| //! The `Visitor` responsible for actually checking a `mir::Body` for invalid operations. |
| |
| use rustc::hir::{HirId, def_id::DefId}; |
| use rustc::middle::lang_items; |
| use rustc::mir::visit::{PlaceContext, Visitor, MutatingUseContext, NonMutatingUseContext}; |
| use rustc::mir::*; |
| use rustc::traits::{self, TraitEngine}; |
| use rustc::ty::cast::CastTy; |
| use rustc::ty::{self, TyCtxt}; |
| use rustc_index::bit_set::BitSet; |
| use rustc_error_codes::*; |
| use syntax::symbol::sym; |
| use syntax_pos::Span; |
| |
| use std::borrow::Cow; |
| use std::ops::Deref; |
| |
| use crate::dataflow::{self as old_dataflow, generic as dataflow}; |
| use self::old_dataflow::IndirectlyMutableLocals; |
| use super::ops::{self, NonConstOp}; |
| use super::qualifs::{self, HasMutInterior, NeedsDrop}; |
| use super::resolver::FlowSensitiveAnalysis; |
| use super::{ConstKind, Item, Qualif, is_lang_panic_fn}; |
| |
| pub type IndirectlyMutableResults<'mir, 'tcx> = |
| old_dataflow::DataflowResultsCursor<'mir, 'tcx, IndirectlyMutableLocals<'mir, 'tcx>>; |
| |
| struct QualifCursor<'a, 'mir, 'tcx, Q: Qualif> { |
| cursor: dataflow::ResultsCursor<'mir, 'tcx, FlowSensitiveAnalysis<'a, 'mir, 'tcx, Q>>, |
| in_any_value_of_ty: BitSet<Local>, |
| } |
| |
| impl<Q: Qualif> QualifCursor<'a, 'mir, 'tcx, Q> { |
| pub fn new( |
| q: Q, |
| item: &'a Item<'mir, 'tcx>, |
| dead_unwinds: &BitSet<BasicBlock>, |
| ) -> Self { |
| let analysis = FlowSensitiveAnalysis::new(q, item); |
| let results = |
| dataflow::Engine::new(item.tcx, &item.body, item.def_id, dead_unwinds, analysis) |
| .iterate_to_fixpoint(); |
| let cursor = dataflow::ResultsCursor::new(item.body.body(), results); |
| |
| let mut in_any_value_of_ty = BitSet::new_empty(item.body.local_decls.len()); |
| for (local, decl) in item.body.local_decls.iter_enumerated() { |
| if Q::in_any_value_of_ty(item, decl.ty) { |
| in_any_value_of_ty.insert(local); |
| } |
| } |
| |
| QualifCursor { |
| cursor, |
| in_any_value_of_ty, |
| } |
| } |
| } |
| |
| pub struct Qualifs<'a, 'mir, 'tcx> { |
| has_mut_interior: QualifCursor<'a, 'mir, 'tcx, HasMutInterior>, |
| needs_drop: QualifCursor<'a, 'mir, 'tcx, NeedsDrop>, |
| indirectly_mutable: IndirectlyMutableResults<'mir, 'tcx>, |
| } |
| |
| impl Qualifs<'a, 'mir, 'tcx> { |
| fn indirectly_mutable(&mut self, local: Local, location: Location) -> bool { |
| self.indirectly_mutable.seek(location); |
| self.indirectly_mutable.get().contains(local) |
| } |
| |
| /// Returns `true` if `local` is `NeedsDrop` at the given `Location`. |
| /// |
| /// Only updates the cursor if absolutely necessary |
| fn needs_drop_lazy_seek(&mut self, local: Local, location: Location) -> bool { |
| if !self.needs_drop.in_any_value_of_ty.contains(local) { |
| return false; |
| } |
| |
| self.needs_drop.cursor.seek_before(location); |
| self.needs_drop.cursor.get().contains(local) |
| || self.indirectly_mutable(local, location) |
| } |
| |
| /// Returns `true` if `local` is `HasMutInterior` at the given `Location`. |
| /// |
| /// Only updates the cursor if absolutely necessary. |
| fn has_mut_interior_lazy_seek(&mut self, local: Local, location: Location) -> bool { |
| if !self.has_mut_interior.in_any_value_of_ty.contains(local) { |
| return false; |
| } |
| |
| self.has_mut_interior.cursor.seek_before(location); |
| self.has_mut_interior.cursor.get().contains(local) |
| || self.indirectly_mutable(local, location) |
| } |
| |
| /// Returns `true` if `local` is `HasMutInterior`, but requires the `has_mut_interior` and |
| /// `indirectly_mutable` cursors to be updated beforehand. |
| fn has_mut_interior_eager_seek(&self, local: Local) -> bool { |
| if !self.has_mut_interior.in_any_value_of_ty.contains(local) { |
| return false; |
| } |
| |
| self.has_mut_interior.cursor.get().contains(local) |
| || self.indirectly_mutable.get().contains(local) |
| } |
| |
| fn in_return_place(&mut self, item: &Item<'_, 'tcx>) -> ConstQualifs { |
| // Find the `Return` terminator if one exists. |
| // |
| // If no `Return` terminator exists, this MIR is divergent. Just return the conservative |
| // qualifs for the return type. |
| let return_block = item.body |
| .basic_blocks() |
| .iter_enumerated() |
| .find(|(_, block)| { |
| match block.terminator().kind { |
| TerminatorKind::Return => true, |
| _ => false, |
| } |
| }) |
| .map(|(bb, _)| bb); |
| |
| let return_block = match return_block { |
| None => return qualifs::in_any_value_of_ty(item, item.body.return_ty()), |
| Some(bb) => bb, |
| }; |
| |
| let return_loc = item.body.terminator_loc(return_block); |
| |
| ConstQualifs { |
| needs_drop: self.needs_drop_lazy_seek(RETURN_PLACE, return_loc), |
| has_mut_interior: self.has_mut_interior_lazy_seek(RETURN_PLACE, return_loc), |
| } |
| } |
| } |
| |
| pub struct Validator<'a, 'mir, 'tcx> { |
| item: &'a Item<'mir, 'tcx>, |
| qualifs: Qualifs<'a, 'mir, 'tcx>, |
| |
| /// The span of the current statement. |
| span: Span, |
| } |
| |
| impl Deref for Validator<'_, 'mir, 'tcx> { |
| type Target = Item<'mir, 'tcx>; |
| |
| fn deref(&self) -> &Self::Target { |
| &self.item |
| } |
| } |
| |
| impl Validator<'a, 'mir, 'tcx> { |
| pub fn new( |
| item: &'a Item<'mir, 'tcx>, |
| ) -> Self { |
| let dead_unwinds = BitSet::new_empty(item.body.basic_blocks().len()); |
| |
| let needs_drop = QualifCursor::new( |
| NeedsDrop, |
| item, |
| &dead_unwinds, |
| ); |
| |
| let has_mut_interior = QualifCursor::new( |
| HasMutInterior, |
| item, |
| &dead_unwinds, |
| ); |
| |
| let indirectly_mutable = old_dataflow::do_dataflow( |
| item.tcx, |
| &*item.body, |
| item.def_id, |
| &item.tcx.get_attrs(item.def_id), |
| &dead_unwinds, |
| old_dataflow::IndirectlyMutableLocals::new(item.tcx, item.body.body(), item.param_env), |
| |_, local| old_dataflow::DebugFormatted::new(&local), |
| ); |
| |
| let indirectly_mutable = old_dataflow::DataflowResultsCursor::new( |
| indirectly_mutable, |
| item.body.body(), |
| ); |
| |
| let qualifs = Qualifs { |
| needs_drop, |
| has_mut_interior, |
| indirectly_mutable, |
| }; |
| |
| Validator { |
| span: item.body.span, |
| item, |
| qualifs, |
| } |
| } |
| |
| pub fn check_body(&mut self) { |
| let Item { tcx, body, def_id, const_kind, .. } = *self.item; |
| |
| let use_min_const_fn_checks = |
| (const_kind == Some(ConstKind::ConstFn) && tcx.is_min_const_fn(def_id)) |
| && !tcx.sess.opts.debugging_opts.unleash_the_miri_inside_of_you; |
| |
| if use_min_const_fn_checks { |
| // Enforce `min_const_fn` for stable `const fn`s. |
| use crate::transform::qualify_min_const_fn::is_min_const_fn; |
| if let Err((span, err)) = is_min_const_fn(tcx, def_id, &body) { |
| error_min_const_fn_violation(tcx, span, err); |
| return; |
| } |
| } |
| |
| check_short_circuiting_in_const_local(self.item); |
| |
| if body.is_cfg_cyclic() { |
| // We can't provide a good span for the error here, but this should be caught by the |
| // HIR const-checker anyways. |
| self.check_op_spanned(ops::Loop, body.span); |
| } |
| |
| self.visit_body(body); |
| |
| // Ensure that the end result is `Sync` in a non-thread local `static`. |
| let should_check_for_sync = const_kind == Some(ConstKind::Static) |
| && !tcx.has_attr(def_id, sym::thread_local); |
| |
| if should_check_for_sync { |
| let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap(); |
| check_return_ty_is_sync(tcx, &body, hir_id); |
| } |
| } |
| |
| pub fn qualifs_in_return_place(&mut self) -> ConstQualifs { |
| self.qualifs.in_return_place(self.item) |
| } |
| |
| /// Emits an error at the given `span` if an expression cannot be evaluated in the current |
| /// context. |
| pub fn check_op_spanned<O>(&mut self, op: O, span: Span) |
| where |
| O: NonConstOp |
| { |
| trace!("check_op: op={:?}", op); |
| |
| if op.is_allowed_in_item(self) { |
| return; |
| } |
| |
| // If an operation is supported in miri (and is not already controlled by a feature gate) it |
| // can be turned on with `-Zunleash-the-miri-inside-of-you`. |
| let is_unleashable = O::IS_SUPPORTED_IN_MIRI |
| && O::feature_gate(self.tcx).is_none(); |
| |
| if is_unleashable && self.tcx.sess.opts.debugging_opts.unleash_the_miri_inside_of_you { |
| self.tcx.sess.span_warn(span, "skipping const checks"); |
| return; |
| } |
| |
| op.emit_error(self, span); |
| } |
| |
| /// Emits an error if an expression cannot be evaluated in the current context. |
| pub fn check_op(&mut self, op: impl NonConstOp) { |
| let span = self.span; |
| self.check_op_spanned(op, span) |
| } |
| |
| fn check_static(&mut self, def_id: DefId, span: Span) { |
| let is_thread_local = self.tcx.has_attr(def_id, sym::thread_local); |
| if is_thread_local { |
| self.check_op_spanned(ops::ThreadLocalAccess, span) |
| } else { |
| self.check_op_spanned(ops::StaticAccess, span) |
| } |
| } |
| } |
| |
| impl Visitor<'tcx> for Validator<'_, 'mir, 'tcx> { |
| fn visit_basic_block_data( |
| &mut self, |
| bb: BasicBlock, |
| block: &BasicBlockData<'tcx>, |
| ) { |
| trace!("visit_basic_block_data: bb={:?} is_cleanup={:?}", bb, block.is_cleanup); |
| |
| // Just as the old checker did, we skip const-checking basic blocks on the unwind path. |
| // These blocks often drop locals that would otherwise be returned from the function. |
| // |
| // FIXME: This shouldn't be unsound since a panic at compile time will cause a compiler |
| // error anyway, but maybe we should do more here? |
| if block.is_cleanup { |
| return; |
| } |
| |
| self.super_basic_block_data(bb, block); |
| } |
| |
| fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) { |
| trace!("visit_rvalue: rvalue={:?} location={:?}", rvalue, location); |
| |
| // Special-case reborrows to be more like a copy of a reference. |
| if let Rvalue::Ref(_, kind, ref place) = *rvalue { |
| if let Some(reborrowed_proj) = place_as_reborrow(self.tcx, *self.body, place) { |
| let ctx = match kind { |
| BorrowKind::Shared => PlaceContext::NonMutatingUse( |
| NonMutatingUseContext::SharedBorrow, |
| ), |
| BorrowKind::Shallow => PlaceContext::NonMutatingUse( |
| NonMutatingUseContext::ShallowBorrow, |
| ), |
| BorrowKind::Unique => PlaceContext::NonMutatingUse( |
| NonMutatingUseContext::UniqueBorrow, |
| ), |
| BorrowKind::Mut { .. } => PlaceContext::MutatingUse( |
| MutatingUseContext::Borrow, |
| ), |
| }; |
| self.visit_place_base(&place.base, ctx, location); |
| self.visit_projection(&place.base, reborrowed_proj, ctx, location); |
| return; |
| } |
| } |
| |
| self.super_rvalue(rvalue, location); |
| |
| match *rvalue { |
| Rvalue::Use(_) | |
| Rvalue::Repeat(..) | |
| Rvalue::UnaryOp(UnOp::Neg, _) | |
| Rvalue::UnaryOp(UnOp::Not, _) | |
| Rvalue::NullaryOp(NullOp::SizeOf, _) | |
| Rvalue::CheckedBinaryOp(..) | |
| Rvalue::Cast(CastKind::Pointer(_), ..) | |
| Rvalue::Discriminant(..) | |
| Rvalue::Len(_) | |
| Rvalue::Aggregate(..) => {} |
| |
| | Rvalue::Ref(_, kind @ BorrowKind::Mut { .. }, ref place) |
| | Rvalue::Ref(_, kind @ BorrowKind::Unique, ref place) |
| => { |
| let ty = place.ty(*self.body, self.tcx).ty; |
| let is_allowed = match ty.kind { |
| // Inside a `static mut`, `&mut [...]` is allowed. |
| ty::Array(..) | ty::Slice(_) if self.const_kind() == ConstKind::StaticMut |
| => true, |
| |
| // FIXME(ecstaticmorse): We could allow `&mut []` inside a const context given |
| // that this is merely a ZST and it is already eligible for promotion. |
| // This may require an RFC? |
| /* |
| ty::Array(_, len) if len.try_eval_usize(cx.tcx, cx.param_env) == Some(0) |
| => true, |
| */ |
| |
| _ => false, |
| }; |
| |
| if !is_allowed { |
| self.check_op(ops::MutBorrow(kind)); |
| } |
| } |
| |
| // At the moment, `PlaceBase::Static` is only used for promoted MIR. |
| | Rvalue::Ref(_, BorrowKind::Shared, ref place) |
| | Rvalue::Ref(_, BorrowKind::Shallow, ref place) |
| if matches!(place.base, PlaceBase::Static(_)) |
| => bug!("Saw a promoted during const-checking, which must run before promotion"), |
| |
| | Rvalue::Ref(_, kind @ BorrowKind::Shared, ref place) |
| | Rvalue::Ref(_, kind @ BorrowKind::Shallow, ref place) |
| => { |
| // FIXME: Change the `in_*` methods to take a `FnMut` so we don't have to manually |
| // seek the cursors beforehand. |
| self.qualifs.has_mut_interior.cursor.seek_before(location); |
| self.qualifs.indirectly_mutable.seek(location); |
| |
| let borrowed_place_has_mut_interior = HasMutInterior::in_place( |
| &self.item, |
| &|local| self.qualifs.has_mut_interior_eager_seek(local), |
| place.as_ref(), |
| ); |
| |
| if borrowed_place_has_mut_interior { |
| self.check_op(ops::MutBorrow(kind)); |
| } |
| } |
| |
| Rvalue::Cast(CastKind::Misc, ref operand, cast_ty) => { |
| let operand_ty = operand.ty(*self.body, self.tcx); |
| let cast_in = CastTy::from_ty(operand_ty).expect("bad input type for cast"); |
| let cast_out = CastTy::from_ty(cast_ty).expect("bad output type for cast"); |
| |
| if let (CastTy::Ptr(_), CastTy::Int(_)) |
| | (CastTy::FnPtr, CastTy::Int(_)) = (cast_in, cast_out) { |
| self.check_op(ops::RawPtrToIntCast); |
| } |
| } |
| |
| Rvalue::BinaryOp(op, ref lhs, _) => { |
| if let ty::RawPtr(_) | ty::FnPtr(..) = lhs.ty(*self.body, self.tcx).kind { |
| assert!(op == BinOp::Eq || op == BinOp::Ne || |
| op == BinOp::Le || op == BinOp::Lt || |
| op == BinOp::Ge || op == BinOp::Gt || |
| op == BinOp::Offset); |
| |
| |
| self.check_op(ops::RawPtrComparison); |
| } |
| } |
| |
| Rvalue::NullaryOp(NullOp::Box, _) => { |
| self.check_op(ops::HeapAllocation); |
| } |
| } |
| } |
| |
| fn visit_place_base( |
| &mut self, |
| place_base: &PlaceBase<'tcx>, |
| context: PlaceContext, |
| location: Location, |
| ) { |
| trace!( |
| "visit_place_base: place_base={:?} context={:?} location={:?}", |
| place_base, |
| context, |
| location, |
| ); |
| self.super_place_base(place_base, context, location); |
| |
| match place_base { |
| PlaceBase::Local(_) => {} |
| PlaceBase::Static(_) => { |
| bug!("Promotion must be run after const validation"); |
| } |
| } |
| } |
| |
| fn visit_operand( |
| &mut self, |
| op: &Operand<'tcx>, |
| location: Location, |
| ) { |
| self.super_operand(op, location); |
| if let Operand::Constant(c) = op { |
| if let Some(def_id) = c.check_static_ptr(self.tcx) { |
| self.check_static(def_id, self.span); |
| } |
| } |
| } |
| |
| fn visit_projection_elem( |
| &mut self, |
| place_base: &PlaceBase<'tcx>, |
| proj_base: &[PlaceElem<'tcx>], |
| elem: &PlaceElem<'tcx>, |
| context: PlaceContext, |
| location: Location, |
| ) { |
| trace!( |
| "visit_projection_elem: place_base={:?} proj_base={:?} elem={:?} \ |
| context={:?} location={:?}", |
| place_base, |
| proj_base, |
| elem, |
| context, |
| location, |
| ); |
| |
| self.super_projection_elem(place_base, proj_base, elem, context, location); |
| |
| match elem { |
| ProjectionElem::Deref => { |
| let base_ty = Place::ty_from(place_base, proj_base, *self.body, self.tcx).ty; |
| if let ty::RawPtr(_) = base_ty.kind { |
| if proj_base.is_empty() { |
| if let (PlaceBase::Local(local), []) = (place_base, proj_base) { |
| let decl = &self.body.local_decls[*local]; |
| if let LocalInfo::StaticRef { def_id, .. } = decl.local_info { |
| let span = decl.source_info.span; |
| self.check_static(def_id, span); |
| return; |
| } |
| } |
| } |
| self.check_op(ops::RawPtrDeref); |
| } |
| |
| if context.is_mutating_use() { |
| self.check_op(ops::MutDeref); |
| } |
| } |
| |
| ProjectionElem::ConstantIndex {..} | |
| ProjectionElem::Subslice {..} | |
| ProjectionElem::Field(..) | |
| ProjectionElem::Index(_) => { |
| let base_ty = Place::ty_from(place_base, proj_base, *self.body, self.tcx).ty; |
| match base_ty.ty_adt_def() { |
| Some(def) if def.is_union() => { |
| self.check_op(ops::UnionAccess); |
| } |
| |
| _ => {} |
| } |
| } |
| |
| ProjectionElem::Downcast(..) => { |
| self.check_op(ops::Downcast); |
| } |
| } |
| } |
| |
| |
| fn visit_source_info(&mut self, source_info: &SourceInfo) { |
| trace!("visit_source_info: source_info={:?}", source_info); |
| self.span = source_info.span; |
| } |
| |
| fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) { |
| trace!("visit_statement: statement={:?} location={:?}", statement, location); |
| |
| match statement.kind { |
| StatementKind::Assign(..) | StatementKind::SetDiscriminant { .. } => { |
| self.super_statement(statement, location); |
| } |
| StatementKind::FakeRead(FakeReadCause::ForMatchedPlace, _) => { |
| self.check_op(ops::IfOrMatch); |
| } |
| // FIXME(eddyb) should these really do nothing? |
| StatementKind::FakeRead(..) | |
| StatementKind::StorageLive(_) | |
| StatementKind::StorageDead(_) | |
| StatementKind::InlineAsm {..} | |
| StatementKind::Retag { .. } | |
| StatementKind::AscribeUserType(..) | |
| StatementKind::Nop => {} |
| } |
| } |
| |
| fn visit_terminator_kind(&mut self, kind: &TerminatorKind<'tcx>, location: Location) { |
| trace!("visit_terminator_kind: kind={:?} location={:?}", kind, location); |
| self.super_terminator_kind(kind, location); |
| |
| match kind { |
| TerminatorKind::Call { func, .. } => { |
| let fn_ty = func.ty(*self.body, self.tcx); |
| |
| let def_id = match fn_ty.kind { |
| ty::FnDef(def_id, _) => def_id, |
| |
| ty::FnPtr(_) => { |
| self.check_op(ops::FnCallIndirect); |
| return; |
| } |
| _ => { |
| self.check_op(ops::FnCallOther); |
| return; |
| } |
| }; |
| |
| // At this point, we are calling a function whose `DefId` is known... |
| if self.tcx.is_const_fn(def_id) { |
| return; |
| } |
| |
| if is_lang_panic_fn(self.tcx, def_id) { |
| self.check_op(ops::Panic); |
| } else if let Some(feature) = self.tcx.is_unstable_const_fn(def_id) { |
| // Exempt unstable const fns inside of macros with |
| // `#[allow_internal_unstable]`. |
| if !self.span.allows_unstable(feature) { |
| self.check_op(ops::FnCallUnstable(def_id, feature)); |
| } |
| } else { |
| self.check_op(ops::FnCallNonConst(def_id)); |
| } |
| |
| } |
| |
| // Forbid all `Drop` terminators unless the place being dropped is a local with no |
| // projections that cannot be `NeedsDrop`. |
| | TerminatorKind::Drop { location: dropped_place, .. } |
| | TerminatorKind::DropAndReplace { location: dropped_place, .. } |
| => { |
| let mut err_span = self.span; |
| |
| // Check to see if the type of this place can ever have a drop impl. If not, this |
| // `Drop` terminator is frivolous. |
| let ty_needs_drop = dropped_place |
| .ty(*self.body, self.tcx) |
| .ty |
| .needs_drop(self.tcx, self.param_env); |
| |
| if !ty_needs_drop { |
| return; |
| } |
| |
| let needs_drop = if let Some(local) = dropped_place.as_local() { |
| // Use the span where the local was declared as the span of the drop error. |
| err_span = self.body.local_decls[local].source_info.span; |
| self.qualifs.needs_drop_lazy_seek(local, location) |
| } else { |
| true |
| }; |
| |
| if needs_drop { |
| self.check_op_spanned(ops::LiveDrop, err_span); |
| } |
| } |
| |
| _ => {} |
| } |
| } |
| } |
| |
| fn error_min_const_fn_violation(tcx: TyCtxt<'_>, span: Span, msg: Cow<'_, str>) { |
| struct_span_err!(tcx.sess, span, E0723, "{}", msg) |
| .note("for more information, see issue https://github.com/rust-lang/rust/issues/57563") |
| .help("add `#![feature(const_fn)]` to the crate attributes to enable") |
| .emit(); |
| } |
| |
| fn check_short_circuiting_in_const_local(item: &Item<'_, 'tcx>) { |
| let body = item.body; |
| |
| if body.control_flow_destroyed.is_empty() { |
| return; |
| } |
| |
| let mut locals = body.vars_iter(); |
| if let Some(local) = locals.next() { |
| let span = body.local_decls[local].source_info.span; |
| let mut error = item.tcx.sess.struct_span_err( |
| span, |
| &format!( |
| "new features like let bindings are not permitted in {}s \ |
| which also use short circuiting operators", |
| item.const_kind(), |
| ), |
| ); |
| for (span, kind) in body.control_flow_destroyed.iter() { |
| error.span_note( |
| *span, |
| &format!("use of {} here does not actually short circuit due to \ |
| the const evaluator presently not being able to do control flow. \ |
| See https://github.com/rust-lang/rust/issues/49146 for more \ |
| information.", kind), |
| ); |
| } |
| for local in locals { |
| let span = body.local_decls[local].source_info.span; |
| error.span_note(span, "more locals defined here"); |
| } |
| error.emit(); |
| } |
| } |
| |
| fn check_return_ty_is_sync(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, hir_id: HirId) { |
| let ty = body.return_ty(); |
| tcx.infer_ctxt().enter(|infcx| { |
| let cause = traits::ObligationCause::new(body.span, hir_id, traits::SharedStatic); |
| let mut fulfillment_cx = traits::FulfillmentContext::new(); |
| let sync_def_id = tcx.require_lang_item(lang_items::SyncTraitLangItem, Some(body.span)); |
| fulfillment_cx.register_bound(&infcx, ty::ParamEnv::empty(), ty, sync_def_id, cause); |
| if let Err(err) = fulfillment_cx.select_all_or_error(&infcx) { |
| infcx.report_fulfillment_errors(&err, None, false); |
| } |
| }); |
| } |
| |
| fn place_as_reborrow( |
| tcx: TyCtxt<'tcx>, |
| body: &Body<'tcx>, |
| place: &'a Place<'tcx>, |
| ) -> Option<&'a [PlaceElem<'tcx>]> { |
| place |
| .projection |
| .split_last() |
| .and_then(|(outermost, inner)| { |
| if outermost != &ProjectionElem::Deref { |
| return None; |
| } |
| |
| // A borrow of a `static` also looks like `&(*_1)` in the MIR, but `_1` is a `const` |
| // that points to the allocation for the static. Don't treat these as reborrows. |
| if let PlaceBase::Local(local) = place.base { |
| if body.local_decls[local].is_ref_to_static() { |
| return None; |
| } |
| } |
| |
| // Ensure the type being derefed is a reference and not a raw pointer. |
| // |
| // This is sufficient to prevent an access to a `static mut` from being marked as a |
| // reborrow, even if the check above were to disappear. |
| let inner_ty = Place::ty_from(&place.base, inner, body, tcx).ty; |
| match inner_ty.kind { |
| ty::Ref(..) => Some(inner), |
| _ => None, |
| } |
| }) |
| } |
