Doesn't work correctly with new Rust inline formatting

[RReverser]

Nowadays Rust supports inline formatting for variables like format!("Expected {a} to be {b}").

This syntax works correctly in format!, format_args!, anyhow! and a lot of other contexts.

However, in eyre, somewhat surprisingly, it treats the string as a literal and prints without interpolation, even though eyre itself has support for formatting when arguments are passed explicitly. It seems this stems from all macros (ensure!, bail!, eyre!) having a separate branch that catches string literal with no following arguments in a special way:

macro_rules! eyre {
    ($msg:literal $(,)?) => { ... };
    ($err:expr $(,)?) => { ... };
    ($fmt:expr, $($arg:tt)*) => { ... };
}

[nyurik]

Seems like an easy fix - should i submit a PR?

[nyurik]

Ah, turns out its already been fixed, but has not been released yet. Thx for all the hard work updating it. Can't wait for the new release!

[RReverser]

Oh, it was? Where did you see that?

[nyurik]

https://github.com/eyre-rs/eyre/blob/master/eyre/build.rs#L63-L69

[nyurik]

TBH, the implementation seems a bit convoluted, but I might simply not know enough about it. Most implementations I have seen simply rely on format_args! like so:

macro_rules! foo {
    ($($arg:tt)+) => {
        format_args!($($arg)+)
    };
}

[RReverser]

master/eyre/build.rs#L63-L69

I don't understand how the referenced lines are related to feature in question.

[nyurik]

They are used

eyre/eyre/src/lib.rs

Lines 1231 to 1234 in 0b24ae5

	#[cfg(eyre_no_fmt_arguments_as_str)]
	let fmt_arguments_as_str: Option<&str> = None;
	#[cfg(not(eyre_no_fmt_arguments_as_str))]
	let fmt_arguments_as_str = args.as_str();

and in a test

eyre/eyre/tests/test_macros.rs

Lines 78 to 85 in 0b24ae5

	#[cfg(not(eyre_no_fmt_args_capture))]
	fn test_capture_format_args() {
	maybe_install_handler().unwrap();
	let var = 42;
	let err = eyre!("interpolate {var}");
	assert_eq!("interpolate 42", err.to_string());
	}