1 error: captured variable cannot escape `FnMut` closure body
2 --> $DIR/issue-40510-3.rs:7:9
4 LL | let mut x: Vec<()> = Vec::new();
5 | ----- variable defined here
8 | - inferred to be a `FnMut` closure
11 | | - variable captured here
13 | |_________^ returns a closure that contains a reference to a captured variable, which then escapes the closure body
15 = note: `FnMut` closures only have access to their captured variables while they are executing...
16 = note: ...therefore, they cannot allow references to captured variables to escape
17 help: consider adding 'move' keyword before the nested closure
22 error: aborting due to previous error