138 lines
3.0 KiB
Rust
138 lines
3.0 KiB
Rust
//! Tests that coroutine discriminant sizes and ranges are chosen optimally and that they are
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//! reflected in the output of `mem::discriminant`.
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//@ run-pass
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#![feature(coroutines, coroutine_trait, core_intrinsics, discriminant_kind)]
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use std::intrinsics::discriminant_value;
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use std::marker::DiscriminantKind;
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use std::mem::size_of_val;
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use std::{cmp, ops::*};
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macro_rules! yield25 {
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($e:expr) => {
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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yield $e;
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};
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}
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/// Yields 250 times.
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macro_rules! yield250 {
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() => {
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yield250!(())
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};
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($e:expr) => {
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yield25!($e);
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yield25!($e);
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yield25!($e);
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yield25!($e);
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yield25!($e);
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yield25!($e);
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yield25!($e);
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yield25!($e);
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yield25!($e);
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yield25!($e);
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};
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}
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fn cycle(
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gen: impl Coroutine<()> + Unpin + DiscriminantKind<Discriminant = u32>,
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expected_max_discr: u32,
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) {
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let mut gen = Box::pin(gen);
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let mut max_discr = 0;
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loop {
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max_discr = cmp::max(max_discr, discriminant_value(gen.as_mut().get_mut()));
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match gen.as_mut().resume(()) {
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CoroutineState::Yielded(_) => {}
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CoroutineState::Complete(_) => {
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assert_eq!(max_discr, expected_max_discr);
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return;
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}
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}
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}
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}
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fn main() {
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// Has only one invalid discr. value.
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let gen_u8_tiny_niche = || {
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#[coroutine] || {
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// 3 reserved variants
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yield250!(); // 253 variants
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yield; // 254
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yield; // 255
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}
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};
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// Uses all values in the u8 discriminant.
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let gen_u8_full = || {
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#[coroutine] || {
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// 3 reserved variants
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yield250!(); // 253 variants
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yield; // 254
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yield; // 255
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yield; // 256
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}
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};
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// Barely needs a u16 discriminant.
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let gen_u16 = || {
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#[coroutine] || {
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// 3 reserved variants
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yield250!(); // 253 variants
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yield; // 254
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yield; // 255
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yield; // 256
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yield; // 257
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}
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};
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assert_eq!(size_of_val(&gen_u8_tiny_niche()), 1);
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assert_eq!(size_of_val(&Some(gen_u8_tiny_niche())), 1); // uses niche
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assert_eq!(size_of_val(&Some(Some(gen_u8_tiny_niche()))), 2); // cannot use niche anymore
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assert_eq!(size_of_val(&gen_u8_full()), 1);
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assert_eq!(size_of_val(&Some(gen_u8_full())), 2); // cannot use niche
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assert_eq!(size_of_val(&gen_u16()), 2);
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assert_eq!(size_of_val(&Some(gen_u16())), 2); // uses niche
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cycle(gen_u8_tiny_niche(), 254);
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cycle(gen_u8_full(), 255);
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cycle(gen_u16(), 256);
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}
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