Function c2rust_refactor::ast_manip::fold_output_exprs

pub fn fold_output_exprs<T, F>(target: &mut T, trailing: bool, callback: F) where
    T: MutVisit,
    F: FnMut(&mut P<Expr>), 

Rewrite function output/return expressions.

For the trailing expression of a block, only the leaf expressions will be visited - for example, in fn f() { if c { x } else { y } }, only x and y will be visited, not { x }, { y }, or the if.