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-rw-r--r--compiler/rustc_mir_transform/src/check_unsafety.rs615
-rw-r--r--compiler/rustc_mir_transform/src/errors.rs171
-rw-r--r--compiler/rustc_mir_transform/src/lib.rs7
3 files changed, 2 insertions, 791 deletions
diff --git a/compiler/rustc_mir_transform/src/check_unsafety.rs b/compiler/rustc_mir_transform/src/check_unsafety.rs
deleted file mode 100644
index a0c3de3af58..00000000000
--- a/compiler/rustc_mir_transform/src/check_unsafety.rs
+++ /dev/null
@@ -1,615 +0,0 @@
-use rustc_data_structures::unord::{ExtendUnord, UnordItems, UnordSet};
-use rustc_hir as hir;
-use rustc_hir::def::DefKind;
-use rustc_hir::def_id::{DefId, LocalDefId};
-use rustc_hir::hir_id::HirId;
-use rustc_hir::intravisit;
-use rustc_hir::{BlockCheckMode, ExprKind, Node};
-use rustc_middle::mir::visit::{MutatingUseContext, PlaceContext, Visitor};
-use rustc_middle::mir::*;
-use rustc_middle::query::Providers;
-use rustc_middle::ty::{self, TyCtxt};
-use rustc_session::lint::builtin::{UNSAFE_OP_IN_UNSAFE_FN, UNUSED_UNSAFE};
-use rustc_session::lint::Level;
-
-use std::ops::Bound;
-
-use crate::errors;
-
-pub struct UnsafetyChecker<'a, 'tcx> {
-    body: &'a Body<'tcx>,
-    body_did: LocalDefId,
-    violations: Vec<UnsafetyViolation>,
-    source_info: SourceInfo,
-    tcx: TyCtxt<'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
-
-    /// Used `unsafe` blocks in this function. This is used for the "unused_unsafe" lint.
-    used_unsafe_blocks: UnordSet<HirId>,
-}
-
-impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
-    fn new(
-        body: &'a Body<'tcx>,
-        body_did: LocalDefId,
-        tcx: TyCtxt<'tcx>,
-        param_env: ty::ParamEnv<'tcx>,
-    ) -> Self {
-        Self {
-            body,
-            body_did,
-            violations: vec![],
-            source_info: SourceInfo::outermost(body.span),
-            tcx,
-            param_env,
-            used_unsafe_blocks: Default::default(),
-        }
-    }
-}
-
-impl<'tcx> Visitor<'tcx> for UnsafetyChecker<'_, 'tcx> {
-    fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
-        self.source_info = terminator.source_info;
-        match terminator.kind {
-            TerminatorKind::Goto { .. }
-            | TerminatorKind::SwitchInt { .. }
-            | TerminatorKind::Drop { .. }
-            | TerminatorKind::Yield { .. }
-            | TerminatorKind::Assert { .. }
-            | TerminatorKind::CoroutineDrop
-            | TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate(_)
-            | TerminatorKind::Return
-            | TerminatorKind::Unreachable
-            | TerminatorKind::FalseEdge { .. }
-            | TerminatorKind::FalseUnwind { .. } => {
-                // safe (at least as emitted during MIR construction)
-            }
-
-            TerminatorKind::Call { ref func, .. } => {
-                let func_ty = func.ty(self.body, self.tcx);
-                let func_id =
-                    if let ty::FnDef(func_id, _) = func_ty.kind() { Some(func_id) } else { None };
-                let sig = func_ty.fn_sig(self.tcx);
-                if let hir::Unsafety::Unsafe = sig.unsafety() {
-                    self.require_unsafe(
-                        UnsafetyViolationKind::General,
-                        UnsafetyViolationDetails::CallToUnsafeFunction,
-                    )
-                }
-
-                if let Some(func_id) = func_id {
-                    self.check_target_features(*func_id);
-                }
-            }
-
-            TerminatorKind::InlineAsm { .. } => self.require_unsafe(
-                UnsafetyViolationKind::General,
-                UnsafetyViolationDetails::UseOfInlineAssembly,
-            ),
-        }
-        self.super_terminator(terminator, location);
-    }
-
-    fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
-        self.source_info = statement.source_info;
-        match statement.kind {
-            StatementKind::Assign(..)
-            | StatementKind::FakeRead(..)
-            | StatementKind::SetDiscriminant { .. }
-            | StatementKind::Deinit(..)
-            | StatementKind::StorageLive(..)
-            | StatementKind::StorageDead(..)
-            | StatementKind::Retag { .. }
-            | StatementKind::PlaceMention(..)
-            | StatementKind::Coverage(..)
-            | StatementKind::Intrinsic(..)
-            | StatementKind::ConstEvalCounter
-            | StatementKind::Nop => {
-                // safe (at least as emitted during MIR construction)
-            }
-            // `AscribeUserType` just exists to help MIR borrowck.
-            // It has no semantics, and everything is already reported by `PlaceMention`.
-            StatementKind::AscribeUserType(..) => return,
-        }
-        self.super_statement(statement, location);
-    }
-
-    fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
-        match rvalue {
-            Rvalue::Aggregate(box ref aggregate, _) => match aggregate {
-                &AggregateKind::Array(..) | &AggregateKind::Tuple => {}
-                &AggregateKind::Adt(adt_did, ..) => {
-                    match self.tcx.layout_scalar_valid_range(adt_did) {
-                        (Bound::Unbounded, Bound::Unbounded) => {}
-                        _ => self.require_unsafe(
-                            UnsafetyViolationKind::General,
-                            UnsafetyViolationDetails::InitializingTypeWith,
-                        ),
-                    }
-                }
-                &AggregateKind::Closure(def_id, _)
-                | &AggregateKind::CoroutineClosure(def_id, _)
-                | &AggregateKind::Coroutine(def_id, _) => {
-                    let def_id = def_id.expect_local();
-                    let UnsafetyCheckResult { violations, used_unsafe_blocks, .. } =
-                        self.tcx.mir_unsafety_check_result(def_id);
-                    self.register_violations(violations, used_unsafe_blocks.items().copied());
-                }
-            },
-            _ => {}
-        }
-        self.super_rvalue(rvalue, location);
-    }
-
-    fn visit_operand(&mut self, op: &Operand<'tcx>, location: Location) {
-        if let Operand::Constant(constant) = op {
-            let maybe_uneval = match constant.const_ {
-                Const::Val(..) | Const::Ty(_) => None,
-                Const::Unevaluated(uv, _) => Some(uv),
-            };
-
-            if let Some(uv) = maybe_uneval {
-                if uv.promoted.is_none() {
-                    let def_id = uv.def;
-                    if self.tcx.def_kind(def_id) == DefKind::InlineConst {
-                        let local_def_id = def_id.expect_local();
-                        let UnsafetyCheckResult { violations, used_unsafe_blocks, .. } =
-                            self.tcx.mir_unsafety_check_result(local_def_id);
-                        self.register_violations(violations, used_unsafe_blocks.items().copied());
-                    }
-                }
-            }
-        }
-        self.super_operand(op, location);
-    }
-
-    fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, _location: Location) {
-        // On types with `scalar_valid_range`, prevent
-        // * `&mut x.field`
-        // * `x.field = y;`
-        // * `&x.field` if `field`'s type has interior mutability
-        // because either of these would allow modifying the layout constrained field and
-        // insert values that violate the layout constraints.
-        if context.is_mutating_use() || context.is_borrow() {
-            self.check_mut_borrowing_layout_constrained_field(*place, context.is_mutating_use());
-        }
-
-        // Some checks below need the extra meta info of the local declaration.
-        let decl = &self.body.local_decls[place.local];
-
-        // Check the base local: it might be an unsafe-to-access static. We only check derefs of the
-        // temporary holding the static pointer to avoid duplicate errors
-        // <https://github.com/rust-lang/rust/pull/78068#issuecomment-731753506>.
-        if place.projection.first() == Some(&ProjectionElem::Deref) {
-            // If the projection root is an artificial local that we introduced when
-            // desugaring `static`, give a more specific error message
-            // (avoid the general "raw pointer" clause below, that would only be confusing).
-            if let LocalInfo::StaticRef { def_id, .. } = *decl.local_info() {
-                if self.tcx.is_mutable_static(def_id) {
-                    self.require_unsafe(
-                        UnsafetyViolationKind::General,
-                        UnsafetyViolationDetails::UseOfMutableStatic,
-                    );
-                    return;
-                } else if self.tcx.is_foreign_item(def_id) {
-                    self.require_unsafe(
-                        UnsafetyViolationKind::General,
-                        UnsafetyViolationDetails::UseOfExternStatic,
-                    );
-                    return;
-                }
-            }
-        }
-
-        // Check for raw pointer `Deref`.
-        for (base, proj) in place.iter_projections() {
-            if proj == ProjectionElem::Deref {
-                let base_ty = base.ty(self.body, self.tcx).ty;
-                if base_ty.is_unsafe_ptr() {
-                    self.require_unsafe(
-                        UnsafetyViolationKind::General,
-                        UnsafetyViolationDetails::DerefOfRawPointer,
-                    )
-                }
-            }
-        }
-
-        // Check for union fields. For this we traverse right-to-left, as the last `Deref` changes
-        // whether we *read* the union field or potentially *write* to it (if this place is being assigned to).
-        let mut saw_deref = false;
-        for (base, proj) in place.iter_projections().rev() {
-            if proj == ProjectionElem::Deref {
-                saw_deref = true;
-                continue;
-            }
-
-            let base_ty = base.ty(self.body, self.tcx).ty;
-            if base_ty.is_union() {
-                // If we did not hit a `Deref` yet and the overall place use is an assignment, the
-                // rules are different.
-                let assign_to_field = !saw_deref
-                    && matches!(
-                        context,
-                        PlaceContext::MutatingUse(
-                            MutatingUseContext::Store
-                                | MutatingUseContext::Drop
-                                | MutatingUseContext::AsmOutput
-                        )
-                    );
-                // If this is just an assignment, determine if the assigned type needs dropping.
-                if assign_to_field {
-                    // We have to check the actual type of the assignment, as that determines if the
-                    // old value is being dropped.
-                    let assigned_ty = place.ty(&self.body.local_decls, self.tcx).ty;
-                    if assigned_ty.needs_drop(self.tcx, self.param_env) {
-                        // This would be unsafe, but should be outright impossible since we reject
-                        // such unions.
-                        assert!(
-                            self.tcx.dcx().has_errors().is_some(),
-                            "union fields that need dropping should be impossible: {assigned_ty}"
-                        );
-                    }
-                } else {
-                    self.require_unsafe(
-                        UnsafetyViolationKind::General,
-                        UnsafetyViolationDetails::AccessToUnionField,
-                    )
-                }
-            }
-        }
-    }
-}
-
-impl<'tcx> UnsafetyChecker<'_, 'tcx> {
-    fn require_unsafe(&mut self, kind: UnsafetyViolationKind, details: UnsafetyViolationDetails) {
-        // Violations can turn out to be `UnsafeFn` during analysis, but they should not start out as such.
-        assert_ne!(kind, UnsafetyViolationKind::UnsafeFn);
-
-        let source_info = self.source_info;
-        let lint_root = self.body.source_scopes[self.source_info.scope]
-            .local_data
-            .as_ref()
-            .assert_crate_local()
-            .lint_root;
-        self.register_violations(
-            [&UnsafetyViolation { source_info, lint_root, kind, details }],
-            UnordItems::empty(),
-        );
-    }
-
-    fn register_violations<'a>(
-        &mut self,
-        violations: impl IntoIterator<Item = &'a UnsafetyViolation>,
-        new_used_unsafe_blocks: UnordItems<HirId, impl Iterator<Item = HirId>>,
-    ) {
-        let safety = self.body.source_scopes[self.source_info.scope]
-            .local_data
-            .as_ref()
-            .assert_crate_local()
-            .safety;
-        match safety {
-            // `unsafe` blocks are required in safe code
-            Safety::Safe => violations.into_iter().for_each(|violation| {
-                match violation.kind {
-                    UnsafetyViolationKind::General => {}
-                    UnsafetyViolationKind::UnsafeFn => {
-                        bug!("`UnsafetyViolationKind::UnsafeFn` in an `Safe` context")
-                    }
-                }
-                if !self.violations.contains(violation) {
-                    self.violations.push(violation.clone())
-                }
-            }),
-            // With the RFC 2585, no longer allow `unsafe` operations in `unsafe fn`s
-            Safety::FnUnsafe => violations.into_iter().for_each(|violation| {
-                let mut violation = violation.clone();
-                violation.kind = UnsafetyViolationKind::UnsafeFn;
-                if !self.violations.contains(&violation) {
-                    self.violations.push(violation)
-                }
-            }),
-            Safety::BuiltinUnsafe => {}
-            Safety::ExplicitUnsafe(hir_id) => violations.into_iter().for_each(|_violation| {
-                self.used_unsafe_blocks.insert(hir_id);
-            }),
-        };
-
-        self.used_unsafe_blocks.extend_unord(new_used_unsafe_blocks);
-    }
-    fn check_mut_borrowing_layout_constrained_field(
-        &mut self,
-        place: Place<'tcx>,
-        is_mut_use: bool,
-    ) {
-        for (place_base, elem) in place.iter_projections().rev() {
-            match elem {
-                // Modifications behind a dereference don't affect the value of
-                // the pointer.
-                ProjectionElem::Deref => return,
-                ProjectionElem::Field(..) => {
-                    let ty = place_base.ty(&self.body.local_decls, self.tcx).ty;
-                    if let ty::Adt(def, _) = ty.kind() {
-                        if self.tcx.layout_scalar_valid_range(def.did())
-                            != (Bound::Unbounded, Bound::Unbounded)
-                        {
-                            let details = if is_mut_use {
-                                UnsafetyViolationDetails::MutationOfLayoutConstrainedField
-
-                            // Check `is_freeze` as late as possible to avoid cycle errors
-                            // with opaque types.
-                            } else if !place
-                                .ty(self.body, self.tcx)
-                                .ty
-                                .is_freeze(self.tcx, self.param_env)
-                            {
-                                UnsafetyViolationDetails::BorrowOfLayoutConstrainedField
-                            } else {
-                                continue;
-                            };
-                            self.require_unsafe(UnsafetyViolationKind::General, details);
-                        }
-                    }
-                }
-                _ => {}
-            }
-        }
-    }
-
-    /// Checks whether calling `func_did` needs an `unsafe` context or not, i.e. whether
-    /// the called function has target features the calling function hasn't.
-    fn check_target_features(&mut self, func_did: DefId) {
-        // Unsafety isn't required on wasm targets. For more information see
-        // the corresponding check in typeck/src/collect.rs
-        if self.tcx.sess.target.options.is_like_wasm {
-            return;
-        }
-
-        let callee_features = &self.tcx.codegen_fn_attrs(func_did).target_features;
-        // The body might be a constant, so it doesn't have codegen attributes.
-        let self_features = &self.tcx.body_codegen_attrs(self.body_did.to_def_id()).target_features;
-
-        // Is `callee_features` a subset of `calling_features`?
-        if !callee_features.iter().all(|feature| self_features.contains(feature)) {
-            let missing: Vec<_> = callee_features
-                .iter()
-                .copied()
-                .filter(|feature| !self_features.contains(feature))
-                .collect();
-            let build_enabled = self
-                .tcx
-                .sess
-                .target_features
-                .iter()
-                .copied()
-                .filter(|feature| missing.contains(feature))
-                .collect();
-            self.require_unsafe(
-                UnsafetyViolationKind::General,
-                UnsafetyViolationDetails::CallToFunctionWith { missing, build_enabled },
-            )
-        }
-    }
-}
-
-pub(crate) fn provide(providers: &mut Providers) {
-    *providers = Providers { mir_unsafety_check_result, ..*providers };
-}
-
-/// Context information for [`UnusedUnsafeVisitor`] traversal,
-/// saves (innermost) relevant context
-#[derive(Copy, Clone, Debug)]
-enum Context {
-    Safe,
-    /// in an `unsafe fn`
-    UnsafeFn,
-    /// in a *used* `unsafe` block
-    /// (i.e. a block without unused-unsafe warning)
-    UnsafeBlock(HirId),
-}
-
-struct UnusedUnsafeVisitor<'a, 'tcx> {
-    tcx: TyCtxt<'tcx>,
-    used_unsafe_blocks: &'a UnordSet<HirId>,
-    context: Context,
-    unused_unsafes: &'a mut Vec<(HirId, UnusedUnsafe)>,
-}
-
-impl<'tcx> intravisit::Visitor<'tcx> for UnusedUnsafeVisitor<'_, 'tcx> {
-    fn visit_block(&mut self, block: &'tcx hir::Block<'tcx>) {
-        if let hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::UserProvided) = block.rules {
-            let used = match self.tcx.lint_level_at_node(UNUSED_UNSAFE, block.hir_id) {
-                (Level::Allow, _) => true,
-                _ => self.used_unsafe_blocks.contains(&block.hir_id),
-            };
-            let unused_unsafe = match (self.context, used) {
-                (_, false) => UnusedUnsafe::Unused,
-                (Context::Safe, true) | (Context::UnsafeFn, true) => {
-                    let previous_context = self.context;
-                    self.context = Context::UnsafeBlock(block.hir_id);
-                    intravisit::walk_block(self, block);
-                    self.context = previous_context;
-                    return;
-                }
-                (Context::UnsafeBlock(hir_id), true) => UnusedUnsafe::InUnsafeBlock(hir_id),
-            };
-            self.unused_unsafes.push((block.hir_id, unused_unsafe));
-        }
-        intravisit::walk_block(self, block);
-    }
-
-    fn visit_inline_const(&mut self, c: &'tcx hir::ConstBlock) {
-        self.visit_body(self.tcx.hir().body(c.body))
-    }
-
-    fn visit_fn(
-        &mut self,
-        fk: intravisit::FnKind<'tcx>,
-        _fd: &'tcx hir::FnDecl<'tcx>,
-        b: hir::BodyId,
-        _s: rustc_span::Span,
-        _id: LocalDefId,
-    ) {
-        if matches!(fk, intravisit::FnKind::Closure) {
-            self.visit_body(self.tcx.hir().body(b))
-        }
-    }
-}
-
-fn check_unused_unsafe(
-    tcx: TyCtxt<'_>,
-    def_id: LocalDefId,
-    used_unsafe_blocks: &UnordSet<HirId>,
-) -> Vec<(HirId, UnusedUnsafe)> {
-    let body_id = tcx.hir().maybe_body_owned_by(def_id);
-
-    let Some(body_id) = body_id else {
-        debug!("check_unused_unsafe({:?}) - no body found", def_id);
-        return vec![];
-    };
-
-    let body = tcx.hir().body(body_id);
-    let hir_id = tcx.local_def_id_to_hir_id(def_id);
-    let context = match tcx.hir().fn_sig_by_hir_id(hir_id) {
-        Some(sig) if sig.header.unsafety == hir::Unsafety::Unsafe => Context::UnsafeFn,
-        _ => Context::Safe,
-    };
-
-    debug!(
-        "check_unused_unsafe({:?}, context={:?}, body={:?}, used_unsafe_blocks={:?})",
-        def_id, body, context, used_unsafe_blocks
-    );
-
-    let mut unused_unsafes = vec![];
-
-    let mut visitor = UnusedUnsafeVisitor {
-        tcx,
-        used_unsafe_blocks,
-        context,
-        unused_unsafes: &mut unused_unsafes,
-    };
-    intravisit::Visitor::visit_body(&mut visitor, body);
-
-    unused_unsafes
-}
-
-fn mir_unsafety_check_result(tcx: TyCtxt<'_>, def: LocalDefId) -> &UnsafetyCheckResult {
-    debug!("unsafety_violations({:?})", def);
-
-    // N.B., this borrow is valid because all the consumers of
-    // `mir_built` force this.
-    let body = &tcx.mir_built(def).borrow();
-
-    if body.is_custom_mir() || body.tainted_by_errors.is_some() {
-        return tcx.arena.alloc(UnsafetyCheckResult {
-            violations: Vec::new(),
-            used_unsafe_blocks: Default::default(),
-            unused_unsafes: Some(Vec::new()),
-        });
-    }
-
-    let param_env = tcx.param_env(def);
-
-    let mut checker = UnsafetyChecker::new(body, def, tcx, param_env);
-    checker.visit_body(body);
-
-    let unused_unsafes = (!tcx.is_typeck_child(def.to_def_id()))
-        .then(|| check_unused_unsafe(tcx, def, &checker.used_unsafe_blocks));
-
-    tcx.arena.alloc(UnsafetyCheckResult {
-        violations: checker.violations,
-        used_unsafe_blocks: checker.used_unsafe_blocks,
-        unused_unsafes,
-    })
-}
-
-fn report_unused_unsafe(tcx: TyCtxt<'_>, kind: UnusedUnsafe, id: HirId) {
-    let span = tcx.sess.source_map().guess_head_span(tcx.hir().span(id));
-    let nested_parent = if let UnusedUnsafe::InUnsafeBlock(id) = kind {
-        Some(tcx.sess.source_map().guess_head_span(tcx.hir().span(id)))
-    } else {
-        None
-    };
-    tcx.emit_node_span_lint(UNUSED_UNSAFE, id, span, errors::UnusedUnsafe { span, nested_parent });
-}
-
-pub fn check_unsafety(tcx: TyCtxt<'_>, def_id: LocalDefId) {
-    debug!("check_unsafety({:?})", def_id);
-
-    // closures and inline consts are handled by their parent fn.
-    if tcx.is_typeck_child(def_id.to_def_id()) {
-        return;
-    }
-
-    let UnsafetyCheckResult { violations, unused_unsafes, .. } =
-        tcx.mir_unsafety_check_result(def_id);
-    // Only suggest wrapping the entire function body in an unsafe block once
-    let mut suggest_unsafe_block = true;
-
-    for &UnsafetyViolation { source_info, lint_root, kind, ref details } in violations.iter() {
-        let details =
-            errors::RequiresUnsafeDetail { violation: details.clone(), span: source_info.span };
-
-        match kind {
-            UnsafetyViolationKind::General => {
-                let op_in_unsafe_fn_allowed = unsafe_op_in_unsafe_fn_allowed(tcx, lint_root);
-                let note_non_inherited = tcx.hir().parent_iter(lint_root).find(|(id, node)| {
-                    if let Node::Expr(block) = node
-                        && let ExprKind::Block(block, _) = block.kind
-                        && let BlockCheckMode::UnsafeBlock(_) = block.rules
-                    {
-                        true
-                    } else if let Some(sig) = tcx.hir().fn_sig_by_hir_id(*id)
-                        && sig.header.is_unsafe()
-                    {
-                        true
-                    } else {
-                        false
-                    }
-                });
-                let enclosing = if let Some((id, _)) = note_non_inherited {
-                    Some(tcx.sess.source_map().guess_head_span(tcx.hir().span(id)))
-                } else {
-                    None
-                };
-                tcx.dcx().emit_err(errors::RequiresUnsafe {
-                    span: source_info.span,
-                    enclosing,
-                    details,
-                    op_in_unsafe_fn_allowed,
-                });
-            }
-            UnsafetyViolationKind::UnsafeFn => {
-                tcx.emit_node_span_lint(
-                    UNSAFE_OP_IN_UNSAFE_FN,
-                    lint_root,
-                    source_info.span,
-                    errors::UnsafeOpInUnsafeFn {
-                        details,
-                        suggest_unsafe_block: suggest_unsafe_block.then(|| {
-                            let hir_id = tcx.local_def_id_to_hir_id(def_id);
-                            let fn_sig = tcx
-                                .hir()
-                                .fn_sig_by_hir_id(hir_id)
-                                .expect("this violation only occurs in fn");
-                            let body = tcx.hir().body_owned_by(def_id);
-                            let body_span = tcx.hir().body(body).value.span;
-                            let start = tcx.sess.source_map().start_point(body_span).shrink_to_hi();
-                            let end = tcx.sess.source_map().end_point(body_span).shrink_to_lo();
-                            (start, end, fn_sig.span)
-                        }),
-                    },
-                );
-                suggest_unsafe_block = false;
-            }
-        }
-    }
-
-    for &(block_id, kind) in unused_unsafes.as_ref().unwrap() {
-        report_unused_unsafe(tcx, kind, block_id);
-    }
-}
-
-fn unsafe_op_in_unsafe_fn_allowed(tcx: TyCtxt<'_>, id: HirId) -> bool {
-    tcx.lint_level_at_node(UNSAFE_OP_IN_UNSAFE_FN, id).0 == Level::Allow
-}
diff --git a/compiler/rustc_mir_transform/src/errors.rs b/compiler/rustc_mir_transform/src/errors.rs
index 9297bc51fad..0634e321ea3 100644
--- a/compiler/rustc_mir_transform/src/errors.rs
+++ b/compiler/rustc_mir_transform/src/errors.rs
@@ -1,11 +1,6 @@
-use std::borrow::Cow;
-
-use rustc_errors::{
-    codes::*, Applicability, Diag, DiagArgValue, DiagCtxt, DiagMessage, Diagnostic,
-    EmissionGuarantee, Level, LintDiagnostic,
-};
+use rustc_errors::{codes::*, Diag, DiagMessage, LintDiagnostic};
 use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
-use rustc_middle::mir::{AssertKind, UnsafetyViolationDetails};
+use rustc_middle::mir::AssertKind;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::lint::{self, Lint};
 use rustc_span::def_id::DefId;
@@ -42,168 +37,6 @@ pub(crate) struct UnalignedPackedRef {
     pub span: Span,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(mir_transform_unused_unsafe)]
-pub(crate) struct UnusedUnsafe {
-    #[label(mir_transform_unused_unsafe)]
-    pub span: Span,
-    #[label]
-    pub nested_parent: Option<Span>,
-}
-
-pub(crate) struct RequiresUnsafe {
-    pub span: Span,
-    pub details: RequiresUnsafeDetail,
-    pub enclosing: Option<Span>,
-    pub op_in_unsafe_fn_allowed: bool,
-}
-
-// The primary message for this diagnostic should be '{$label} is unsafe and...',
-// so we need to eagerly translate the label here, which isn't supported by the derive API
-// We could also exhaustively list out the primary messages for all unsafe violations,
-// but this would result in a lot of duplication.
-impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for RequiresUnsafe {
-    #[track_caller]
-    fn into_diag(self, dcx: &'a DiagCtxt, level: Level) -> Diag<'a, G> {
-        let mut diag = Diag::new(dcx, level, fluent::mir_transform_requires_unsafe);
-        diag.code(E0133);
-        diag.span(self.span);
-        diag.span_label(self.span, self.details.label());
-        let desc = dcx.eagerly_translate_to_string(self.details.label(), [].into_iter());
-        diag.arg("details", desc);
-        diag.arg("op_in_unsafe_fn_allowed", self.op_in_unsafe_fn_allowed);
-        self.details.add_subdiagnostics(&mut diag);
-        if let Some(sp) = self.enclosing {
-            diag.span_label(sp, fluent::mir_transform_not_inherited);
-        }
-        diag
-    }
-}
-
-#[derive(Clone)]
-pub(crate) struct RequiresUnsafeDetail {
-    pub span: Span,
-    pub violation: UnsafetyViolationDetails,
-}
-
-impl RequiresUnsafeDetail {
-    // FIXME: make this translatable
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
-    fn add_subdiagnostics<G: EmissionGuarantee>(&self, diag: &mut Diag<'_, G>) {
-        use UnsafetyViolationDetails::*;
-        match self.violation {
-            CallToUnsafeFunction => {
-                diag.note(fluent::mir_transform_call_to_unsafe_note);
-            }
-            UseOfInlineAssembly => {
-                diag.note(fluent::mir_transform_use_of_asm_note);
-            }
-            InitializingTypeWith => {
-                diag.note(fluent::mir_transform_initializing_valid_range_note);
-            }
-            CastOfPointerToInt => {
-                diag.note(fluent::mir_transform_const_ptr2int_note);
-            }
-            UseOfMutableStatic => {
-                diag.note(fluent::mir_transform_use_of_static_mut_note);
-            }
-            UseOfExternStatic => {
-                diag.note(fluent::mir_transform_use_of_extern_static_note);
-            }
-            DerefOfRawPointer => {
-                diag.note(fluent::mir_transform_deref_ptr_note);
-            }
-            AccessToUnionField => {
-                diag.note(fluent::mir_transform_union_access_note);
-            }
-            MutationOfLayoutConstrainedField => {
-                diag.note(fluent::mir_transform_mutation_layout_constrained_note);
-            }
-            BorrowOfLayoutConstrainedField => {
-                diag.note(fluent::mir_transform_mutation_layout_constrained_borrow_note);
-            }
-            CallToFunctionWith { ref missing, ref build_enabled } => {
-                diag.help(fluent::mir_transform_target_feature_call_help);
-                diag.arg(
-                    "missing_target_features",
-                    DiagArgValue::StrListSepByAnd(
-                        missing.iter().map(|feature| Cow::from(feature.to_string())).collect(),
-                    ),
-                );
-                diag.arg("missing_target_features_count", missing.len());
-                if !build_enabled.is_empty() {
-                    diag.note(fluent::mir_transform_target_feature_call_note);
-                    diag.arg(
-                        "build_target_features",
-                        DiagArgValue::StrListSepByAnd(
-                            build_enabled
-                                .iter()
-                                .map(|feature| Cow::from(feature.to_string()))
-                                .collect(),
-                        ),
-                    );
-                    diag.arg("build_target_features_count", build_enabled.len());
-                }
-            }
-        }
-    }
-
-    fn label(&self) -> DiagMessage {
-        use UnsafetyViolationDetails::*;
-        match self.violation {
-            CallToUnsafeFunction => fluent::mir_transform_call_to_unsafe_label,
-            UseOfInlineAssembly => fluent::mir_transform_use_of_asm_label,
-            InitializingTypeWith => fluent::mir_transform_initializing_valid_range_label,
-            CastOfPointerToInt => fluent::mir_transform_const_ptr2int_label,
-            UseOfMutableStatic => fluent::mir_transform_use_of_static_mut_label,
-            UseOfExternStatic => fluent::mir_transform_use_of_extern_static_label,
-            DerefOfRawPointer => fluent::mir_transform_deref_ptr_label,
-            AccessToUnionField => fluent::mir_transform_union_access_label,
-            MutationOfLayoutConstrainedField => {
-                fluent::mir_transform_mutation_layout_constrained_label
-            }
-            BorrowOfLayoutConstrainedField => {
-                fluent::mir_transform_mutation_layout_constrained_borrow_label
-            }
-            CallToFunctionWith { .. } => fluent::mir_transform_target_feature_call_label,
-        }
-    }
-}
-
-pub(crate) struct UnsafeOpInUnsafeFn {
-    pub details: RequiresUnsafeDetail,
-
-    /// These spans point to:
-    ///  1. the start of the function body
-    ///  2. the end of the function body
-    ///  3. the function signature
-    pub suggest_unsafe_block: Option<(Span, Span, Span)>,
-}
-
-impl<'a> LintDiagnostic<'a, ()> for UnsafeOpInUnsafeFn {
-    #[track_caller]
-    fn decorate_lint<'b>(self, diag: &'b mut Diag<'a, ()>) {
-        let desc = diag.dcx.eagerly_translate_to_string(self.details.label(), [].into_iter());
-        diag.arg("details", desc);
-        diag.span_label(self.details.span, self.details.label());
-        self.details.add_subdiagnostics(diag);
-
-        if let Some((start, end, fn_sig)) = self.suggest_unsafe_block {
-            diag.span_note(fn_sig, fluent::mir_transform_note);
-            diag.tool_only_multipart_suggestion(
-                fluent::mir_transform_suggestion,
-                vec![(start, " unsafe {".into()), (end, "}".into())],
-                Applicability::MaybeIncorrect,
-            );
-        }
-    }
-
-    fn msg(&self) -> DiagMessage {
-        fluent::mir_transform_unsafe_op_in_unsafe_fn
-    }
-}
-
 pub(crate) struct AssertLint<P> {
     pub span: Span,
     pub assert_kind: AssertKind<P>,
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
index a684f9bdff1..e477c068229 100644
--- a/compiler/rustc_mir_transform/src/lib.rs
+++ b/compiler/rustc_mir_transform/src/lib.rs
@@ -53,7 +53,6 @@ mod add_moves_for_packed_drops;
 mod add_retag;
 mod check_const_item_mutation;
 mod check_packed_ref;
-pub mod check_unsafety;
 mod remove_place_mention;
 // This pass is public to allow external drivers to perform MIR cleanup
 mod add_subtyping_projections;
@@ -120,7 +119,6 @@ use rustc_mir_dataflow::rustc_peek;
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 
 pub fn provide(providers: &mut Providers) {
-    check_unsafety::provide(providers);
     coverage::query::provide(providers);
     ffi_unwind_calls::provide(providers);
     shim::provide(providers);
@@ -280,11 +278,6 @@ fn mir_const_qualif(tcx: TyCtxt<'_>, def: LocalDefId) -> ConstQualifs {
 }
 
 fn mir_built(tcx: TyCtxt<'_>, def: LocalDefId) -> &Steal<Body<'_>> {
-    // MIR unsafety check uses the raw mir, so make sure it is run.
-    if !tcx.sess.opts.unstable_opts.thir_unsafeck {
-        tcx.ensure_with_value().mir_unsafety_check_result(def);
-    }
-
     let mut body = tcx.build_mir(def);
 
     pass_manager::dump_mir_for_phase_change(tcx, &body);