| //! The `Visitor` responsible for actually checking a `mir::Body` for invalid operations. |
| |
| use rustc_errors::struct_span_err; |
| use rustc_hir::{self as hir, lang_items}; |
| use rustc_hir::{def_id::DefId, HirId}; |
| use rustc_infer::infer::TyCtxtInferExt; |
| use rustc_middle::mir::visit::{MutatingUseContext, NonMutatingUseContext, PlaceContext, Visitor}; |
| use rustc_middle::mir::*; |
| use rustc_middle::ty::cast::CastTy; |
| use rustc_middle::ty::{self, Instance, InstanceDef, TyCtxt}; |
| use rustc_span::Span; |
| use rustc_trait_selection::traits::error_reporting::InferCtxtExt; |
| use rustc_trait_selection::traits::{self, TraitEngine}; |
| |
| use std::borrow::Cow; |
| use std::ops::Deref; |
| |
| use super::ops::{self, NonConstOp}; |
| use super::qualifs::{self, CustomEq, HasMutInterior, NeedsDrop}; |
| use super::resolver::FlowSensitiveAnalysis; |
| use super::{is_lang_panic_fn, ConstCx, Qualif}; |
| use crate::const_eval::{is_const_fn, is_unstable_const_fn}; |
| use crate::dataflow::impls::MaybeMutBorrowedLocals; |
| use crate::dataflow::{self, Analysis}; |
| |
| // We are using `MaybeMutBorrowedLocals` as a proxy for whether an item may have been mutated |
| // through a pointer prior to the given point. This is okay even though `MaybeMutBorrowedLocals` |
| // kills locals upon `StorageDead` because a local will never be used after a `StorageDead`. |
| type IndirectlyMutableResults<'mir, 'tcx> = |
| dataflow::ResultsCursor<'mir, 'tcx, MaybeMutBorrowedLocals<'mir, 'tcx>>; |
| |
| type QualifResults<'mir, 'tcx, Q> = |
| dataflow::ResultsCursor<'mir, 'tcx, FlowSensitiveAnalysis<'mir, 'mir, 'tcx, Q>>; |
| |
| #[derive(Default)] |
| pub struct Qualifs<'mir, 'tcx> { |
| has_mut_interior: Option<QualifResults<'mir, 'tcx, HasMutInterior>>, |
| needs_drop: Option<QualifResults<'mir, 'tcx, NeedsDrop>>, |
| indirectly_mutable: Option<IndirectlyMutableResults<'mir, 'tcx>>, |
| } |
| |
| impl Qualifs<'mir, 'tcx> { |
| pub fn indirectly_mutable( |
| &mut self, |
| ccx: &'mir ConstCx<'mir, 'tcx>, |
| local: Local, |
| location: Location, |
| ) -> bool { |
| let indirectly_mutable = self.indirectly_mutable.get_or_insert_with(|| { |
| let ConstCx { tcx, body, def_id, param_env, .. } = *ccx; |
| |
| // We can use `unsound_ignore_borrow_on_drop` here because custom drop impls are not |
| // allowed in a const. |
| // |
| // FIXME(ecstaticmorse): Someday we want to allow custom drop impls. How do we do this |
| // without breaking stable code? |
| MaybeMutBorrowedLocals::mut_borrows_only(tcx, &body, param_env) |
| .unsound_ignore_borrow_on_drop() |
| .into_engine(tcx, &body, def_id.to_def_id()) |
| .iterate_to_fixpoint() |
| .into_results_cursor(&body) |
| }); |
| |
| indirectly_mutable.seek_before_primary_effect(location); |
| indirectly_mutable.get().contains(local) |
| } |
| |
| /// Returns `true` if `local` is `NeedsDrop` at the given `Location`. |
| /// |
| /// Only updates the cursor if absolutely necessary |
| pub fn needs_drop( |
| &mut self, |
| ccx: &'mir ConstCx<'mir, 'tcx>, |
| local: Local, |
| location: Location, |
| ) -> bool { |
| let ty = ccx.body.local_decls[local].ty; |
| if !NeedsDrop::in_any_value_of_ty(ccx, ty) { |
| return false; |
| } |
| |
| let needs_drop = self.needs_drop.get_or_insert_with(|| { |
| let ConstCx { tcx, body, def_id, .. } = *ccx; |
| |
| FlowSensitiveAnalysis::new(NeedsDrop, ccx) |
| .into_engine(tcx, &body, def_id.to_def_id()) |
| .iterate_to_fixpoint() |
| .into_results_cursor(&body) |
| }); |
| |
| needs_drop.seek_before_primary_effect(location); |
| needs_drop.get().contains(local) || self.indirectly_mutable(ccx, local, location) |
| } |
| |
| /// Returns `true` if `local` is `HasMutInterior` at the given `Location`. |
| /// |
| /// Only updates the cursor if absolutely necessary. |
| pub fn has_mut_interior( |
| &mut self, |
| ccx: &'mir ConstCx<'mir, 'tcx>, |
| local: Local, |
| location: Location, |
| ) -> bool { |
| let ty = ccx.body.local_decls[local].ty; |
| if !HasMutInterior::in_any_value_of_ty(ccx, ty) { |
| return false; |
| } |
| |
| let has_mut_interior = self.has_mut_interior.get_or_insert_with(|| { |
| let ConstCx { tcx, body, def_id, .. } = *ccx; |
| |
| FlowSensitiveAnalysis::new(HasMutInterior, ccx) |
| .into_engine(tcx, &body, def_id.to_def_id()) |
| .iterate_to_fixpoint() |
| .into_results_cursor(&body) |
| }); |
| |
| has_mut_interior.seek_before_primary_effect(location); |
| has_mut_interior.get().contains(local) || self.indirectly_mutable(ccx, local, location) |
| } |
| |
| fn in_return_place(&mut self, ccx: &'mir ConstCx<'mir, '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 = ccx |
| .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(ccx, ccx.body.return_ty()), |
| Some(bb) => bb, |
| }; |
| |
| let return_loc = ccx.body.terminator_loc(return_block); |
| |
| let custom_eq = match ccx.const_kind() { |
| // We don't care whether a `const fn` returns a value that is not structurally |
| // matchable. Functions calls are opaque and always use type-based qualification, so |
| // this value should never be used. |
| hir::ConstContext::ConstFn => true, |
| |
| // If we know that all values of the return type are structurally matchable, there's no |
| // need to run dataflow. |
| _ if !CustomEq::in_any_value_of_ty(ccx, ccx.body.return_ty()) => false, |
| |
| hir::ConstContext::Const | hir::ConstContext::Static(_) => { |
| let mut cursor = FlowSensitiveAnalysis::new(CustomEq, ccx) |
| .into_engine(ccx.tcx, &ccx.body, ccx.def_id.to_def_id()) |
| .iterate_to_fixpoint() |
| .into_results_cursor(&ccx.body); |
| |
| cursor.seek_after_primary_effect(return_loc); |
| cursor.contains(RETURN_PLACE) |
| } |
| }; |
| |
| ConstQualifs { |
| needs_drop: self.needs_drop(ccx, RETURN_PLACE, return_loc), |
| has_mut_interior: self.has_mut_interior(ccx, RETURN_PLACE, return_loc), |
| custom_eq, |
| } |
| } |
| } |
| |
| pub struct Validator<'mir, 'tcx> { |
| ccx: &'mir ConstCx<'mir, 'tcx>, |
| qualifs: Qualifs<'mir, 'tcx>, |
| |
| /// The span of the current statement. |
| span: Span, |
| } |
| |
| impl Deref for Validator<'mir, 'tcx> { |
| type Target = ConstCx<'mir, 'tcx>; |
| |
| fn deref(&self) -> &Self::Target { |
| &self.ccx |
| } |
| } |
| |
| impl Validator<'mir, 'tcx> { |
| pub fn new(ccx: &'mir ConstCx<'mir, 'tcx>) -> Self { |
| Validator { span: ccx.body.span, ccx, qualifs: Default::default() } |
| } |
| |
| pub fn check_body(&mut self) { |
| let ConstCx { tcx, body, def_id, const_kind, .. } = *self.ccx; |
| |
| let use_min_const_fn_checks = (const_kind == Some(hir::ConstContext::ConstFn) |
| && crate::const_eval::is_min_const_fn(tcx, def_id.to_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.to_def_id(), &body) { |
| error_min_const_fn_violation(tcx, span, err); |
| return; |
| } |
| } |
| |
| 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(hir::ConstContext::Static(hir::Mutability::Not)) |
| && !tcx.is_thread_local_static(def_id.to_def_id()); |
| |
| if should_check_for_sync { |
| let hir_id = tcx.hir().as_local_hir_id(def_id); |
| check_return_ty_is_sync(tcx, &body, hir_id); |
| } |
| } |
| |
| pub fn qualifs_in_return_place(&mut self) -> ConstQualifs { |
| self.qualifs.in_return_place(self.ccx) |
| } |
| |
| /// Emits an error if an expression cannot be evaluated in the current context. |
| pub fn check_op(&mut self, op: impl NonConstOp) { |
| ops::non_const(self.ccx, op, self.span); |
| } |
| |
| /// Emits an error at the given `span` if an expression cannot be evaluated in the current |
| /// context. |
| pub fn check_op_spanned(&mut self, op: impl NonConstOp, span: Span) { |
| ops::non_const(self.ccx, op, span); |
| } |
| |
| fn check_static(&mut self, def_id: DefId, span: Span) { |
| assert!( |
| !self.tcx.is_thread_local_static(def_id), |
| "tls access is checked in `Rvalue::ThreadLocalRef" |
| ); |
| 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. |
| match *rvalue { |
| Rvalue::Ref(_, kind, place) => { |
| 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_local(&place.local, ctx, location); |
| self.visit_projection(place.local, reborrowed_proj, ctx, location); |
| return; |
| } |
| } |
| Rvalue::AddressOf(mutbl, place) => { |
| if let Some(reborrowed_proj) = place_as_reborrow(self.tcx, self.body, place) { |
| let ctx = match mutbl { |
| Mutability::Not => { |
| PlaceContext::NonMutatingUse(NonMutatingUseContext::AddressOf) |
| } |
| Mutability::Mut => PlaceContext::MutatingUse(MutatingUseContext::AddressOf), |
| }; |
| self.visit_local(&place.local, ctx, location); |
| self.visit_projection(place.local, reborrowed_proj, ctx, location); |
| return; |
| } |
| } |
| _ => {} |
| } |
| |
| self.super_rvalue(rvalue, location); |
| |
| match *rvalue { |
| Rvalue::ThreadLocalRef(_) => self.check_op(ops::ThreadLocalAccess), |
| |
| 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() == hir::ConstContext::Static(hir::Mutability::Mut) => |
| { |
| 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 { |
| if let BorrowKind::Mut { .. } = kind { |
| self.check_op(ops::MutBorrow); |
| } else { |
| self.check_op(ops::CellBorrow); |
| } |
| } |
| } |
| |
| Rvalue::AddressOf(Mutability::Mut, _) => self.check_op(ops::MutAddressOf), |
| |
| Rvalue::Ref(_, BorrowKind::Shared | BorrowKind::Shallow, ref place) |
| | Rvalue::AddressOf(Mutability::Not, ref place) => { |
| let borrowed_place_has_mut_interior = qualifs::in_place::<HasMutInterior, _>( |
| &self.ccx, |
| &mut |local| self.qualifs.has_mut_interior(self.ccx, local, location), |
| place.as_ref(), |
| ); |
| |
| if borrowed_place_has_mut_interior { |
| self.check_op(ops::CellBorrow); |
| } |
| } |
| |
| 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::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_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_local: Local, |
| proj_base: &[PlaceElem<'tcx>], |
| elem: PlaceElem<'tcx>, |
| context: PlaceContext, |
| location: Location, |
| ) { |
| trace!( |
| "visit_projection_elem: place_local={:?} proj_base={:?} elem={:?} \ |
| context={:?} location={:?}", |
| place_local, |
| proj_base, |
| elem, |
| context, |
| location, |
| ); |
| |
| self.super_projection_elem(place_local, proj_base, elem, context, location); |
| |
| match elem { |
| ProjectionElem::Deref => { |
| let base_ty = Place::ty_from(place_local, proj_base, self.body, self.tcx).ty; |
| if let ty::RawPtr(_) = base_ty.kind { |
| if proj_base.is_empty() { |
| if let (local, []) = (place_local, proj_base) { |
| let decl = &self.body.local_decls[local]; |
| if let Some(box 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::Downcast(..) |
| | ProjectionElem::Subslice { .. } |
| | ProjectionElem::Field(..) |
| | ProjectionElem::Index(_) => { |
| let base_ty = Place::ty_from(place_local, proj_base, self.body, self.tcx).ty; |
| match base_ty.ty_adt_def() { |
| Some(def) if def.is_union() => { |
| self.check_op(ops::UnionAccess); |
| } |
| |
| _ => {} |
| } |
| } |
| } |
| } |
| |
| 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::LlvmInlineAsm { .. } => { |
| self.super_statement(statement, location); |
| self.check_op(ops::InlineAsm); |
| } |
| |
| StatementKind::FakeRead(..) |
| | StatementKind::StorageLive(_) |
| | StatementKind::StorageDead(_) |
| | StatementKind::Retag { .. } |
| | StatementKind::AscribeUserType(..) |
| | StatementKind::Nop => {} |
| } |
| } |
| |
| fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) { |
| trace!("visit_terminator: terminator={:?} location={:?}", terminator, location); |
| self.super_terminator(terminator, location); |
| |
| match &terminator.kind { |
| TerminatorKind::Call { func, .. } => { |
| let fn_ty = func.ty(self.body, self.tcx); |
| |
| let (def_id, substs) = match fn_ty.kind { |
| ty::FnDef(def_id, substs) => (def_id, substs), |
| |
| ty::FnPtr(_) => { |
| self.check_op(ops::FnCallIndirect); |
| return; |
| } |
| _ => { |
| span_bug!(terminator.source_info.span, "invalid callee of type {:?}", fn_ty) |
| } |
| }; |
| |
| // At this point, we are calling a function whose `DefId` is known... |
| if is_const_fn(self.tcx, def_id) { |
| return; |
| } |
| |
| // See if this is a trait method for a concrete type whose impl of that trait is |
| // `const`. |
| if self.tcx.features().const_trait_impl { |
| let instance = Instance::resolve(self.tcx, self.param_env, def_id, substs); |
| debug!("Resolving ({:?}) -> {:?}", def_id, instance); |
| if let Ok(Some(func)) = instance { |
| if let InstanceDef::Item(def_id) = func.def { |
| if is_const_fn(self.tcx, def_id) { |
| return; |
| } |
| } |
| } |
| } |
| |
| if is_lang_panic_fn(self.tcx, def_id) { |
| self.check_op(ops::Panic); |
| } else if let Some(feature) = is_unstable_const_fn(self.tcx, def_id) { |
| // Exempt unstable const fns inside of macros or functions with |
| // `#[allow_internal_unstable]`. |
| use crate::transform::qualify_min_const_fn::lib_feature_allowed; |
| if !self.span.allows_unstable(feature) |
| && !lib_feature_allowed(self.tcx, self.def_id.to_def_id(), 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 { place: dropped_place, .. } |
| | TerminatorKind::DropAndReplace { place: dropped_place, .. } => { |
| // If we are checking live drops after drop-elaboration, don't emit duplicate |
| // errors here. |
| if super::post_drop_elaboration::checking_enabled(self.tcx) { |
| return; |
| } |
| |
| 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(self.ccx, local, location) |
| } else { |
| true |
| }; |
| |
| if needs_drop { |
| self.check_op_spanned( |
| ops::LiveDrop(Some(terminator.source_info.span)), |
| err_span, |
| ); |
| } |
| } |
| |
| TerminatorKind::InlineAsm { .. } => { |
| self.check_op(ops::InlineAsm); |
| } |
| |
| // FIXME: Some of these are only caught by `min_const_fn`, but should error here |
| // instead. |
| TerminatorKind::Abort |
| | TerminatorKind::Assert { .. } |
| | TerminatorKind::FalseEdge { .. } |
| | TerminatorKind::FalseUnwind { .. } |
| | TerminatorKind::GeneratorDrop |
| | TerminatorKind::Goto { .. } |
| | TerminatorKind::Resume |
| | TerminatorKind::Return |
| | TerminatorKind::SwitchInt { .. } |
| | TerminatorKind::Unreachable |
| | TerminatorKind::Yield { .. } => {} |
| } |
| } |
| } |
| |
| fn error_min_const_fn_violation(tcx: TyCtxt<'_>, span: Span, msg: Cow<'_, str>) { |
| struct_span_err!(tcx.sess, span, E0723, "{}", msg) |
| .note( |
| "see issue #57563 <https://github.com/rust-lang/rust/issues/57563> \ |
| for more information", |
| ) |
| .help("add `#![feature(const_fn)]` to the crate attributes to enable") |
| .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: 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 body.local_decls[place.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.local, inner, body, tcx).ty; |
| match inner_ty.kind { |
| ty::Ref(..) => Some(inner), |
| _ => None, |
| } |
| }) |
| } |
