Function rustfmt_nightly::closures::rewrite_closure_fn_decl

fn rewrite_closure_fn_decl(
    binder: &ClosureBinder,
    constness: Const,
    capture: CaptureBy,
    asyncness: &Async,
    movability: Movability,
    fn_decl: &FnDecl,
    body: &Expr,
    span: Span,
    context: &RewriteContext<'_>,
    shape: Shape
) -> Option<(String, usize)>