boost::spirit::qi::phrase_parser() into std::map error - c++

Question

The below code is to parse a "key=val;.." string into std::map and it fails to compile with the error:
Error C2146 : syntax error: missing '>' before identifier 'value_type'
Error C2039 : 'value_type': is not a member of 'std::pair,std::allocator,std::basic_string,std::allocator>>' c:\git\risk-engine-core_tcp\stage\boost-1.66.0-barclays-1\include\boost\spirit\home\support\container.hpp
It does not like the last parameter, "contents" (std::map), passed as a container.
Boost version is 1.66
namespace qi = boost::spirit::qi;
std::map<std::string,std::string> contents;
std::string::iterator first = str.begin();
std::string::iterator last = str.end();
const bool result = qi::phrase_parse(first,last,
*( *(qi::char_-"=") >> qi::lit("=") >> *(qi::char_-";") >> -qi::lit(";") ),
ascii::space, contents);
Looking at the boost docs and stack overflow, I do not see any issue with the above code.

Answer 1

Did you include
#include <boost/fusion/adapted/std_pair.hpp>
Here's a working example with some improvement suggestions:
Live On Coliru
#include <boost/fusion/adapted/std_pair.hpp>
#include <boost/spirit/include/qi.hpp>
#include <map>
#include <iomanip> // std::quoted
namespace qi = boost::spirit::qi;
int main() {
std::string str("key = value");
std::string::const_iterator first = str.begin();
std::string::const_iterator last = str.end();
std::map<std::string, std::string> contents;
bool const result = qi::phrase_parse(first,last,
*( *~qi::char_('=') >> '=' >> *~qi::char_(';') >> -qi::lit(';') ),
qi::ascii::space, contents);
if (result) {
std::cout << "Parsed " << contents.size() << " elements\n";
for (auto& [k,v] : contents) {
std::cout << "\t" << std::quoted(k) << ": " << std::quoted(v) << "\n";
}
} else {
std::cout << "Parse failed\n";
}
if (first != last)
std::cout << "Remaining input unparsed: " << std::quoted(std::string(first, last)) << "\n";
}
Prints
Parsed 1 elements
"key": "value"