What does the rust-analyzer error "could not resolve macro `$crate::format_args`" mean and how do I fix it?

Question

I'm using rust-analyzer version 0.2.408 on Visual Studio Code.

I'm writing a command line application that involves centering text in the terminal. This is the function I wrote to do this:

use console::{Alignment, pad_str};

fn get_padded_row(row: &str, width: u16, symbol: Option<char>) -> String {
    let symbol = symbol.unwrap_or(' ');
    return pad_str(row, width as usize, Alignment::Center, None)
        .to_string()
        .replace(' ', &symbol.to_string());
}

This function works perfectly fine, and there were no errors with it. Then I wrote a test:

#[cfg(test)]
mod tests {
    use crate::get_padded_row;

    #[test]
    fn row_padding_dashes() {
        let padded_row = get_padded_row("hello", 15, Some('-'));
        assert_eq!(
            padded_row, "-----hello-----".to_string(),
            "`get_padded_row` was not correct, got `{}`", padded_row
        );
    }
}

The code still works perfectly fine. Both cargo run and cargo test work, the function passes the test, and cargo check returns no issues. But rust-analyzer gives an error, highlighting everything from the tr}; in the use statement to the p right after return: "could not resolve macro $crate::format_args rust-analyzer(macro-error)". Searching for this error returns nothing. VSCode links me to rust-analyzer user manual, which says only "This diagnostic is shown for macro expansion errors". Restarting VSCode and reinstalling rust-analyzer have done nothing. The error always comes back, and highlighting the same oddly specific region. The only way I've found to get rid of it while keeping rust-analyzer installed is to remove the test.

Judging from how the error is about macro expansion, and how removing the test fixes the issue, I'd imagine it's caused by the #[test] macro, but it's strange that rustc finds no issues at all with my code while rust-analyzer is freaking out about this error. So far, I've had better experiences with rust-analyzer than with the official Rust VSCode extension, but I'm on the verge of switching back to fix this issue.

Answer 1

This is a bug in rust-analyzer. For now, you can disable the warning in your settings.json:

"rust-analyzer.diagnostics.disabled": [
  "macro-error"
]

The bug was fixed on nightly, so you could install the nightly binary of rust-analyzer from GitHub, or you could just wait a couple days for the fix to land on stable.

Alternatively, you could downgrade to rls version 0.2.400, because the bug was caused by a commit in version 0.2.408:

Extensions Icon -> rust-analyzer -> Manage (gear icon) -> Install Another Version

Answer 2

Three months later and there seems to be a bug with Nightly release? Unsure.

I added unresolved-macro-call to Diagnostics: Disabled settings for rust-analyzer.