Parser::into, From trait and chained parsers.

[Railroad6230]

Hi nom,

I'm writing a parser, and at some point I wanted to use the Parser::into method:

use nom::bytes::complete::take;
use nom::number::complete::{le_u64, le_u8};
use nom::{IResult, Parser};

pub struct MyType<'a> {
    pub content: &'a [u8],
    pub code: u8,
}

impl<'a> From<(u8, &'a [u8])> for MyType<'a> {
    fn from((code, content): (u8, &'a [u8])) -> Self {
        Self { content, code }
    }
}

fn base_parser(input: &[u8]) -> IResult<&[u8], (u8, &[u8])> {
    le_u8.and(le_u64.flat_map(take)).parse(input)
}

pub fn parse(input: &[u8]) -> IResult<&[u8], MyType> {
    base_parser.into().parse(input)
}

However, this leads to the following error:

error[E0034]: multiple applicable items in scope
  --> src/test.rs:29:17
   |
29 |     base_parser.into().parse(input)
   |                 ^^^^ multiple `into` found
   |
   = note: candidate #1 is defined in an impl of the trait `nom::Parser` for the type `F`
   = note: candidate #2 is defined in an impl of the trait `std::convert::Into` for the type `T`
help: disambiguate the method for candidate #1
   |
29 |     nom::Parser::into(base_parser).parse(input)
   |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
help: disambiguate the method for candidate #2
   |
29 |     std::convert::Into::into(base_parser).parse(input)
   | 

This error sounds correct and legit to me, and I've found the following workarounds:

pub fn parse(input: &[u8]) -> IResult<&[u8], MyType> {
    Parser::into(base_parser).parse(input)
}

pub fn parse(input: &[u8]) -> IResult<&[u8], MyType> {
    base_parser.map(MyType::from).parse(input)
}

I was wondering if the Parser::into(sub_parser) is the preferred form here?

I wanted to write my parser using chained parsers (parser1.then(parser2).and_then(parser3).or(parser4)) instead
of wrapped parsers (tuple(map(opt(…)))), but because of this error it seems that I will not be able to.

I think that renaming Parser::into to something else would solve it, but this may not be what you want.

I'm using nom 8.0.0 with rust 1.85.0.