Unexpected interpolate tokens in `quote_item!` macro

[ptal]

Recent changes (I guess #23085) make interpolated items unexpected when quoting items. The error is:expected one of const, extern, fn, pub, type, unsafe, or }, found an interpolated item``. The full failing code is available ptal/oak@20ddd3d and a snippet is below:

pub struct PegCompiler<'cx>
{
  cx: &'cx ExtCtxt<'cx>,
  top_level_items: Vec<rust::P<rust::Item>>
}

impl<'cx> PegCompiler<'cx>
{
  fn compile_peg(&mut self) {
    let items = &self.top_level_items;
    parser.push(quote_item!(self.cx,
        impl Parser
        {
          pub fn new() -> Parser
          {
            Parser
          }
          $items // <== Remove this, and the error dissapears.
        }).unwrap());
  }
}

On rustc 1.1.0-dev (441b3f0c2 2015-04-28) (built 2015-04-28)

[sunng87]

I confirm the same issue with my little Derive macro tojson_macros

Edit, my error is:

expected one of `;` or `}`, found `an interpolated statement`

[ptal]

As of rustc 1.1.0-dev (a979efc2f 2015-05-04) (built 2015-05-04) the error message changed: error: expected ident, found an interpolated item.

[ptal]

This bug persists but the interpolated item seems now "expanded", the new error is:

src/test/ntcc.rs:15:1: 138:2 error: expected one of `const`, `extern`, `fn`, `pub`, `type`, `unsafe`, or `}`, found `fn lt(input: &str, pos: usize) -> Result<usize, String> {
    match peg::runtime::match_literal(input, pos, "<", 1usize) {
        Ok(pos) => { Parser::spacing(input, pos) }
        x => x,
    }
}`

[ptal]

After investigations, it is normal that the code does not compile. This is due to the introduction of ImplItem. We tried to add free functions of type Item as method of an implementation (that should be of type ImplItem).

So the only problem is the bad error message.

[steveklabnik]

Triage: compiler plugin stuff is changing wildly; it will not be using this interface publicly. And given that is about a diagnostic, and nobody has commented in a while, I'm going to give this a close. If someone else sees a bad diagnostic like this with stable code, please let me know!