Panic when using dotted access syntax in attributes (regression from 0.18 to 0.19.1)

[Veetaha]

The new 0.19.1 version of strum_macros panics when reaches the dot operator expression in attributes metadata which might be used by snafu macros for example (see reproduction in the end).

The error message is so unhelpful that to understand where the bug comes from one needs clone this repo
and do a binary search with synthetically inserting panic!("Here") in code here and there.

The error message

error: proc-macro derive panicked
  --> crates/foo/src/main.rs:10:10
   |
10 | #[derive(IntoStaticStr)]
   |          ^^^^^^^^^^^^^
   |
   = help: message: called `Result::unwrap()` on an `Err` value: Error("expected `,`")

At the end of the day the panic comes from syn on this line of code:

strum/strum_macros/src/helpers/has_metadata.rs

Line 14 in a11862c

.map(|attr| attr.parse_meta().unwrap())

Change that unwrap() to expect("Boom") to check that this really is the place of panic.

Reproduction (panics on 0.19.1 of strum_macros, but version 0.18.0 works fine):

use snafu::Snafu; // "0.6.8"
use strum_macros::IntoStaticStr;

#[derive(Debug)]
struct Inner {
    foo: &'static str
}

#[derive(Debug, Snafu)]
#[derive(IntoStaticStr)] // if you comment out this line, the crate compiles well
enum Error {
    #[snafu(display("Inner: {}", inner.foo))] // inner.foo syntax causes the panic (probably the dot)
    A {
        inner: Inner
    }
}

fn main() {
    dbg!(Error::A { inner: Inner { foo: "bar" } });
}

cc #100

[Peternator7]

Should be fixed by #105. Can you verify locally?

[Veetaha]

Yup, with #105 there is no panic

[Peternator7]

PR is merged, and crate is published. 0.19.2 should fix this issue.

[Veetaha]

Great, thanks!