diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_data_structures/src/graph/dominators/mod.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0208.md | 45 | ||||
| -rw-r--r-- | compiler/rustc_hir/src/hir.rs | 8 | ||||
| -rw-r--r-- | compiler/rustc_hir/src/lang_items.rs | 1 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/variance/test.rs | 5 | ||||
| -rw-r--r-- | compiler/rustc_hir_typeck/src/cast.rs | 38 | ||||
| -rw-r--r-- | compiler/rustc_middle/src/ty/context.rs | 9 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/coverage/spans.rs | 10 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/generator.rs | 118 | ||||
| -rw-r--r-- | compiler/rustc_span/src/symbol.rs | 1 | ||||
| -rw-r--r-- | compiler/rustc_ty_utils/src/abi.rs | 34 |
11 files changed, 231 insertions, 40 deletions
diff --git a/compiler/rustc_data_structures/src/graph/dominators/mod.rs b/compiler/rustc_data_structures/src/graph/dominators/mod.rs index 07b1ace2189..fb2a22e94a5 100644 --- a/compiler/rustc_data_structures/src/graph/dominators/mod.rs +++ b/compiler/rustc_data_structures/src/graph/dominators/mod.rs @@ -299,7 +299,7 @@ impl<Node: Idx> Dominators<Node> { /// of two unrelated nodes will also be consistent, but otherwise the order has no /// meaning.) This method cannot be used to determine if either Node dominates the other. pub fn rank_partial_cmp(&self, lhs: Node, rhs: Node) -> Option<Ordering> { - self.post_order_rank[lhs].partial_cmp(&self.post_order_rank[rhs]) + self.post_order_rank[rhs].partial_cmp(&self.post_order_rank[lhs]) } } diff --git a/compiler/rustc_error_codes/src/error_codes/E0208.md b/compiler/rustc_error_codes/src/error_codes/E0208.md index 7edd93e56a9..1ae01106f20 100644 --- a/compiler/rustc_error_codes/src/error_codes/E0208.md +++ b/compiler/rustc_error_codes/src/error_codes/E0208.md @@ -1 +1,46 @@ #### This error code is internal to the compiler and will not be emitted with normal Rust code. +#### Note: this error code is no longer emitted by the compiler. + +This error code shows the variance of a type's generic parameters. + +Erroneous code example: + +```compile_fail +// NOTE: this feature is perma-unstable and should *only* be used for +// testing purposes. +#![feature(rustc_attrs)] + +#[rustc_variance] +struct Foo<'a, T> { // error: deliberate error to display type's variance + t: &'a mut T, +} +``` + +which produces the following error: + +```text +error: [-, o] + --> <anon>:4:1 + | +4 | struct Foo<'a, T> { + | ^^^^^^^^^^^^^^^^^ +``` + +*Note that while `#[rustc_variance]` still exists and is used within the* +*compiler, it no longer is marked as `E0208` and instead has no error code.* + +This error is deliberately triggered with the `#[rustc_variance]` attribute +(`#![feature(rustc_attrs)]` must be enabled) and helps to show you the variance +of the type's generic parameters. You can read more about variance and +subtyping in [this section of the Rustnomicon]. For a more in depth look at +variance (including a more complete list of common variances) see +[this section of the Reference]. For information on how variance is implemented +in the compiler, see [this section of `rustc-dev-guide`]. + +This error can be easily fixed by removing the `#[rustc_variance]` attribute, +the compiler's suggestion to comment it out can be applied automatically with +`rustfix`. + +[this section of the Rustnomicon]: https://doc.rust-lang.org/nomicon/subtyping.html +[this section of the Reference]: https://doc.rust-lang.org/reference/subtyping.html#variance +[this section of `rustc-dev-guide`]: https://rustc-dev-guide.rust-lang.org/variance.html diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs index 56f0e0b3e7d..d6566860f81 100644 --- a/compiler/rustc_hir/src/hir.rs +++ b/compiler/rustc_hir/src/hir.rs @@ -1787,6 +1787,14 @@ impl Expr<'_> { expr } + pub fn peel_borrows(&self) -> &Self { + let mut expr = self; + while let ExprKind::AddrOf(.., inner) = &expr.kind { + expr = inner; + } + expr + } + pub fn can_have_side_effects(&self) -> bool { match self.peel_drop_temps().kind { ExprKind::Path(_) | ExprKind::Lit(_) => false, diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs index 3474fab34f0..54fa5702fbc 100644 --- a/compiler/rustc_hir/src/lang_items.rs +++ b/compiler/rustc_hir/src/lang_items.rs @@ -291,6 +291,7 @@ language_item_table! { IdentityFuture, sym::identity_future, identity_future_fn, Target::Fn, GenericRequirement::None; GetContext, sym::get_context, get_context_fn, Target::Fn, GenericRequirement::None; + Context, sym::Context, context, Target::Struct, GenericRequirement::None; FuturePoll, sym::poll, future_poll_fn, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None; FromFrom, sym::from, from_fn, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None; diff --git a/compiler/rustc_hir_analysis/src/variance/test.rs b/compiler/rustc_hir_analysis/src/variance/test.rs index 83ed3e44b3d..5feeb92d337 100644 --- a/compiler/rustc_hir_analysis/src/variance/test.rs +++ b/compiler/rustc_hir_analysis/src/variance/test.rs @@ -1,4 +1,3 @@ -use rustc_errors::struct_span_err; use rustc_middle::ty::TyCtxt; use rustc_span::symbol::sym; @@ -8,8 +7,8 @@ pub fn test_variance(tcx: TyCtxt<'_>) { for id in tcx.hir().items() { if tcx.has_attr(id.owner_id.to_def_id(), sym::rustc_variance) { let variances_of = tcx.variances_of(id.owner_id); - struct_span_err!(tcx.sess, tcx.def_span(id.owner_id), E0208, "{:?}", variances_of) - .emit(); + + tcx.sess.struct_span_err(tcx.def_span(id.owner_id), format!("{variances_of:?}")).emit(); } } } diff --git a/compiler/rustc_hir_typeck/src/cast.rs b/compiler/rustc_hir_typeck/src/cast.rs index 0a230fca107..712f9b87aed 100644 --- a/compiler/rustc_hir_typeck/src/cast.rs +++ b/compiler/rustc_hir_typeck/src/cast.rs @@ -31,6 +31,7 @@ use super::FnCtxt; use crate::type_error_struct; +use hir::ExprKind; use rustc_errors::{ struct_span_err, Applicability, DelayDm, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, }; @@ -151,7 +152,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { #[derive(Copy, Clone)] pub enum CastError { - ErrorGuaranteed, + ErrorGuaranteed(ErrorGuaranteed), CastToBool, CastToChar, @@ -176,8 +177,8 @@ pub enum CastError { } impl From<ErrorGuaranteed> for CastError { - fn from(_: ErrorGuaranteed) -> Self { - CastError::ErrorGuaranteed + fn from(err: ErrorGuaranteed) -> Self { + CastError::ErrorGuaranteed(err) } } @@ -225,11 +226,10 @@ impl<'a, 'tcx> CastCheck<'tcx> { fn report_cast_error(&self, fcx: &FnCtxt<'a, 'tcx>, e: CastError) { match e { - CastError::ErrorGuaranteed => { + CastError::ErrorGuaranteed(_) => { // an error has already been reported } CastError::NeedDeref => { - let error_span = self.span; let mut err = make_invalid_casting_error( fcx.tcx.sess, self.span, @@ -237,21 +237,25 @@ impl<'a, 'tcx> CastCheck<'tcx> { self.cast_ty, fcx, ); - let cast_ty = fcx.ty_to_string(self.cast_ty); - err.span_label( - error_span, - format!("cannot cast `{}` as `{}`", fcx.ty_to_string(self.expr_ty), cast_ty), - ); - if let Ok(snippet) = fcx.sess().source_map().span_to_snippet(self.expr_span) { - err.span_suggestion( - self.expr_span, - "dereference the expression", - format!("*{}", snippet), - Applicability::MaybeIncorrect, + + if matches!(self.expr.kind, ExprKind::AddrOf(..)) { + // get just the borrow part of the expression + let span = self.expr_span.with_hi(self.expr.peel_borrows().span.lo()); + err.span_suggestion_verbose( + span, + "remove the unneeded borrow", + "", + Applicability::MachineApplicable, ); } else { - err.span_help(self.expr_span, "dereference the expression with `*`"); + err.span_suggestion_verbose( + self.expr_span.shrink_to_lo(), + "dereference the expression", + "*", + Applicability::MachineApplicable, + ); } + err.emit(); } CastError::NeedViaThinPtr | CastError::NeedViaPtr => { diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs index 0c66443555f..ce04d8d21f4 100644 --- a/compiler/rustc_middle/src/ty/context.rs +++ b/compiler/rustc_middle/src/ty/context.rs @@ -1952,6 +1952,15 @@ impl<'tcx> TyCtxt<'tcx> { self.mk_ty(GeneratorWitness(types)) } + /// Creates a `&mut Context<'_>` [`Ty`] with erased lifetimes. + pub fn mk_task_context(self) -> Ty<'tcx> { + let context_did = self.require_lang_item(LangItem::Context, None); + let context_adt_ref = self.adt_def(context_did); + let context_substs = self.intern_substs(&[self.lifetimes.re_erased.into()]); + let context_ty = self.mk_adt(context_adt_ref, context_substs); + self.mk_mut_ref(self.lifetimes.re_erased, context_ty) + } + #[inline] pub fn mk_ty_var(self, v: TyVid) -> Ty<'tcx> { self.mk_ty_infer(TyVar(v)) diff --git a/compiler/rustc_mir_transform/src/coverage/spans.rs b/compiler/rustc_mir_transform/src/coverage/spans.rs index 9f842c929dc..c5434840453 100644 --- a/compiler/rustc_mir_transform/src/coverage/spans.rs +++ b/compiler/rustc_mir_transform/src/coverage/spans.rs @@ -341,11 +341,11 @@ impl<'a, 'tcx> CoverageSpans<'a, 'tcx> { if a.is_in_same_bcb(b) { Some(Ordering::Equal) } else { - // Sort equal spans by dominator relationship, in reverse order (so - // dominators always come after the dominated equal spans). When later - // comparing two spans in order, the first will either dominate the second, - // or they will have no dominator relationship. - self.basic_coverage_blocks.dominators().rank_partial_cmp(b.bcb, a.bcb) + // Sort equal spans by dominator relationship (so dominators always come + // before the dominated equal spans). When later comparing two spans in + // order, the first will either dominate the second, or they will have no + // dominator relationship. + self.basic_coverage_blocks.dominators().rank_partial_cmp(a.bcb, b.bcb) } } else { // Sort hi() in reverse order so shorter spans are attempted after longer spans. diff --git a/compiler/rustc_mir_transform/src/generator.rs b/compiler/rustc_mir_transform/src/generator.rs index c097af61611..39c61a34afc 100644 --- a/compiler/rustc_mir_transform/src/generator.rs +++ b/compiler/rustc_mir_transform/src/generator.rs @@ -460,6 +460,104 @@ fn replace_local<'tcx>( new_local } +/// Transforms the `body` of the generator applying the following transforms: +/// +/// - Eliminates all the `get_context` calls that async lowering created. +/// - Replace all `Local` `ResumeTy` types with `&mut Context<'_>` (`context_mut_ref`). +/// +/// The `Local`s that have their types replaced are: +/// - The `resume` argument itself. +/// - The argument to `get_context`. +/// - The yielded value of a `yield`. +/// +/// The `ResumeTy` hides a `&mut Context<'_>` behind an unsafe raw pointer, and the +/// `get_context` function is being used to convert that back to a `&mut Context<'_>`. +/// +/// Ideally the async lowering would not use the `ResumeTy`/`get_context` indirection, +/// but rather directly use `&mut Context<'_>`, however that would currently +/// lead to higher-kinded lifetime errors. +/// See <https://github.com/rust-lang/rust/issues/105501>. +/// +/// The async lowering step and the type / lifetime inference / checking are +/// still using the `ResumeTy` indirection for the time being, and that indirection +/// is removed here. After this transform, the generator body only knows about `&mut Context<'_>`. +fn transform_async_context<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { + let context_mut_ref = tcx.mk_task_context(); + + // replace the type of the `resume` argument + replace_resume_ty_local(tcx, body, Local::new(2), context_mut_ref); + + let get_context_def_id = tcx.require_lang_item(LangItem::GetContext, None); + + for bb in BasicBlock::new(0)..body.basic_blocks.next_index() { + let bb_data = &body[bb]; + if bb_data.is_cleanup { + continue; + } + + match &bb_data.terminator().kind { + TerminatorKind::Call { func, .. } => { + let func_ty = func.ty(body, tcx); + if let ty::FnDef(def_id, _) = *func_ty.kind() { + if def_id == get_context_def_id { + let local = eliminate_get_context_call(&mut body[bb]); + replace_resume_ty_local(tcx, body, local, context_mut_ref); + } + } else { + continue; + } + } + TerminatorKind::Yield { resume_arg, .. } => { + replace_resume_ty_local(tcx, body, resume_arg.local, context_mut_ref); + } + _ => {} + } + } +} + +fn eliminate_get_context_call<'tcx>(bb_data: &mut BasicBlockData<'tcx>) -> Local { + let terminator = bb_data.terminator.take().unwrap(); + if let TerminatorKind::Call { mut args, destination, target, .. } = terminator.kind { + let arg = args.pop().unwrap(); + let local = arg.place().unwrap().local; + + let arg = Rvalue::Use(arg); + let assign = Statement { + source_info: terminator.source_info, + kind: StatementKind::Assign(Box::new((destination, arg))), + }; + bb_data.statements.push(assign); + bb_data.terminator = Some(Terminator { + source_info: terminator.source_info, + kind: TerminatorKind::Goto { target: target.unwrap() }, + }); + local + } else { + bug!(); + } +} + +#[cfg_attr(not(debug_assertions), allow(unused))] +fn replace_resume_ty_local<'tcx>( + tcx: TyCtxt<'tcx>, + body: &mut Body<'tcx>, + local: Local, + context_mut_ref: Ty<'tcx>, +) { + let local_ty = std::mem::replace(&mut body.local_decls[local].ty, context_mut_ref); + // We have to replace the `ResumeTy` that is used for type and borrow checking + // with `&mut Context<'_>` in MIR. + #[cfg(debug_assertions)] + { + if let ty::Adt(resume_ty_adt, _) = local_ty.kind() { + let expected_adt = tcx.adt_def(tcx.require_lang_item(LangItem::ResumeTy, None)); + assert_eq!(*resume_ty_adt, expected_adt); + } else { + panic!("expected `ResumeTy`, found `{:?}`", local_ty); + }; + } +} + struct LivenessInfo { /// Which locals are live across any suspension point. saved_locals: GeneratorSavedLocals, @@ -1283,13 +1381,13 @@ impl<'tcx> MirPass<'tcx> for StateTransform { } }; - let is_async_kind = body.generator_kind().unwrap() != GeneratorKind::Gen; + let is_async_kind = matches!(body.generator_kind(), Some(GeneratorKind::Async(_))); let (state_adt_ref, state_substs) = if is_async_kind { // Compute Poll<return_ty> - let state_did = tcx.require_lang_item(LangItem::Poll, None); - let state_adt_ref = tcx.adt_def(state_did); - let state_substs = tcx.intern_substs(&[body.return_ty().into()]); - (state_adt_ref, state_substs) + let poll_did = tcx.require_lang_item(LangItem::Poll, None); + let poll_adt_ref = tcx.adt_def(poll_did); + let poll_substs = tcx.intern_substs(&[body.return_ty().into()]); + (poll_adt_ref, poll_substs) } else { // Compute GeneratorState<yield_ty, return_ty> let state_did = tcx.require_lang_item(LangItem::GeneratorState, None); @@ -1303,13 +1401,19 @@ impl<'tcx> MirPass<'tcx> for StateTransform { // RETURN_PLACE then is a fresh unused local with type ret_ty. let new_ret_local = replace_local(RETURN_PLACE, ret_ty, body, tcx); + // Replace all occurrences of `ResumeTy` with `&mut Context<'_>` within async bodies. + if is_async_kind { + transform_async_context(tcx, body); + } + // We also replace the resume argument and insert an `Assign`. // This is needed because the resume argument `_2` might be live across a `yield`, in which // case there is no `Assign` to it that the transform can turn into a store to the generator // state. After the yield the slot in the generator state would then be uninitialized. let resume_local = Local::new(2); - let new_resume_local = - replace_local(resume_local, body.local_decls[resume_local].ty, body, tcx); + let resume_ty = + if is_async_kind { tcx.mk_task_context() } else { body.local_decls[resume_local].ty }; + let new_resume_local = replace_local(resume_local, resume_ty, body, tcx); // When first entering the generator, move the resume argument into its new local. let source_info = SourceInfo::outermost(body.span); diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs index 706002f79b1..7597b8d126a 100644 --- a/compiler/rustc_span/src/symbol.rs +++ b/compiler/rustc_span/src/symbol.rs @@ -164,6 +164,7 @@ symbols! { Capture, Center, Clone, + Context, Continue, Copy, Count, diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs index 669f84ae1b4..91a505a72fa 100644 --- a/compiler/rustc_ty_utils/src/abi.rs +++ b/compiler/rustc_ty_utils/src/abi.rs @@ -108,21 +108,41 @@ fn fn_sig_for_fn_abi<'tcx>( // `Generator::resume(...) -> GeneratorState` function in case we // have an ordinary generator, or the `Future::poll(...) -> Poll` // function in case this is a special generator backing an async construct. - let ret_ty = if tcx.generator_is_async(did) { - let state_did = tcx.require_lang_item(LangItem::Poll, None); - let state_adt_ref = tcx.adt_def(state_did); - let state_substs = tcx.intern_substs(&[sig.return_ty.into()]); - tcx.mk_adt(state_adt_ref, state_substs) + let (resume_ty, ret_ty) = if tcx.generator_is_async(did) { + // The signature should be `Future::poll(_, &mut Context<'_>) -> Poll<Output>` + let poll_did = tcx.require_lang_item(LangItem::Poll, None); + let poll_adt_ref = tcx.adt_def(poll_did); + let poll_substs = tcx.intern_substs(&[sig.return_ty.into()]); + let ret_ty = tcx.mk_adt(poll_adt_ref, poll_substs); + + // We have to replace the `ResumeTy` that is used for type and borrow checking + // with `&mut Context<'_>` which is used in codegen. + #[cfg(debug_assertions)] + { + if let ty::Adt(resume_ty_adt, _) = sig.resume_ty.kind() { + let expected_adt = + tcx.adt_def(tcx.require_lang_item(LangItem::ResumeTy, None)); + assert_eq!(*resume_ty_adt, expected_adt); + } else { + panic!("expected `ResumeTy`, found `{:?}`", sig.resume_ty); + }; + } + let context_mut_ref = tcx.mk_task_context(); + + (context_mut_ref, ret_ty) } else { + // The signature should be `Generator::resume(_, Resume) -> GeneratorState<Yield, Return>` let state_did = tcx.require_lang_item(LangItem::GeneratorState, None); let state_adt_ref = tcx.adt_def(state_did); let state_substs = tcx.intern_substs(&[sig.yield_ty.into(), sig.return_ty.into()]); - tcx.mk_adt(state_adt_ref, state_substs) + let ret_ty = tcx.mk_adt(state_adt_ref, state_substs); + + (sig.resume_ty, ret_ty) }; ty::Binder::bind_with_vars( tcx.mk_fn_sig( - [env_ty, sig.resume_ty].iter(), + [env_ty, resume_ty].iter(), &ret_ty, false, hir::Unsafety::Normal, |