&str lifetime when variable is borrowed as argument (not captured) by closure

fn myfn(str: &str) {
 let c = |s: &mut Option<&str>| *s = Some(str);
}

Compiler says

let c = |s: &mut Option<&str>| *s = Some(str);
  |                                 ^^^^^^^^^^^^^^ assignment requires that `'1` must outlive `'static`

If I change the code to

fn myfn(str: &str) {
 let mut var = None;
 let c = || var = Some(str);
}

It compiles.

[theemathas]

As a workaround, you can manually annotate the lifetime:

fn myfn<'a>(str: &'a str) {
    let c = |s: &mut Option<&'a str>| *s = Some(str);
}