diff --git a/src/test/ui/async-await/async-is-unwindsafe.rs b/src/test/ui/async-await/async-is-unwindsafe.rs new file mode 100644 index 0000000000000..56ed2847292d1 --- /dev/null +++ b/src/test/ui/async-await/async-is-unwindsafe.rs @@ -0,0 +1,30 @@ +// edition:2018 + +fn is_unwindsafe(_: impl std::panic::UnwindSafe) {} + +fn main() { + // A normal future created by an async block takes a `&mut Context<'_>` argument. + // That should not leak through to the whole async block. + is_unwindsafe(async { + async {}.await; // this needs an inner await point + }); + + is_unwindsafe(async { + //~^ ERROR the type `&mut Context<'_>` may not be safely transferred across an unwind boundary + use std::ptr::null; + use std::task::{Context, RawWaker, RawWakerVTable, Waker}; + let waker = unsafe { + Waker::from_raw(RawWaker::new( + null(), + &RawWakerVTable::new(|_| todo!(), |_| todo!(), |_| todo!(), |_| todo!()), + )) + }; + let mut cx = Context::from_waker(&waker); + let cx_ref = &mut cx; + + async {}.await; // this needs an inner await point + + // in this case, `&mut Context<'_>` is *truly* alive across an await point + drop(cx_ref); + }); +} diff --git a/src/test/ui/async-await/async-is-unwindsafe.stderr b/src/test/ui/async-await/async-is-unwindsafe.stderr new file mode 100644 index 0000000000000..d6404b30e74f1 --- /dev/null +++ b/src/test/ui/async-await/async-is-unwindsafe.stderr @@ -0,0 +1,38 @@ +error[E0277]: the type `&mut Context<'_>` may not be safely transferred across an unwind boundary + --> $DIR/async-is-unwindsafe.rs:12:19 + | +LL | is_unwindsafe(async { + | ___________________^ +LL | | +LL | | use std::ptr::null; +LL | | use std::task::{Context, RawWaker, RawWakerVTable, Waker}; +... | +LL | | drop(cx_ref); +LL | | }); + | | ^ + | | | + | |_____`&mut Context<'_>` may not be safely transferred across an unwind boundary + | within this `[async block@$DIR/async-is-unwindsafe.rs:12:19: 29:6]` + | + = help: within `[async block@$DIR/async-is-unwindsafe.rs:12:19: 29:6]`, the trait `UnwindSafe` is not implemented for `&mut Context<'_>` + = note: `UnwindSafe` is implemented for `&std::task::Context<'_>`, but not for `&mut std::task::Context<'_>` +note: future does not implement `UnwindSafe` as this value is used across an await + --> $DIR/async-is-unwindsafe.rs:25:17 + | +LL | let cx_ref = &mut cx; + | ------ has type `&mut Context<'_>` which does not implement `UnwindSafe` +LL | +LL | async {}.await; // this needs an inner await point + | ^^^^^^ await occurs here, with `cx_ref` maybe used later +... +LL | }); + | - `cx_ref` is later dropped here +note: required by a bound in `is_unwindsafe` + --> $DIR/async-is-unwindsafe.rs:3:26 + | +LL | fn is_unwindsafe(_: impl std::panic::UnwindSafe) {} + | ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_unwindsafe` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0277`.