tests/ui/swap_with_temporary.fixed

#![warn(clippy::swap_with_temporary)]

use std::mem::swap;

fn func() -> String {
    String::from("func")
}

fn func_returning_refmut(s: &mut String) -> &mut String {
    s
}

fn main() {
    let mut x = String::from("x");
    let mut y = String::from("y");
    let mut zz = String::from("zz");
    let z = &mut zz;

    // No lint
    swap(&mut x, &mut y);

    y = func();
    //~^ ERROR: swapping with a temporary value is inefficient

    x = func();
    //~^ ERROR: swapping with a temporary value is inefficient

    *z = func();
    //~^ ERROR: swapping with a temporary value is inefficient

    // No lint
    swap(z, func_returning_refmut(&mut x));

    swap(&mut y, z);

    *z = func();
    //~^ ERROR: swapping with a temporary value is inefficient

    macro_rules! mac {
        (refmut $x:expr) => {
            &mut $x
        };
        (funcall $f:ident) => {
            $f()
        };
        (wholeexpr) => {
            swap(&mut 42, &mut 0)
        };
        (ident $v:ident) => {
            $v
        };
    }
    *z = mac!(funcall func);
    //~^ ERROR: swapping with a temporary value is inefficient
    *mac!(ident z) = mac!(funcall func);
    //~^ ERROR: swapping with a temporary value is inefficient
    *mac!(ident z) = mac!(funcall func);
    //~^ ERROR: swapping with a temporary value is inefficient
    *mac!(refmut y) = func();
    //~^ ERROR: swapping with a temporary value is inefficient

    // No lint if it comes from a macro as it may depend on the arguments
    mac!(wholeexpr);
}

struct S {
    t: String,
}

fn dont_lint_those(s: &mut S, v: &mut [String], w: Option<&mut String>) {
    swap(&mut s.t, &mut v[0]);
    swap(&mut s.t, v.get_mut(0).unwrap());
    swap(w.unwrap(), &mut s.t);
}