diff --git a/compiler/rustc_ty_utils/src/needs_drop.rs b/compiler/rustc_ty_utils/src/needs_drop.rs index 1118671a679..67ccfe7e78a 100644 --- a/compiler/rustc_ty_utils/src/needs_drop.rs +++ b/compiler/rustc_ty_utils/src/needs_drop.rs @@ -67,7 +67,7 @@ struct NeedsDropTypes<'tcx, F> { tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, // Whether to reveal coroutine witnesses, this is set - // to `false` unless we compute `needs_drop` for a generator witness. + // to `false` unless we compute `needs_drop` for a coroutine witness. reveal_coroutine_witnesses: bool, query_ty: Ty<'tcx>, seen_tys: FxHashSet>, @@ -138,11 +138,11 @@ fn next(&mut self) -> Option>> { // computed on MIR, while this very method is used to build MIR. // To avoid cycles, we consider that coroutines always require drop. // - // HACK: Because we erase regions contained in the generator witness, we + // HACK: Because we erase regions contained in the coroutine witness, we // have to conservatively assume that every region captured by the - // generator has to be live when dropped. This results in a lot of + // coroutine has to be live when dropped. This results in a lot of // undesirable borrowck errors. During borrowck, we call `needs_drop` - // for the generator witness and check whether any of the contained types + // for the coroutine witness and check whether any of the contained types // need to be dropped, and only require the captured types to be live // if they do. ty::Coroutine(_, args, _) => { diff --git a/tests/ui/dropck/coroutine-liveness-1.rs b/tests/ui/dropck/coroutine-liveness-1.rs new file mode 100644 index 00000000000..aea4d15ad90 --- /dev/null +++ b/tests/ui/dropck/coroutine-liveness-1.rs @@ -0,0 +1,18 @@ +// check-pass +// edition: 2021 + +// regression test for #116242. +use std::future; + +fn main() { + let mut recv = future::ready(()); + let _combined_fut = async { + let _ = || read(&mut recv); + }; + + drop(recv); +} + +fn read(_: &mut F) -> F::Output { + todo!() +} diff --git a/tests/ui/dropck/coroutine-liveness-2.rs b/tests/ui/dropck/coroutine-liveness-2.rs new file mode 100644 index 00000000000..416a073c6b9 --- /dev/null +++ b/tests/ui/dropck/coroutine-liveness-2.rs @@ -0,0 +1,23 @@ +// check-pass +// edition: 2021 + +// regression test found while working on #117134. +use std::future; + +fn main() { + let mut recv = future::ready(()); + let _combined_fut = async { + let _ = || read(&mut recv); + }; + + let _uwu = (String::new(), _combined_fut); + // Dropping a coroutine as part of a more complex + // types should not add unnecessary liveness + // constraints. + + drop(recv); +} + +fn read(_: &mut F) -> F::Output { + todo!() +}