mirror of https://github.com/rust-lang/rust
124 lines
3.4 KiB
Rust
124 lines
3.4 KiB
Rust
#![feature(coverage_attribute)]
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#![feature(custom_inner_attributes)] // for #![rustfmt::skip]
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#![feature(noop_waker)]
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#![allow(unused_assignments, dead_code)]
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#![rustfmt::skip]
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//@ edition: 2018
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//@ compile-flags: -Copt-level=1
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async fn c(x: u8) -> u8 {
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if x == 8 {
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1
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} else {
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0
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}
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}
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async fn d() -> u8 { 1 }
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async fn e() -> u8 { 1 } // unused function; executor does not block on `g()`
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async fn f() -> u8 { 1 }
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async fn foo() -> [bool; 10] { [false; 10] } // unused function; executor does not block on `h()`
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pub async fn g(x: u8) {
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match x {
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y if e().await == y => (),
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y if f().await == y => (),
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_ => (),
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}
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}
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async fn h(x: usize) { // The function signature is counted when called, but the body is not
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// executed (not awaited) so the open brace has a `0` count (at least when
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// displayed with `llvm-cov show` in color-mode).
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match x {
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y if foo().await[y] => (),
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_ => (),
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}
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}
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async fn i(x: u8) { // line coverage is 1, but there are 2 regions:
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// (a) the function signature, counted when the function is called; and
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// (b) the open brace for the function body, counted once when the body is
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// executed asynchronously.
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match x {
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y if c(x).await == y + 1 => { d().await; }
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y if f().await == y + 1 => (),
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_ => (),
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}
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}
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fn j(x: u8) {
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// non-async versions of `c()`, `d()`, and `f()` to make it similar to async `i()`.
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fn c(x: u8) -> u8 {
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if x == 8 {
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1 // This line appears covered, but the 1-character expression span covering the `1`
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// is not executed. (`llvm-cov show` displays a `^0` below the `1` ). This is because
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// `fn j()` executes the open brace for the function body, followed by the function's
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// first executable statement, `match x`. Inner function declarations are not
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// "visible" to the MIR for `j()`, so the code region counts all lines between the
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// open brace and the first statement as executed, which is, in a sense, true.
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// `llvm-cov show` overcomes this kind of situation by showing the actual counts
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// of the enclosed coverages, (that is, the `1` expression was not executed, and
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// accurately displays a `0`).
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} else {
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0
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}
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}
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fn d() -> u8 { 1 } // inner function is defined in-line, but the function is not executed
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fn f() -> u8 { 1 }
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match x {
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y if c(x) == y + 1 => { d(); }
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y if f() == y + 1 => (),
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_ => (),
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}
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}
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fn k(x: u8) { // unused function
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match x {
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1 => (),
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2 => (),
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_ => (),
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}
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}
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fn l(x: u8) {
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match x {
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1 => (),
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2 => (),
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_ => (),
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}
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}
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async fn m(x: u8) -> u8 { x - 1 }
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fn main() {
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let _ = g(10);
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let _ = h(9);
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let mut future = Box::pin(i(8));
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j(7);
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l(6);
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let _ = m(5);
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executor::block_on(future.as_mut());
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}
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mod executor {
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use core::future::Future;
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use core::pin::pin;
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use core::task::{Context, Poll, Waker};
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#[coverage(off)]
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pub fn block_on<F: Future>(mut future: F) -> F::Output {
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let mut future = pin!(future);
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let mut context = Context::from_waker(Waker::noop());
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loop {
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if let Poll::Ready(val) = future.as_mut().poll(&mut context) {
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break val;
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}
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}
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}
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}
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