rust/tests/ui/lang-items/lang-item-generic-requirements.rs

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// Checks that declaring a lang item with the wrong number of generic arguments errors rather than
// crashing (issue #83474, #83893, #87573, part of #9307, #79559).
#![feature(lang_items, no_core)]
#![no_core]
#[lang = "sized"]
trait MySized {}
#[lang = "add"]
trait MyAdd<'a, T> {}
//~^^ ERROR: `add` lang item must be applied to a trait with 1 generic argument [E0718]
#[lang = "drop_in_place"]
//~^ ERROR `drop_in_place` lang item must be applied to a function with at least 1 generic
fn my_ptr_drop() {}
#[lang = "index"]
trait MyIndex<'a, T> {}
//~^^ ERROR: `index` lang item must be applied to a trait with 1 generic argument [E0718]
#[lang = "phantom_data"]
//~^ ERROR `phantom_data` lang item must be applied to a struct with 1 generic argument
struct MyPhantomData<T, U>;
//~^ ERROR `T` is never used
//~| ERROR `U` is never used
#[lang = "owned_box"]
//~^ ERROR `owned_box` lang item must be applied to a struct with at least 1 generic argument
struct Foo;
// When the `start` lang item is missing generics very odd things can happen, especially when
// it comes to cross-crate monomorphization
#[lang = "start"]
//~^ ERROR `start` lang item must be applied to a function with 1 generic argument [E0718]
fn start(_: *const u8, _: isize, _: *const *const u8) -> isize {
0
}
fn ice() {
// Use add
let r = 5;
let a = 6;
r + a; //~ ERROR cannot add
// Use drop in place
my_ptr_drop();
// Use index
let arr = [0; 5];
let _ = arr[2];
// Use phantomdata
let _ = MyPhantomData::<(), i32>;
// Use Foo
let _: () = Foo;
}
// use `start`
fn main() {}