Auto merge of rust-lang#123322 - matthewjasper:remove-mir-unsafeck, r=lcnr,compiler-errors

Remove MIR unsafe check

Now that THIR unsafeck is enabled by default in stable I think we can remove MIR unsafeck entirely. This PR also removes safety information from MIR.

Author: bors

compiler/rustc_interface/src/passes.rs

@@ -748,9 +748,6 @@ fn analysis(tcx: TyCtxt<'_>, (): ()) -> Result<()> {
 
     sess.time("MIR_effect_checking", || {
         for def_id in tcx.hir().body_owners() {
-            if !tcx.sess.opts.unstable_opts.thir_unsafeck {
-                rustc_mir_transform::check_unsafety::check_unsafety(tcx, def_id);
-            }
             tcx.ensure().has_ffi_unwind_calls(def_id);
 
             // If we need to codegen, ensure that we emit all errors from

compiler/rustc_interface/src/tests.rs

@@ -840,7 +840,6 @@ fn test_unstable_options_tracking_hash() {
     tracked!(stack_protector, StackProtector::All);
     tracked!(teach, true);
     tracked!(thinlto, Some(true));
-    tracked!(thir_unsafeck, false);
     tracked!(tiny_const_eval_limit, true);
     tracked!(tls_model, Some(TlsModel::GeneralDynamic));
     tracked!(translate_remapped_path_to_local_path, false);

compiler/rustc_middle/src/arena.rs

@@ -35,7 +35,6 @@ macro_rules! arena_types {
             )>,
             [] crate_for_resolver: rustc_data_structures::steal::Steal<(rustc_ast::Crate, rustc_ast::AttrVec)>,
             [] resolutions: rustc_middle::ty::ResolverGlobalCtxt,
-            [decode] unsafety_check_result: rustc_middle::mir::UnsafetyCheckResult,
             [decode] code_region: rustc_middle::mir::coverage::CodeRegion,
             [] const_allocs: rustc_middle::mir::interpret::Allocation,
             [] region_scope_tree: rustc_middle::middle::region::ScopeTree,

compiler/rustc_middle/src/mir/mod.rs

@@ -845,17 +845,6 @@ impl<'tcx> Body<'tcx> {
     }
 }
 
-#[derive(Copy, Clone, PartialEq, Eq, Debug, TyEncodable, TyDecodable, HashStable)]
-pub enum Safety {
-    Safe,
-    /// Unsafe because of compiler-generated unsafe code, like `await` desugaring
-    BuiltinUnsafe,
-    /// Unsafe because of an unsafe fn
-    FnUnsafe,
-    /// Unsafe because of an `unsafe` block
-    ExplicitUnsafe(hir::HirId),
-}
-
 impl<'tcx> Index<BasicBlock> for Body<'tcx> {
     type Output = BasicBlockData<'tcx>;
 
@@ -1611,8 +1600,6 @@ pub struct SourceScopeData<'tcx> {
 pub struct SourceScopeLocalData {
     /// An `HirId` with lint levels equivalent to this scope's lint levels.
     pub lint_root: hir::HirId,
-    /// The unsafe block that contains this node.
-    pub safety: Safety,
 }
 
 /// A collection of projections into user types.
@@ -1888,7 +1875,7 @@ mod size_asserts {
     // tidy-alphabetical-start
     static_assert_size!(BasicBlockData<'_>, 144);
     static_assert_size!(LocalDecl<'_>, 40);
-    static_assert_size!(SourceScopeData<'_>, 72);
+    static_assert_size!(SourceScopeData<'_>, 64);
     static_assert_size!(Statement<'_>, 32);
     static_assert_size!(StatementKind<'_>, 16);
     static_assert_size!(Terminator<'_>, 112);

compiler/rustc_middle/src/mir/query.rs

@@ -3,9 +3,7 @@
 use crate::mir;
 use crate::ty::{self, OpaqueHiddenType, Ty, TyCtxt};
 use rustc_data_structures::fx::FxIndexMap;
-use rustc_data_structures::unord::UnordSet;
 use rustc_errors::ErrorGuaranteed;
-use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
 use rustc_index::bit_set::BitMatrix;
 use rustc_index::{Idx, IndexVec};
@@ -18,67 +16,6 @@ use std::fmt::{self, Debug};
 
 use super::{ConstValue, SourceInfo};
 
-#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)]
-pub enum UnsafetyViolationKind {
-    /// Unsafe operation outside `unsafe`.
-    General,
-    /// Unsafe operation in an `unsafe fn` but outside an `unsafe` block.
-    /// Has to be handled as a lint for backwards compatibility.
-    UnsafeFn,
-}
-
-#[derive(Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)]
-pub enum UnsafetyViolationDetails {
-    CallToUnsafeFunction,
-    UseOfInlineAssembly,
-    InitializingTypeWith,
-    CastOfPointerToInt,
-    UseOfMutableStatic,
-    UseOfExternStatic,
-    DerefOfRawPointer,
-    AccessToUnionField,
-    MutationOfLayoutConstrainedField,
-    BorrowOfLayoutConstrainedField,
-    CallToFunctionWith {
-        /// Target features enabled in callee's `#[target_feature]` but missing in
-        /// caller's `#[target_feature]`.
-        missing: Vec<Symbol>,
-        /// Target features in `missing` that are enabled at compile time
-        /// (e.g., with `-C target-feature`).
-        build_enabled: Vec<Symbol>,
-    },
-}
-
-#[derive(Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)]
-pub struct UnsafetyViolation {
-    pub source_info: SourceInfo,
-    pub lint_root: hir::HirId,
-    pub kind: UnsafetyViolationKind,
-    pub details: UnsafetyViolationDetails,
-}
-
-#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)]
-pub enum UnusedUnsafe {
-    /// `unsafe` block contains no unsafe operations
-    /// > ``unnecessary `unsafe` block``
-    Unused,
-    /// `unsafe` block nested under another (used) `unsafe` block
-    /// > ``… because it's nested under this `unsafe` block``
-    InUnsafeBlock(hir::HirId),
-}
-
-#[derive(TyEncodable, TyDecodable, HashStable, Debug)]
-pub struct UnsafetyCheckResult {
-    /// Violations that are propagated *upwards* from this function.
-    pub violations: Vec<UnsafetyViolation>,
-
-    /// Used `unsafe` blocks in this function. This is used for the "unused_unsafe" lint.
-    pub used_unsafe_blocks: UnordSet<hir::HirId>,
-
-    /// This is `Some` iff the item is not a closure.
-    pub unused_unsafes: Option<Vec<(hir::HirId, UnusedUnsafe)>>,
-}
-
 rustc_index::newtype_index! {
     #[derive(HashStable)]
     #[encodable]

compiler/rustc_middle/src/query/mod.rs

@@ -877,12 +877,6 @@ rustc_queries! {
         desc { |tcx| "collecting all inherent impls for `{:?}`", key }
     }
 
-    /// The result of unsafety-checking this `LocalDefId` with the old checker.
-    query mir_unsafety_check_result(key: LocalDefId) -> &'tcx mir::UnsafetyCheckResult {
-        desc { |tcx| "unsafety-checking `{}`", tcx.def_path_str(key) }
-        cache_on_disk_if { true }
-    }
-
     /// Unsafety-check this `LocalDefId`.
     query check_unsafety(key: LocalDefId) {
         desc { |tcx| "unsafety-checking `{}`", tcx.def_path_str(key) }

compiler/rustc_middle/src/ty/codec.rs

@@ -458,7 +458,6 @@ impl_decodable_via_ref! {
     &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
     &'tcx traits::ImplSource<'tcx, ()>,
     &'tcx mir::Body<'tcx>,
-    &'tcx mir::UnsafetyCheckResult,
     &'tcx mir::BorrowCheckResult<'tcx>,
     &'tcx mir::coverage::CodeRegion,
     &'tcx ty::List<ty::BoundVariableKind>,

compiler/rustc_mir_build/src/build/block.rs

@@ -13,31 +13,15 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         ast_block: BlockId,
         source_info: SourceInfo,
     ) -> BlockAnd<()> {
-        let Block { region_scope, span, ref stmts, expr, targeted_by_break, safety_mode } =
+        let Block { region_scope, span, ref stmts, expr, targeted_by_break, safety_mode: _ } =
             self.thir[ast_block];
         self.in_scope((region_scope, source_info), LintLevel::Inherited, move |this| {
             if targeted_by_break {
                 this.in_breakable_scope(None, destination, span, |this| {
-                    Some(this.ast_block_stmts(
-                        destination,
-                        block,
-                        span,
-                        stmts,
-                        expr,
-                        safety_mode,
-                        region_scope,
-                    ))
+                    Some(this.ast_block_stmts(destination, block, span, stmts, expr, region_scope))
                 })
             } else {
-                this.ast_block_stmts(
-                    destination,
-                    block,
-                    span,
-                    stmts,
-                    expr,
-                    safety_mode,
-                    region_scope,
-                )
+                this.ast_block_stmts(destination, block, span, stmts, expr, region_scope)
             }
         })
     }
@@ -49,7 +33,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         span: Span,
         stmts: &[StmtId],
         expr: Option<ExprId>,
-        safety_mode: BlockSafety,
         region_scope: Scope,
     ) -> BlockAnd<()> {
         let this = self;
@@ -72,13 +55,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         // First we build all the statements in the block.
         let mut let_scope_stack = Vec::with_capacity(8);
         let outer_source_scope = this.source_scope;
-        let outer_in_scope_unsafe = this.in_scope_unsafe;
         // This scope information is kept for breaking out of the parent remainder scope in case
         // one let-else pattern matching fails.
         // By doing so, we can be sure that even temporaries that receive extended lifetime
         // assignments are dropped, too.
         let mut last_remainder_scope = region_scope;
-        this.update_source_scope_for_safety_mode(span, safety_mode);
 
         let source_info = this.source_info(span);
         for stmt in stmts {
@@ -202,7 +183,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     let_scope_stack.push(remainder_scope);
 
                     let visibility_scope =
-                        Some(this.new_source_scope(remainder_span, LintLevel::Inherited, None));
+                        Some(this.new_source_scope(remainder_span, LintLevel::Inherited));
 
                     let initializer_span = this.thir[*initializer].span;
                     let scope = (*init_scope, source_info);
@@ -271,7 +252,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     let remainder_span = remainder_scope.span(this.tcx, this.region_scope_tree);
 
                     let visibility_scope =
-                        Some(this.new_source_scope(remainder_span, LintLevel::Inherited, None));
+                        Some(this.new_source_scope(remainder_span, LintLevel::Inherited));
 
                     // Evaluate the initializer, if present.
                     if let Some(init) = *initializer {
@@ -364,22 +345,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         }
         // Restore the original source scope.
         this.source_scope = outer_source_scope;
-        this.in_scope_unsafe = outer_in_scope_unsafe;
         block.unit()
     }
-
-    /// If we are entering an unsafe block, create a new source scope
-    fn update_source_scope_for_safety_mode(&mut self, span: Span, safety_mode: BlockSafety) {
-        debug!("update_source_scope_for({:?}, {:?})", span, safety_mode);
-        let new_unsafety = match safety_mode {
-            BlockSafety::Safe => return,
-            BlockSafety::BuiltinUnsafe => Safety::BuiltinUnsafe,
-            BlockSafety::ExplicitUnsafe(hir_id) => {
-                self.in_scope_unsafe = Safety::ExplicitUnsafe(hir_id);
-                Safety::ExplicitUnsafe(hir_id)
-            }
-        };
-
-        self.source_scope = self.new_source_scope(span, LintLevel::Inherited, Some(new_unsafety));
-    }
 }

compiler/rustc_mir_build/src/build/custom/mod.rs

@@ -72,10 +72,7 @@ pub(super) fn build_custom_mir<'tcx>(
         parent_scope: None,
         inlined: None,
         inlined_parent_scope: None,
-        local_data: ClearCrossCrate::Set(SourceScopeLocalData {
-            lint_root: hir_id,
-            safety: Safety::Safe,
-        }),
+        local_data: ClearCrossCrate::Set(SourceScopeLocalData { lint_root: hir_id }),
     });
     body.injection_phase = Some(parse_attribute(attr));
 

compiler/rustc_mir_build/src/build/expr/as_rvalue.rs

@@ -118,27 +118,20 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             ExprKind::Box { value } => {
                 let value_ty = this.thir[value].ty;
                 let tcx = this.tcx;
-
-                // `exchange_malloc` is unsafe but box is safe, so need a new scope.
-                let synth_scope = this.new_source_scope(
-                    expr_span,
-                    LintLevel::Inherited,
-                    Some(Safety::BuiltinUnsafe),
-                );
-                let synth_info = SourceInfo { span: expr_span, scope: synth_scope };
+                let source_info = this.source_info(expr_span);
 
                 let size = this.temp(tcx.types.usize, expr_span);
                 this.cfg.push_assign(
                     block,
-                    synth_info,
+                    source_info,
                     size,
                     Rvalue::NullaryOp(NullOp::SizeOf, value_ty),
                 );
 
                 let align = this.temp(tcx.types.usize, expr_span);
                 this.cfg.push_assign(
                     block,
-                    synth_info,
+                    source_info,
                     align,
                     Rvalue::NullaryOp(NullOp::AlignOf, value_ty),
                 );
@@ -154,7 +147,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 let success = this.cfg.start_new_block();
                 this.cfg.terminate(
                     block,
-                    synth_info,
+                    source_info,
                     TerminatorKind::Call {
                         func: exchange_malloc,
                         args: vec![