error: expected expression, found `let` statement --> $DIR/macro-expanded.rs:7:20 | LL | ($e:expr) => { let Some(x) = $e } | ^^^ ... LL | () if m!(Some(5)) => {} | ----------- in this macro invocation | = note: only supported directly in conditions of `if` and `while` expressions = note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info) error: aborting due to 1 previous error