diff options
Diffstat (limited to '')
| -rw-r--r-- | compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_build.rs (renamed from compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_build.rs) | 7 | ||||
| -rw-r--r-- | compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_propagate.rs (renamed from compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_propagate.rs) | 0 | ||||
| -rw-r--r-- | compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_visualize.rs (renamed from compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_visualize.rs) | 0 | ||||
| -rw-r--r-- | compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/record_consumed_borrow.rs (renamed from compiler/rustc_typeck/src/check/generator_interior/drop_ranges/record_consumed_borrow.rs) | 19 | ||||
| -rw-r--r-- | compiler/rustc_typeck/src/check/generator_interior.rs | 632 | ||||
| -rw-r--r-- | compiler/rustc_typeck/src/check/generator_interior/drop_ranges.rs | 309 |
6 files changed, 19 insertions, 948 deletions
diff --git a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_build.rs b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_build.rs index a2c23db16..122ad7009 100644 --- a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_build.rs +++ b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_build.rs @@ -210,7 +210,7 @@ impl<'a, 'tcx> DropRangeVisitor<'a, 'tcx> { } /// For an expression with an uninhabited return type (e.g. a function that returns !), - /// this adds a self edge to to the CFG to model the fact that the function does not + /// this adds a self edge to the CFG to model the fact that the function does not /// return. fn handle_uninhabited_return(&mut self, expr: &Expr<'tcx>) { let ty = self.typeck_results.expr_ty(expr); @@ -256,6 +256,8 @@ impl<'a, 'tcx> DropRangeVisitor<'a, 'tcx> { | hir::Node::TypeBinding(..) | hir::Node::TraitRef(..) | hir::Node::Pat(..) + | hir::Node::PatField(..) + | hir::Node::ExprField(..) | hir::Node::Arm(..) | hir::Node::Local(..) | hir::Node::Ctor(..) @@ -432,7 +434,8 @@ impl<'a, 'tcx> Visitor<'tcx> for DropRangeVisitor<'a, 'tcx> { self.handle_uninhabited_return(expr); } - ExprKind::MethodCall(_, exprs, _) => { + ExprKind::MethodCall(_, receiver, exprs, _) => { + self.visit_expr(receiver); for expr in exprs { self.visit_expr(expr); } diff --git a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_propagate.rs b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_propagate.rs index 139d17d2e..139d17d2e 100644 --- a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_propagate.rs +++ b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_propagate.rs diff --git a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_visualize.rs b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_visualize.rs index c0a0bfe8e..c0a0bfe8e 100644 --- a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_visualize.rs +++ b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_visualize.rs diff --git a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/record_consumed_borrow.rs b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/record_consumed_borrow.rs index ded0888c3..bfe95852a 100644 --- a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/record_consumed_borrow.rs +++ b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/record_consumed_borrow.rs @@ -1,13 +1,16 @@ use super::TrackedValue; use crate::{ - check::FnCtxt, expr_use_visitor::{self, ExprUseVisitor}, + FnCtxt, }; use hir::{def_id::DefId, Body, HirId, HirIdMap}; use rustc_data_structures::fx::FxHashSet; use rustc_hir as hir; -use rustc_middle::hir::place::{PlaceBase, Projection, ProjectionKind}; use rustc_middle::ty::{ParamEnv, TyCtxt}; +use rustc_middle::{ + hir::place::{PlaceBase, Projection, ProjectionKind}, + ty::TypeVisitable, +}; pub(super) fn find_consumed_and_borrowed<'a, 'tcx>( fcx: &'a FnCtxt<'a, 'tcx>, @@ -159,8 +162,8 @@ impl<'tcx> expr_use_visitor::Delegate<'tcx> for ExprUseDelegate<'tcx> { bk: rustc_middle::ty::BorrowKind, ) { debug!( - "borrow: place_with_id = {place_with_id:?}, diag_expr_id={diag_expr_id:?}, \ - borrow_kind={bk:?}" + "borrow: place_with_id = {place_with_id:#?}, diag_expr_id={diag_expr_id:#?}, \ + borrow_kind={bk:#?}" ); self.borrow_place(place_with_id); @@ -198,7 +201,13 @@ impl<'tcx> expr_use_visitor::Delegate<'tcx> for ExprUseDelegate<'tcx> { // If the type being assigned needs dropped, then the mutation counts as a borrow // since it is essentially doing `Drop::drop(&mut x); x = new_value;`. - if assignee_place.place.base_ty.needs_drop(self.tcx, self.param_env) { + let ty = self.tcx.erase_regions(assignee_place.place.base_ty); + if ty.needs_infer() { + self.tcx.sess.delay_span_bug( + self.tcx.hir().span(assignee_place.hir_id), + &format!("inference variables in {ty}"), + ); + } else if ty.needs_drop(self.tcx, self.param_env) { self.places .borrowed .insert(TrackedValue::from_place_with_projections_allowed(assignee_place)); diff --git a/compiler/rustc_typeck/src/check/generator_interior.rs b/compiler/rustc_typeck/src/check/generator_interior.rs deleted file mode 100644 index d4f800149..000000000 --- a/compiler/rustc_typeck/src/check/generator_interior.rs +++ /dev/null @@ -1,632 +0,0 @@ -//! This calculates the types which has storage which lives across a suspension point in a -//! generator from the perspective of typeck. The actual types used at runtime -//! is calculated in `rustc_mir_transform::generator` and may be a subset of the -//! types computed here. - -use self::drop_ranges::DropRanges; -use super::FnCtxt; -use rustc_data_structures::fx::{FxHashSet, FxIndexSet}; -use rustc_errors::pluralize; -use rustc_hir as hir; -use rustc_hir::def::{CtorKind, DefKind, Res}; -use rustc_hir::def_id::DefId; -use rustc_hir::hir_id::HirIdSet; -use rustc_hir::intravisit::{self, Visitor}; -use rustc_hir::{Arm, Expr, ExprKind, Guard, HirId, Pat, PatKind}; -use rustc_middle::middle::region::{self, Scope, ScopeData, YieldData}; -use rustc_middle::ty::{self, RvalueScopes, Ty, TyCtxt, TypeVisitable}; -use rustc_span::symbol::sym; -use rustc_span::Span; -use tracing::debug; - -mod drop_ranges; - -struct InteriorVisitor<'a, 'tcx> { - fcx: &'a FnCtxt<'a, 'tcx>, - region_scope_tree: &'a region::ScopeTree, - types: FxIndexSet<ty::GeneratorInteriorTypeCause<'tcx>>, - rvalue_scopes: &'a RvalueScopes, - expr_count: usize, - kind: hir::GeneratorKind, - prev_unresolved_span: Option<Span>, - linted_values: HirIdSet, - drop_ranges: DropRanges, -} - -impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> { - fn record( - &mut self, - ty: Ty<'tcx>, - hir_id: HirId, - scope: Option<region::Scope>, - expr: Option<&'tcx Expr<'tcx>>, - source_span: Span, - ) { - use rustc_span::DUMMY_SP; - - let ty = self.fcx.resolve_vars_if_possible(ty); - - debug!( - "attempting to record type ty={:?}; hir_id={:?}; scope={:?}; expr={:?}; source_span={:?}; expr_count={:?}", - ty, hir_id, scope, expr, source_span, self.expr_count, - ); - - let live_across_yield = scope - .map(|s| { - self.region_scope_tree.yield_in_scope(s).and_then(|yield_data| { - // If we are recording an expression that is the last yield - // in the scope, or that has a postorder CFG index larger - // than the one of all of the yields, then its value can't - // be storage-live (and therefore live) at any of the yields. - // - // See the mega-comment at `yield_in_scope` for a proof. - - yield_data - .iter() - .find(|yield_data| { - debug!( - "comparing counts yield: {} self: {}, source_span = {:?}", - yield_data.expr_and_pat_count, self.expr_count, source_span - ); - - if self.fcx.sess().opts.unstable_opts.drop_tracking - && self - .drop_ranges - .is_dropped_at(hir_id, yield_data.expr_and_pat_count) - { - debug!("value is dropped at yield point; not recording"); - return false; - } - - // If it is a borrowing happening in the guard, - // it needs to be recorded regardless because they - // do live across this yield point. - yield_data.expr_and_pat_count >= self.expr_count - }) - .cloned() - }) - }) - .unwrap_or_else(|| { - Some(YieldData { span: DUMMY_SP, expr_and_pat_count: 0, source: self.kind.into() }) - }); - - if let Some(yield_data) = live_across_yield { - debug!( - "type in expr = {:?}, scope = {:?}, type = {:?}, count = {}, yield_span = {:?}", - expr, scope, ty, self.expr_count, yield_data.span - ); - - if let Some((unresolved_type, unresolved_type_span)) = - self.fcx.unresolved_type_vars(&ty) - { - // If unresolved type isn't a ty_var then unresolved_type_span is None - let span = self - .prev_unresolved_span - .unwrap_or_else(|| unresolved_type_span.unwrap_or(source_span)); - - // If we encounter an int/float variable, then inference fallback didn't - // finish due to some other error. Don't emit spurious additional errors. - if let ty::Infer(ty::InferTy::IntVar(_) | ty::InferTy::FloatVar(_)) = - unresolved_type.kind() - { - self.fcx - .tcx - .sess - .delay_span_bug(span, &format!("Encountered var {:?}", unresolved_type)); - } else { - let note = format!( - "the type is part of the {} because of this {}", - self.kind, yield_data.source - ); - - self.fcx - .need_type_info_err_in_generator(self.kind, span, unresolved_type) - .span_note(yield_data.span, &*note) - .emit(); - } - } else { - // Insert the type into the ordered set. - let scope_span = scope.map(|s| s.span(self.fcx.tcx, self.region_scope_tree)); - - if !self.linted_values.contains(&hir_id) { - check_must_not_suspend_ty( - self.fcx, - ty, - hir_id, - SuspendCheckData { - expr, - source_span, - yield_span: yield_data.span, - plural_len: 1, - ..Default::default() - }, - ); - self.linted_values.insert(hir_id); - } - - self.types.insert(ty::GeneratorInteriorTypeCause { - span: source_span, - ty, - scope_span, - yield_span: yield_data.span, - expr: expr.map(|e| e.hir_id), - }); - } - } else { - debug!( - "no type in expr = {:?}, count = {:?}, span = {:?}", - expr, - self.expr_count, - expr.map(|e| e.span) - ); - if let Some((unresolved_type, unresolved_type_span)) = - self.fcx.unresolved_type_vars(&ty) - { - debug!( - "remained unresolved_type = {:?}, unresolved_type_span: {:?}", - unresolved_type, unresolved_type_span - ); - self.prev_unresolved_span = unresolved_type_span; - } - } - } -} - -pub fn resolve_interior<'a, 'tcx>( - fcx: &'a FnCtxt<'a, 'tcx>, - def_id: DefId, - body_id: hir::BodyId, - interior: Ty<'tcx>, - kind: hir::GeneratorKind, -) { - let body = fcx.tcx.hir().body(body_id); - let typeck_results = fcx.inh.typeck_results.borrow(); - let mut visitor = InteriorVisitor { - fcx, - types: FxIndexSet::default(), - region_scope_tree: fcx.tcx.region_scope_tree(def_id), - rvalue_scopes: &typeck_results.rvalue_scopes, - expr_count: 0, - kind, - prev_unresolved_span: None, - linted_values: <_>::default(), - drop_ranges: drop_ranges::compute_drop_ranges(fcx, def_id, body), - }; - intravisit::walk_body(&mut visitor, body); - - // Check that we visited the same amount of expressions as the RegionResolutionVisitor - let region_expr_count = fcx.tcx.region_scope_tree(def_id).body_expr_count(body_id).unwrap(); - assert_eq!(region_expr_count, visitor.expr_count); - - // The types are already kept in insertion order. - let types = visitor.types; - - // The types in the generator interior contain lifetimes local to the generator itself, - // which should not be exposed outside of the generator. Therefore, we replace these - // lifetimes with existentially-bound lifetimes, which reflect the exact value of the - // lifetimes not being known by users. - // - // These lifetimes are used in auto trait impl checking (for example, - // if a Sync generator contains an &'α T, we need to check whether &'α T: Sync), - // so knowledge of the exact relationships between them isn't particularly important. - - debug!("types in generator {:?}, span = {:?}", types, body.value.span); - - let mut counter = 0; - let mut captured_tys = FxHashSet::default(); - let type_causes: Vec<_> = types - .into_iter() - .filter_map(|mut cause| { - // Erase regions and canonicalize late-bound regions to deduplicate as many types as we - // can. - let erased = fcx.tcx.erase_regions(cause.ty); - if captured_tys.insert(erased) { - // Replace all regions inside the generator interior with late bound regions. - // Note that each region slot in the types gets a new fresh late bound region, - // which means that none of the regions inside relate to any other, even if - // typeck had previously found constraints that would cause them to be related. - let folded = fcx.tcx.fold_regions(erased, |_, current_depth| { - let br = ty::BoundRegion { - var: ty::BoundVar::from_u32(counter), - kind: ty::BrAnon(counter), - }; - let r = fcx.tcx.mk_region(ty::ReLateBound(current_depth, br)); - counter += 1; - r - }); - - cause.ty = folded; - Some(cause) - } else { - None - } - }) - .collect(); - - // Extract type components to build the witness type. - let type_list = fcx.tcx.mk_type_list(type_causes.iter().map(|cause| cause.ty)); - let bound_vars = fcx.tcx.mk_bound_variable_kinds( - (0..counter).map(|i| ty::BoundVariableKind::Region(ty::BrAnon(i))), - ); - let witness = - fcx.tcx.mk_generator_witness(ty::Binder::bind_with_vars(type_list, bound_vars.clone())); - - drop(typeck_results); - // Store the generator types and spans into the typeck results for this generator. - fcx.inh.typeck_results.borrow_mut().generator_interior_types = - ty::Binder::bind_with_vars(type_causes, bound_vars); - - debug!( - "types in generator after region replacement {:?}, span = {:?}", - witness, body.value.span - ); - - // Unify the type variable inside the generator with the new witness - match fcx.at(&fcx.misc(body.value.span), fcx.param_env).eq(interior, witness) { - Ok(ok) => fcx.register_infer_ok_obligations(ok), - _ => bug!(), - } -} - -// This visitor has to have the same visit_expr calls as RegionResolutionVisitor in -// librustc_middle/middle/region.rs since `expr_count` is compared against the results -// there. -impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> { - fn visit_arm(&mut self, arm: &'tcx Arm<'tcx>) { - let Arm { guard, pat, body, .. } = arm; - self.visit_pat(pat); - if let Some(ref g) = guard { - { - // If there is a guard, we need to count all variables bound in the pattern as - // borrowed for the entire guard body, regardless of whether they are accessed. - // We do this by walking the pattern bindings and recording `&T` for any `x: T` - // that is bound. - - struct ArmPatCollector<'a, 'b, 'tcx> { - interior_visitor: &'a mut InteriorVisitor<'b, 'tcx>, - scope: Scope, - } - - impl<'a, 'b, 'tcx> Visitor<'tcx> for ArmPatCollector<'a, 'b, 'tcx> { - fn visit_pat(&mut self, pat: &'tcx Pat<'tcx>) { - intravisit::walk_pat(self, pat); - if let PatKind::Binding(_, id, ident, ..) = pat.kind { - let ty = - self.interior_visitor.fcx.typeck_results.borrow().node_type(id); - let tcx = self.interior_visitor.fcx.tcx; - let ty = tcx.mk_ref( - // Use `ReErased` as `resolve_interior` is going to replace all the - // regions anyway. - tcx.mk_region(ty::ReErased), - ty::TypeAndMut { ty, mutbl: hir::Mutability::Not }, - ); - self.interior_visitor.record( - ty, - id, - Some(self.scope), - None, - ident.span, - ); - } - } - } - - ArmPatCollector { - interior_visitor: self, - scope: Scope { id: g.body().hir_id.local_id, data: ScopeData::Node }, - } - .visit_pat(pat); - } - - match g { - Guard::If(ref e) => { - self.visit_expr(e); - } - Guard::IfLet(ref l) => { - self.visit_let_expr(l); - } - } - } - self.visit_expr(body); - } - - fn visit_pat(&mut self, pat: &'tcx Pat<'tcx>) { - intravisit::walk_pat(self, pat); - - self.expr_count += 1; - - if let PatKind::Binding(..) = pat.kind { - let scope = self.region_scope_tree.var_scope(pat.hir_id.local_id).unwrap(); - let ty = self.fcx.typeck_results.borrow().pat_ty(pat); - self.record(ty, pat.hir_id, Some(scope), None, pat.span); - } - } - - fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) { - match &expr.kind { - ExprKind::Call(callee, args) => match &callee.kind { - ExprKind::Path(qpath) => { - let res = self.fcx.typeck_results.borrow().qpath_res(qpath, callee.hir_id); - match res { - // Direct calls never need to keep the callee `ty::FnDef` - // ZST in a temporary, so skip its type, just in case it - // can significantly complicate the generator type. - Res::Def( - DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(_, CtorKind::Fn), - _, - ) => { - // NOTE(eddyb) this assumes a path expression has - // no nested expressions to keep track of. - self.expr_count += 1; - - // Record the rest of the call expression normally. - for arg in *args { - self.visit_expr(arg); - } - } - _ => intravisit::walk_expr(self, expr), - } - } - _ => intravisit::walk_expr(self, expr), - }, - _ => intravisit::walk_expr(self, expr), - } - - self.expr_count += 1; - - debug!("is_borrowed_temporary: {:?}", self.drop_ranges.is_borrowed_temporary(expr)); - - let ty = self.fcx.typeck_results.borrow().expr_ty_adjusted_opt(expr); - let may_need_drop = |ty: Ty<'tcx>| { - // Avoid ICEs in needs_drop. - let ty = self.fcx.resolve_vars_if_possible(ty); - let ty = self.fcx.tcx.erase_regions(ty); - if ty.needs_infer() { - return true; - } - ty.needs_drop(self.fcx.tcx, self.fcx.param_env) - }; - - // Typically, the value produced by an expression is consumed by its parent in some way, - // so we only have to check if the parent contains a yield (note that the parent may, for - // example, store the value into a local variable, but then we already consider local - // variables to be live across their scope). - // - // However, in the case of temporary values, we are going to store the value into a - // temporary on the stack that is live for the current temporary scope and then return a - // reference to it. That value may be live across the entire temporary scope. - // - // There's another subtlety: if the type has an observable drop, it must be dropped after - // the yield, even if it's not borrowed or referenced after the yield. Ideally this would - // *only* happen for types with observable drop, not all types which wrap them, but that - // doesn't match the behavior of MIR borrowck and causes ICEs. See the FIXME comment in - // src/test/ui/generator/drop-tracking-parent-expression.rs. - let scope = if self.drop_ranges.is_borrowed_temporary(expr) - || ty.map_or(true, |ty| { - let needs_drop = may_need_drop(ty); - debug!(?needs_drop, ?ty); - needs_drop - }) { - self.rvalue_scopes.temporary_scope(self.region_scope_tree, expr.hir_id.local_id) - } else { - debug!("parent_node: {:?}", self.fcx.tcx.hir().find_parent_node(expr.hir_id)); - match self.fcx.tcx.hir().find_parent_node(expr.hir_id) { - Some(parent) => Some(Scope { id: parent.local_id, data: ScopeData::Node }), - None => { - self.rvalue_scopes.temporary_scope(self.region_scope_tree, expr.hir_id.local_id) - } - } - }; - - // If there are adjustments, then record the final type -- - // this is the actual value that is being produced. - if let Some(adjusted_ty) = ty { - self.record(adjusted_ty, expr.hir_id, scope, Some(expr), expr.span); - } - - // Also record the unadjusted type (which is the only type if - // there are no adjustments). The reason for this is that the - // unadjusted value is sometimes a "temporary" that would wind - // up in a MIR temporary. - // - // As an example, consider an expression like `vec![].push(x)`. - // Here, the `vec![]` would wind up MIR stored into a - // temporary variable `t` which we can borrow to invoke - // `<Vec<_>>::push(&mut t, x)`. - // - // Note that an expression can have many adjustments, and we - // are just ignoring those intermediate types. This is because - // those intermediate values are always linearly "consumed" by - // the other adjustments, and hence would never be directly - // captured in the MIR. - // - // (Note that this partly relies on the fact that the `Deref` - // traits always return references, which means their content - // can be reborrowed without needing to spill to a temporary. - // If this were not the case, then we could conceivably have - // to create intermediate temporaries.) - // - // The type table might not have information for this expression - // if it is in a malformed scope. (#66387) - if let Some(ty) = self.fcx.typeck_results.borrow().expr_ty_opt(expr) { - self.record(ty, expr.hir_id, scope, Some(expr), expr.span); - } else { - self.fcx.tcx.sess.delay_span_bug(expr.span, "no type for node"); - } - } -} - -#[derive(Default)] -pub struct SuspendCheckData<'a, 'tcx> { - expr: Option<&'tcx Expr<'tcx>>, - source_span: Span, - yield_span: Span, - descr_pre: &'a str, - descr_post: &'a str, - plural_len: usize, -} - -// Returns whether it emitted a diagnostic or not -// Note that this fn and the proceeding one are based on the code -// for creating must_use diagnostics -// -// Note that this technique was chosen over things like a `Suspend` marker trait -// as it is simpler and has precedent in the compiler -pub fn check_must_not_suspend_ty<'tcx>( - fcx: &FnCtxt<'_, 'tcx>, - ty: Ty<'tcx>, - hir_id: HirId, - data: SuspendCheckData<'_, 'tcx>, -) -> bool { - if ty.is_unit() - // FIXME: should this check `is_ty_uninhabited_from`. This query is not available in this stage - // of typeck (before ReVar and RePlaceholder are removed), but may remove noise, like in - // `must_use` - // || fcx.tcx.is_ty_uninhabited_from(fcx.tcx.parent_module(hir_id).to_def_id(), ty, fcx.param_env) - { - return false; - } - - let plural_suffix = pluralize!(data.plural_len); - - match *ty.kind() { - ty::Adt(..) if ty.is_box() => { - let boxed_ty = ty.boxed_ty(); - let descr_pre = &format!("{}boxed ", data.descr_pre); - check_must_not_suspend_ty(fcx, boxed_ty, hir_id, SuspendCheckData { descr_pre, ..data }) - } - ty::Adt(def, _) => check_must_not_suspend_def(fcx.tcx, def.did(), hir_id, data), - // FIXME: support adding the attribute to TAITs - ty::Opaque(def, _) => { - let mut has_emitted = false; - for &(predicate, _) in fcx.tcx.explicit_item_bounds(def) { - // We only look at the `DefId`, so it is safe to skip the binder here. - if let ty::PredicateKind::Trait(ref poly_trait_predicate) = - predicate.kind().skip_binder() - { - let def_id = poly_trait_predicate.trait_ref.def_id; - let descr_pre = &format!("{}implementer{} of ", data.descr_pre, plural_suffix); - if check_must_not_suspend_def( - fcx.tcx, - def_id, - hir_id, - SuspendCheckData { descr_pre, ..data }, - ) { - has_emitted = true; - break; - } - } - } - has_emitted - } - ty::Dynamic(binder, _) => { - let mut has_emitted = false; - for predicate in binder.iter() { - if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() { - let def_id = trait_ref.def_id; - let descr_post = &format!(" trait object{}{}", plural_suffix, data.descr_post); - if check_must_not_suspend_def( - fcx.tcx, - def_id, - hir_id, - SuspendCheckData { descr_post, ..data }, - ) { - has_emitted = true; - break; - } - } - } - has_emitted - } - ty::Tuple(fields) => { - let mut has_emitted = false; - let comps = match data.expr.map(|e| &e.kind) { - Some(hir::ExprKind::Tup(comps)) => { - debug_assert_eq!(comps.len(), fields.len()); - Some(comps) - } - _ => None, - }; - for (i, ty) in fields.iter().enumerate() { - let descr_post = &format!(" in tuple element {i}"); - let span = comps.and_then(|c| c.get(i)).map(|e| e.span).unwrap_or(data.source_span); - if check_must_not_suspend_ty( - fcx, - ty, - hir_id, - SuspendCheckData { - descr_post, - expr: comps.and_then(|comps| comps.get(i)), - source_span: span, - ..data - }, - ) { - has_emitted = true; - } - } - has_emitted - } - ty::Array(ty, len) => { - let descr_pre = &format!("{}array{} of ", data.descr_pre, plural_suffix); - check_must_not_suspend_ty( - fcx, - ty, - hir_id, - SuspendCheckData { - descr_pre, - plural_len: len.try_eval_usize(fcx.tcx, fcx.param_env).unwrap_or(0) as usize - + 1, - ..data - }, - ) - } - _ => false, - } -} - -fn check_must_not_suspend_def( - tcx: TyCtxt<'_>, - def_id: DefId, - hir_id: HirId, - data: SuspendCheckData<'_, '_>, -) -> bool { - if let Some(attr) = tcx.get_attr(def_id, sym::must_not_suspend) { - tcx.struct_span_lint_hir( - rustc_session::lint::builtin::MUST_NOT_SUSPEND, - hir_id, - data.source_span, - |lint| { - let msg = format!( - "{}`{}`{} held across a suspend point, but should not be", - data.descr_pre, - tcx.def_path_str(def_id), - data.descr_post, - ); - let mut err = lint.build(&msg); - - // add span pointing to the offending yield/await - err.span_label(data.yield_span, "the value is held across this suspend point"); - - // Add optional reason note - if let Some(note) = attr.value_str() { - // FIXME(guswynn): consider formatting this better - err.span_note(data.source_span, note.as_str()); - } - - // Add some quick suggestions on what to do - // FIXME: can `drop` work as a suggestion here as well? - err.span_help( - data.source_span, - "consider using a block (`{ ... }`) \ - to shrink the value's scope, ending before the suspend point", - ); - - err.emit(); - }, - ); - - true - } else { - false - } -} diff --git a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges.rs b/compiler/rustc_typeck/src/check/generator_interior/drop_ranges.rs deleted file mode 100644 index 518cd7342..000000000 --- a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges.rs +++ /dev/null @@ -1,309 +0,0 @@ -//! Drop range analysis finds the portions of the tree where a value is guaranteed to be dropped -//! (i.e. moved, uninitialized, etc.). This is used to exclude the types of those values from the -//! generator type. See `InteriorVisitor::record` for where the results of this analysis are used. -//! -//! There are three phases to this analysis: -//! 1. Use `ExprUseVisitor` to identify the interesting values that are consumed and borrowed. -//! 2. Use `DropRangeVisitor` to find where the interesting values are dropped or reinitialized, -//! and also build a control flow graph. -//! 3. Use `DropRanges::propagate_to_fixpoint` to flow the dropped/reinitialized information through -//! the CFG and find the exact points where we know a value is definitely dropped. -//! -//! The end result is a data structure that maps the post-order index of each node in the HIR tree -//! to a set of values that are known to be dropped at that location. - -use self::cfg_build::build_control_flow_graph; -use self::record_consumed_borrow::find_consumed_and_borrowed; -use crate::check::FnCtxt; -use hir::def_id::DefId; -use hir::{Body, HirId, HirIdMap, Node}; -use rustc_data_structures::fx::{FxHashMap, FxHashSet}; -use rustc_hir as hir; -use rustc_index::bit_set::BitSet; -use rustc_index::vec::IndexVec; -use rustc_middle::hir::map::Map; -use rustc_middle::hir::place::{PlaceBase, PlaceWithHirId}; -use rustc_middle::ty; -use std::collections::BTreeMap; -use std::fmt::Debug; - -mod cfg_build; -mod cfg_propagate; -mod cfg_visualize; -mod record_consumed_borrow; - -pub fn compute_drop_ranges<'a, 'tcx>( - fcx: &'a FnCtxt<'a, 'tcx>, - def_id: DefId, - body: &'tcx Body<'tcx>, -) -> DropRanges { - if fcx.sess().opts.unstable_opts.drop_tracking { - let consumed_borrowed_places = find_consumed_and_borrowed(fcx, def_id, body); - - let typeck_results = &fcx.typeck_results.borrow(); - let num_exprs = fcx.tcx.region_scope_tree(def_id).body_expr_count(body.id()).unwrap_or(0); - let (mut drop_ranges, borrowed_temporaries) = build_control_flow_graph( - fcx.tcx.hir(), - fcx.tcx, - typeck_results, - consumed_borrowed_places, - body, - num_exprs, - ); - - drop_ranges.propagate_to_fixpoint(); - - debug!("borrowed_temporaries = {borrowed_temporaries:?}"); - DropRanges { - tracked_value_map: drop_ranges.tracked_value_map, - nodes: drop_ranges.nodes, - borrowed_temporaries: Some(borrowed_temporaries), - } - } else { - // If drop range tracking is not enabled, skip all the analysis and produce an - // empty set of DropRanges. - DropRanges { - tracked_value_map: FxHashMap::default(), - nodes: IndexVec::new(), - borrowed_temporaries: None, - } - } -} - -/// Applies `f` to consumable node in the HIR subtree pointed to by `place`. -/// -/// This includes the place itself, and if the place is a reference to a local -/// variable then `f` is also called on the HIR node for that variable as well. -/// -/// For example, if `place` points to `foo()`, then `f` is called once for the -/// result of `foo`. On the other hand, if `place` points to `x` then `f` will -/// be called both on the `ExprKind::Path` node that represents the expression -/// as well as the HirId of the local `x` itself. -fn for_each_consumable<'tcx>(hir: Map<'tcx>, place: TrackedValue, mut f: impl FnMut(TrackedValue)) { - f(place); - let node = hir.find(place.hir_id()); - if let Some(Node::Expr(expr)) = node { - match expr.kind { - hir::ExprKind::Path(hir::QPath::Resolved( - _, - hir::Path { res: hir::def::Res::Local(hir_id), .. }, - )) => { - f(TrackedValue::Variable(*hir_id)); - } - _ => (), - } - } -} - -rustc_index::newtype_index! { - pub struct PostOrderId { - DEBUG_FORMAT = "id({})", - } -} - -rustc_index::newtype_index! { - pub struct TrackedValueIndex { - DEBUG_FORMAT = "hidx({})", - } -} - -/// Identifies a value whose drop state we need to track. -#[derive(PartialEq, Eq, Hash, Clone, Copy)] -enum TrackedValue { - /// Represents a named variable, such as a let binding, parameter, or upvar. - /// - /// The HirId points to the variable's definition site. - Variable(HirId), - /// A value produced as a result of an expression. - /// - /// The HirId points to the expression that returns this value. - Temporary(HirId), -} - -impl Debug for TrackedValue { - fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { - ty::tls::with_opt(|opt_tcx| { - if let Some(tcx) = opt_tcx { - write!(f, "{}", tcx.hir().node_to_string(self.hir_id())) - } else { - match self { - Self::Variable(hir_id) => write!(f, "Variable({:?})", hir_id), - Self::Temporary(hir_id) => write!(f, "Temporary({:?})", hir_id), - } - } - }) - } -} - -impl TrackedValue { - fn hir_id(&self) -> HirId { - match self { - TrackedValue::Variable(hir_id) | TrackedValue::Temporary(hir_id) => *hir_id, - } - } - - fn from_place_with_projections_allowed(place_with_id: &PlaceWithHirId<'_>) -> Self { - match place_with_id.place.base { - PlaceBase::Rvalue | PlaceBase::StaticItem => { - TrackedValue::Temporary(place_with_id.hir_id) - } - PlaceBase::Local(hir_id) - | PlaceBase::Upvar(ty::UpvarId { var_path: ty::UpvarPath { hir_id }, .. }) => { - TrackedValue::Variable(hir_id) - } - } - } -} - -/// Represents a reason why we might not be able to convert a HirId or Place -/// into a tracked value. -#[derive(Debug)] -enum TrackedValueConversionError { - /// Place projects are not currently supported. - /// - /// The reasoning around these is kind of subtle, so we choose to be more - /// conservative around these for now. There is no reason in theory we - /// cannot support these, we just have not implemented it yet. - PlaceProjectionsNotSupported, -} - -impl TryFrom<&PlaceWithHirId<'_>> for TrackedValue { - type Error = TrackedValueConversionError; - - fn try_from(place_with_id: &PlaceWithHirId<'_>) -> Result<Self, Self::Error> { - if !place_with_id.place.projections.is_empty() { - debug!( - "TrackedValue from PlaceWithHirId: {:?} has projections, which are not supported.", - place_with_id - ); - return Err(TrackedValueConversionError::PlaceProjectionsNotSupported); - } - - Ok(TrackedValue::from_place_with_projections_allowed(place_with_id)) - } -} - -pub struct DropRanges { - tracked_value_map: FxHashMap<TrackedValue, TrackedValueIndex>, - nodes: IndexVec<PostOrderId, NodeInfo>, - borrowed_temporaries: Option<FxHashSet<HirId>>, -} - -impl DropRanges { - pub fn is_dropped_at(&self, hir_id: HirId, location: usize) -> bool { - self.tracked_value_map - .get(&TrackedValue::Temporary(hir_id)) - .or(self.tracked_value_map.get(&TrackedValue::Variable(hir_id))) - .cloned() - .map_or(false, |tracked_value_id| { - self.expect_node(location.into()).drop_state.contains(tracked_value_id) - }) - } - - pub fn is_borrowed_temporary(&self, expr: &hir::Expr<'_>) -> bool { - if let Some(b) = &self.borrowed_temporaries { b.contains(&expr.hir_id) } else { true } - } - - /// Returns a reference to the NodeInfo for a node, panicking if it does not exist - fn expect_node(&self, id: PostOrderId) -> &NodeInfo { - &self.nodes[id] - } -} - -/// Tracks information needed to compute drop ranges. -struct DropRangesBuilder { - /// The core of DropRangesBuilder is a set of nodes, which each represent - /// one expression. We primarily refer to them by their index in a - /// post-order traversal of the HIR tree, since this is what - /// generator_interior uses to talk about yield positions. - /// - /// This IndexVec keeps the relevant details for each node. See the - /// NodeInfo struct for more details, but this information includes things - /// such as the set of control-flow successors, which variables are dropped - /// or reinitialized, and whether each variable has been inferred to be - /// known-dropped or potentially reinitialized at each point. - nodes: IndexVec<PostOrderId, NodeInfo>, - /// We refer to values whose drop state we are tracking by the HirId of - /// where they are defined. Within a NodeInfo, however, we store the - /// drop-state in a bit vector indexed by a HirIdIndex - /// (see NodeInfo::drop_state). The hir_id_map field stores the mapping - /// from HirIds to the HirIdIndex that is used to represent that value in - /// bitvector. - tracked_value_map: FxHashMap<TrackedValue, TrackedValueIndex>, - - /// When building the control flow graph, we don't always know the - /// post-order index of the target node at the point we encounter it. - /// For example, this happens with break and continue. In those cases, - /// we store a pair of the PostOrderId of the source and the HirId - /// of the target. Once we have gathered all of these edges, we make a - /// pass over the set of deferred edges (see process_deferred_edges in - /// cfg_build.rs), look up the PostOrderId for the target (since now the - /// post-order index for all nodes is known), and add missing control flow - /// edges. - deferred_edges: Vec<(PostOrderId, HirId)>, - /// This maps HirIds of expressions to their post-order index. It is - /// used in process_deferred_edges to correctly add back-edges. - post_order_map: HirIdMap<PostOrderId>, -} - -impl Debug for DropRangesBuilder { - fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { - f.debug_struct("DropRanges") - .field("hir_id_map", &self.tracked_value_map) - .field("post_order_maps", &self.post_order_map) - .field("nodes", &self.nodes.iter_enumerated().collect::<BTreeMap<_, _>>()) - .finish() - } -} - -/// DropRanges keeps track of what values are definitely dropped at each point in the code. -/// -/// Values of interest are defined by the hir_id of their place. Locations in code are identified -/// by their index in the post-order traversal. At its core, DropRanges maps -/// (hir_id, post_order_id) -> bool, where a true value indicates that the value is definitely -/// dropped at the point of the node identified by post_order_id. -impl DropRangesBuilder { - /// Returns the number of values (hir_ids) that are tracked - fn num_values(&self) -> usize { - self.tracked_value_map.len() - } - - fn node_mut(&mut self, id: PostOrderId) -> &mut NodeInfo { - let size = self.num_values(); - self.nodes.ensure_contains_elem(id, || NodeInfo::new(size)); - &mut self.nodes[id] - } - - fn add_control_edge(&mut self, from: PostOrderId, to: PostOrderId) { - trace!("adding control edge from {:?} to {:?}", from, to); - self.node_mut(from).successors.push(to); - } -} - -#[derive(Debug)] -struct NodeInfo { - /// IDs of nodes that can follow this one in the control flow - /// - /// If the vec is empty, then control proceeds to the next node. - successors: Vec<PostOrderId>, - - /// List of hir_ids that are dropped by this node. - drops: Vec<TrackedValueIndex>, - - /// List of hir_ids that are reinitialized by this node. - reinits: Vec<TrackedValueIndex>, - - /// Set of values that are definitely dropped at this point. - drop_state: BitSet<TrackedValueIndex>, -} - -impl NodeInfo { - fn new(num_values: usize) -> Self { - Self { - successors: vec![], - drops: vec![], - reinits: vec![], - drop_state: BitSet::new_filled(num_values), - } - } -} |