On Mon, Jul 18, 2022 at 11:01 PM Seth via Boost wrote:

A literal b in a parser expression created `qi::lit(b)`. `qi::lit` does not "have" (synthesize/expose) an attribute. You want either `qi::alpha | qi::char_("._")`, or `qi::char_("a-zA-Z0-9_.")` or even (as you're in a lexeme anyways) `raw[alpha >> *(alnum|'.'|'_')]` because for `raw[]` the synthesized attribute is the source iterator range.

First fix: http://coliru.stacked-crooked.com/a/c5d9ee594370ac91

Seeing that your `identifier` is a lexeme, you should just drop the skipper (see https://stackoverflow.com/a/17073965/85371).

In the absense of semantic actions `%=` is redundant.

I don't recommend using classic spirit features in 2022.

All in all: https://godbolt.org/z/r6MPvK5aK

Hi Seth, Thanks! It's old, untouched code, hence the use of classic. I still don't get why it's returning "a\0b" though, where does the \0 come from? The code must've worked in the past, was the behavior of classic spirit changed? Or did I rely on undefined behavior? Your code parses multiple identifiers instead of just one, is that on purpose? Greetings, Olaf

On Mon, Jul 18, 2022, at 9:24 AM, Olaf van der Spek via Boost wrote:

...

Hi,

The underscore is parsed as a null character. Is this expected. A bug?

If a full repro is needed I can create one.

qi::rule identifier; identifier %= lexeme[alpha >> *(alnum | '.' | '_')];

typedef boost::spirit::classic::position_iterator iterator_t;

std::string s = "a_b blah"; iterator_t is(s.c_str(), s.c_str() + s.size(), "<name>");

std::string out; bool res = qi::phrase_parse(is, iterator_t(), identifier, skip, out); if (!res && is != iterator_t()) error_handler_::err(is); cout << out.size() << "|" << out << "|\n"; cout << int(out[0]) << " " << int(out[1]) << " " << int(out[2]) << "\n";

Output: // 3|ab| // 97 0 98

Greetings, -- Olaf

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-- Olaf