Macro lifetimes aren't a thing (yet)

[Phlosioneer]

The return value of one of my named! parsers has a lifetime parameter. I need to make the function take a lifetime parameter. Does nom currently support this?

My situation:

pub enum Expression<'a> {
  String(&'a str)
  // other stuff...
}

named!(pub string_parser<Expression<'a> >,
  // other stuff...
  );

Cargo gives:

src/expressions.rs:15:22: 15:24 error: use of undeclared lifetime name `'a` [E0261]
src/expressions.rs:15 named!(pub string_parser<&'a str>, 
                                                ^~
src/expressions.rs:15:1: 19:5 note: in this expansion of named! (defined in <nom macros>)
src/expressions.rs:15:22: 15:24 help: run `rustc --explain E0261` to see a detailed explanation

The expanded macro definition:

pub fn string_parser(i: &[u8]) -> ::nom::IResult<&[u8], Expression<'a>, u32> {

'a is equal to the lifetime of the data being parsed, if that helps. Rust was able to infer that when it wasn't public, but as public it can't make that assumption.

[Phlosioneer]

Turns out this is an issue in rust: rust-lang/rust#27832

[Phlosioneer]

Just a few days ago, this issue was fixed in the RFC rust-lang/rfcs#1590. The PR against rustc is coming soon. So it'll be in nightly soonish. At that point, I'll probably do a personal fork of nom to add the nightly feature, unless there's a way for nom to handle nightly.

Closing because this isn't an issue anymore.

[Geal]

you could at least leave me some time to answer before closing ;)

named! is just a helper, you can always write your own function definition. I probably wouldn't add something that only appears in nightly, or at least I would hide it behind a feature flag.