)’
 6697 |   stoull(const wstring& __str, size_t* __idx = 0, int __base = 10)
      |          ~~~~~~~~~~~~~~~^~~~~


-> % gcc --version
gcc (GCC) 10.1.0
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This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.