"Fill match arms" not offered inside `tokio::select!` arm

rust-analyzer version: rust-analyzer 1.94.0-nightly (fecb335c 2026-01-07)

rustc version: rustc 1.94.0-nightly (fecb335cb 2026-01-07)

editor or extension: Neovim

The "Fill match arms" code action doesn't appear when the cursor is on a line strictly between the opening and closing braces of a match inside an arm of tokio's select! macro.

Repro:

async fn repro() {
    tokio::select! {
        () = async { } => {
            match Some(42) { // Works if the cursor is on this line.
                // Doesn't work if cursor is on this line.
            } // Works if the cursor is on this line.
        }
    }
}

Related: #3936

Start by reproducing the issue with the provided Rust example in Neovim and compare the code action at the opening brace, inside the match, and at the closing brace. Trace how rust-analyzer handles match-arm completion inside the tokio::select! arm, using related issue #3936 for context. Done means "Fill match arms" appears from the interior line as well.