Does "Extract…" not work within macros?

Steps to reproduce:

1. cargo new <project>

2. open <project>/src/main.rs in VS Code with rust-analyzer:

   fn main() {
       println!("Hello, world!");
   }
   

3. select the string "Hello, world!"

4. right-click and select Refactor… from the context menu

Expected behavior:

• "Extract…" assists appear ("Extract into variable", "Extract into function")

Actual behavior:

• Only "Rewrite…" assists appear ("Rewrite as raw string", "Inline macro").

Notes:

1. I've verified that:

   • "extract" works fine for strings in other contexts (e.g. let s = "foo";)
   • the same behavior happens for non-strings in macros (e.g. I can't extract 2 from let v = vec![1, 2, 3];)

2. I tried using "Inline macro" in hopes of expanding till I was able to extract the string, but this didn't work; the println! call expands to

   {$crate::io::_print($crate::format_args_nl!("Hello, world!"));};
   

   which rust-analyzer isn't happy with ($ produces Syntax error: expected expression) — so I can't go on to expand format_args_nl! as I would assume I'd need to to get to the string.

I'm new to both Rust and VS Code, so I may be missing something. Coming from CLion, though, where Rust plugin handles it just fine, it seems a little weird.

I'm guessing CLion's doing something a bit hacky, while rust-analyzer's extract assist is trying to guarantee correctness, but the std macros must be common enough, I wonder if it isn't worth a little special-casing.

Reproduce the report from a new Cargo project by opening src/main.rs in VS Code with rust-analyzer and trying Refactor… on the string or a value inside a macro. Start by tracing rust-analyzer's extract-assist handling for macro arguments; done means the expected extraction assists appear without breaking the existing rewrite assists.