> (It would know where to expect an identifier and where to expect an expression etc.)

But that doesn't mean that what's in the macro should be highlighted like Rust:

    sql!("SELECT * FROM users WHERE name = $1");

is a macro provided by https://github.com/sfackler/rust-postgres-macros , and should be highlighted like SQL, not like a Rust string.

    sql!("SELECT * FORM users WHERE name = $1");

throws an error, because it's malformed.