tests/ui/zero_sized_hashmap_values.rs

#![warn(clippy::zero_sized_map_values)]
use std::collections::HashMap;

const CONST_OK: Option<HashMap<String, usize>> = None;
const CONST_NOT_OK: Option<HashMap<String, ()>> = None;
//~^ zero_sized_map_values

static STATIC_OK: Option<HashMap<String, usize>> = None;
static STATIC_NOT_OK: Option<HashMap<String, ()>> = None;
//~^ zero_sized_map_values

type OkMap = HashMap<String, usize>;
type NotOkMap = HashMap<String, ()>;
//~^ zero_sized_map_values

enum TestEnum {
    Ok(HashMap<String, usize>),
    NotOk(HashMap<String, ()>),
    //~^ zero_sized_map_values
}

struct Test {
    ok: HashMap<String, usize>,
    not_ok: HashMap<String, ()>,
    //~^ zero_sized_map_values
    also_not_ok: Vec<HashMap<usize, ()>>,
    //~^ zero_sized_map_values
}

trait TestTrait {
    type Output;

    fn produce_output() -> Self::Output;

    fn weird_map(&self, map: HashMap<usize, ()>);
    //~^ zero_sized_map_values
}

impl Test {
    fn ok(&self) -> HashMap<String, usize> {
        todo!()
    }

    fn not_ok(&self) -> HashMap<String, ()> {
        //~^ zero_sized_map_values

        todo!()
    }
}

impl TestTrait for Test {
    type Output = HashMap<String, ()>;

    fn produce_output() -> Self::Output {
        todo!();
    }

    fn weird_map(&self, map: HashMap<usize, ()>) {
        todo!();
    }
}

fn test(map: HashMap<String, ()>, key: &str) -> HashMap<String, ()> {
    //~^ zero_sized_map_values
    //~| zero_sized_map_values

    todo!();
}

fn test2(map: HashMap<String, usize>, key: &str) -> HashMap<String, usize> {
    todo!();
}

fn issue14822() {
    trait Trait {
        type T;
    }
    struct S<T: Trait>(T::T);

    // The `delay_bug` happens when evaluating the pointer metadata of `S<T>` which depends on
    // whether `T::T` is `Sized`. Since the type alias doesn't have a trait bound of `T: Trait`
    // evaluating `T::T: Sized` ultimately fails with `NoSolution`.
    type A<T> = HashMap<u32, *const S<T>>;
    type B<T> = HashMap<u32, S<T>>;

    enum E {}
    impl Trait for E {
        type T = ();
    }
    type C = HashMap<u32, *const S<E>>;
    type D = HashMap<u32, S<E>>;
    //~^ zero_sized_map_values
}

fn issue15429() {
    struct E<'a>(&'a [E<'a>]);

    // The assertion error happens when the type being evaluated has escaping bound vars
    // as it cannot be wrapped in a dummy binder during size computation.
    type F = dyn for<'a> FnOnce(HashMap<u32, E<'a>>) -> u32;
}

fn main() {
    let _: HashMap<String, ()> = HashMap::new();
    //~^ zero_sized_map_values
    //~| zero_sized_map_values

    let _: HashMap<String, usize> = HashMap::new();

    let _: HashMap<_, _> = std::iter::empty::<(String, ())>().collect();
    //~^ zero_sized_map_values
}