mirror of https://github.com/rust-lang/rust
62 lines
1.4 KiB
Rust
62 lines
1.4 KiB
Rust
//@ check-pass
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// Basic usage patterns of free & associated generic const items.
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#![feature(generic_const_items)]
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#![allow(incomplete_features)]
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fn main() {
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const NULL<T>: Option<T> = None::<T>;
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const NOTHING<T>: Option<T> = None; // arg inferred
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let _ = NOTHING::<String>;
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let _: Option<u8> = NULL; // arg inferred
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const IDENTITY<const X: u64>: u64 = X;
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const COUNT: u64 = IDENTITY::<48>;
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const AMOUNT: u64 = IDENTITY::<COUNT>;
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const NUMBER: u64 = IDENTITY::<{ AMOUNT * 2 }>;
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let _ = NUMBER;
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let _ = IDENTITY::<0>;
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let _ = match 0 {
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IDENTITY::<1> => 2,
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IDENTITY::<{ 1 + 1 }> => 4,
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_ => 0,
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};
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const CREATE<I: Inhabited>: I = I::PROOF;
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let _ = CREATE::<u64>;
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let _: u64 = CREATE; // arg inferred
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let _ = <() as Main<u64>>::MAKE::<u64>;
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let _: (u64, u64) = <()>::MAKE; // args inferred
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}
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pub fn usage<'any>() {
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const REGION_POLY<'a>: &'a () = &();
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let _: &'any () = REGION_POLY::<'any>;
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let _: &'any () = REGION_POLY::<'_>;
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let _: &'static () = REGION_POLY;
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}
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trait Main<O> {
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type Output<I>;
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const MAKE<I: Inhabited>: Self::Output<I>;
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}
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impl<O: Inhabited> Main<O> for () {
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type Output<I> = (O, I);
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const MAKE<I: Inhabited>: Self::Output<I> = (O::PROOF, I::PROOF);
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}
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trait Inhabited {
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const PROOF: Self;
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}
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impl Inhabited for u64 {
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const PROOF: Self = 512;
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}
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