remove some unused code and types

Author: RalfJung

compiler/rustc_middle/src/mir/query.rs

@@ -2,7 +2,7 @@
 
 use crate::mir::{Body, ConstantKind, Promoted};
 use crate::ty::{self, OpaqueHiddenType, Ty, TyCtxt};
-use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::vec_map::VecMap;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
@@ -115,21 +115,6 @@ pub enum UnusedUnsafe {
     /// `unsafe` block nested under another (used) `unsafe` block
     /// > ``… because it's nested under this `unsafe` block``
     InUnsafeBlock(hir::HirId),
-    /// `unsafe` block nested under `unsafe fn`
-    /// > ``… because it's nested under this `unsafe fn` ``
-    ///
-    /// the second HirId here indicates the first usage of the `unsafe` block,
-    /// which allows retrieval of the LintLevelSource for why that operation would
-    /// have been permitted without the block
-    InUnsafeFn(hir::HirId, hir::HirId),
-}
-
-#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)]
-pub enum UsedUnsafeBlockData {
-    SomeDisallowedInUnsafeFn,
-    // the HirId here indicates the first usage of the `unsafe` block
-    // (i.e. the one that's first encountered in the MIR traversal of the unsafety check)
-    AllAllowedInUnsafeFn(hir::HirId),
 }
 
 #[derive(TyEncodable, TyDecodable, HashStable, Debug)]
@@ -138,10 +123,7 @@ pub struct UnsafetyCheckResult {
     pub violations: Vec<UnsafetyViolation>,
 
     /// Used `unsafe` blocks in this function. This is used for the "unused_unsafe" lint.
-    ///
-    /// The keys are the used `unsafe` blocks, the UnusedUnsafeKind indicates whether
-    /// or not any of the usages happen at a place that doesn't allow `unsafe_op_in_unsafe_fn`.
-    pub used_unsafe_blocks: FxHashMap<hir::HirId, UsedUnsafeBlockData>,
+    pub used_unsafe_blocks: FxHashSet<hir::HirId>,
 
     /// This is `Some` iff the item is not a closure.
     pub unused_unsafes: Option<Vec<(hir::HirId, UnusedUnsafe)>>,

compiler/rustc_mir_transform/src/check_unsafety.rs

@@ -1,4 +1,4 @@
-use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
@@ -11,7 +11,6 @@ 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::collections::hash_map;
 use std::ops::Bound;
 
 pub struct UnsafetyChecker<'a, 'tcx> {
@@ -26,7 +25,7 @@ pub struct UnsafetyChecker<'a, 'tcx> {
     ///
     /// The keys are the used `unsafe` blocks, the UnusedUnsafeKind indicates whether
     /// or not any of the usages happen at a place that doesn't allow `unsafe_op_in_unsafe_fn`.
-    used_unsafe_blocks: FxHashMap<HirId, UsedUnsafeBlockData>,
+    used_unsafe_blocks: FxHashSet<HirId>,
 }
 
 impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
@@ -130,10 +129,7 @@ impl<'tcx> Visitor<'tcx> for UnsafetyChecker<'_, 'tcx> {
                 &AggregateKind::Closure(def_id, _) | &AggregateKind::Generator(def_id, _, _) => {
                     let UnsafetyCheckResult { violations, used_unsafe_blocks, .. } =
                         self.tcx.unsafety_check_result(def_id);
-                    self.register_violations(
-                        violations,
-                        used_unsafe_blocks.iter().map(|(&h, &d)| (h, d)),
-                    );
+                    self.register_violations(violations, used_unsafe_blocks.iter().copied());
                 }
             },
             _ => {}
@@ -257,22 +253,8 @@ impl<'tcx> UnsafetyChecker<'_, 'tcx> {
     fn register_violations<'a>(
         &mut self,
         violations: impl IntoIterator<Item = &'a UnsafetyViolation>,
-        new_used_unsafe_blocks: impl IntoIterator<Item = (HirId, UsedUnsafeBlockData)>,
+        new_used_unsafe_blocks: impl IntoIterator<Item = HirId>,
     ) {
-        use UsedUnsafeBlockData::*;
-
-        let update_entry = |this: &mut Self, hir_id, new_usage| {
-            match this.used_unsafe_blocks.entry(hir_id) {
-                hash_map::Entry::Occupied(mut entry) => {
-                    if new_usage == SomeDisallowedInUnsafeFn {
-                        *entry.get_mut() = SomeDisallowedInUnsafeFn;
-                    }
-                }
-                hash_map::Entry::Vacant(entry) => {
-                    entry.insert(new_usage);
-                }
-            };
-        };
         let safety = self.body.source_scopes[self.source_info.scope]
             .local_data
             .as_ref()
@@ -300,17 +282,13 @@ impl<'tcx> UnsafetyChecker<'_, 'tcx> {
             }),
             Safety::BuiltinUnsafe => {}
             Safety::ExplicitUnsafe(hir_id) => violations.into_iter().for_each(|_violation| {
-                update_entry(
-                    self,
-                    hir_id,
-                    SomeDisallowedInUnsafeFn,
-                )
+                self.used_unsafe_blocks.insert(hir_id);
             }),
         };
 
-        new_used_unsafe_blocks
-            .into_iter()
-            .for_each(|(hir_id, usage_data)| update_entry(self, hir_id, usage_data));
+        new_used_unsafe_blocks.into_iter().for_each(|hir_id| {
+            self.used_unsafe_blocks.insert(hir_id);
+        });
     }
     fn check_mut_borrowing_layout_constrained_field(
         &mut self,
@@ -407,34 +385,28 @@ enum Context {
 
 struct UnusedUnsafeVisitor<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
-    used_unsafe_blocks: &'a FxHashMap<HirId, UsedUnsafeBlockData>,
+    used_unsafe_blocks: &'a FxHashSet<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>) {
-        use UsedUnsafeBlockData::{AllAllowedInUnsafeFn, SomeDisallowedInUnsafeFn};
-
         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, _) => Some(SomeDisallowedInUnsafeFn),
-                _ => self.used_unsafe_blocks.get(&block.hir_id).copied(),
+                (Level::Allow, _) => true,
+                _ => self.used_unsafe_blocks.contains(&block.hir_id),
             };
             let unused_unsafe = match (self.context, used) {
-                (_, None) => UnusedUnsafe::Unused,
-                (Context::Safe, Some(_))
-                | (Context::UnsafeFn(_), Some(SomeDisallowedInUnsafeFn)) => {
+                (_, 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::UnsafeFn(hir_id), Some(AllAllowedInUnsafeFn(lint_root))) => {
-                    UnusedUnsafe::InUnsafeFn(hir_id, lint_root)
-                }
-                (Context::UnsafeBlock(hir_id), Some(_)) => UnusedUnsafe::InUnsafeBlock(hir_id),
+                (Context::UnsafeBlock(hir_id), true) => UnusedUnsafe::InUnsafeBlock(hir_id),
             };
             self.unused_unsafes.push((block.hir_id, unused_unsafe));
         }
@@ -458,7 +430,7 @@ impl<'tcx> intravisit::Visitor<'tcx> for UnusedUnsafeVisitor<'_, 'tcx> {
 fn check_unused_unsafe(
     tcx: TyCtxt<'_>,
     def_id: LocalDefId,
-    used_unsafe_blocks: &FxHashMap<HirId, UsedUnsafeBlockData>,
+    used_unsafe_blocks: &FxHashSet<HirId>,
 ) -> Vec<(HirId, UnusedUnsafe)> {
     let body_id = tcx.hir().maybe_body_owned_by(def_id);
 
@@ -518,11 +490,6 @@ fn unsafety_check_result<'tcx>(
 }
 
 fn report_unused_unsafe(tcx: TyCtxt<'_>, kind: UnusedUnsafe, id: HirId) {
-    if matches!(kind, UnusedUnsafe::InUnsafeFn(..)) {
-        // We do *not* warn here, these unsafe blocks are actually required when
-        // `unsafe_op_in_unsafe_fn` is warn or higher.
-        return;
-    }
     let span = tcx.sess.source_map().guess_head_span(tcx.hir().span(id));
     tcx.struct_span_lint_hir(UNUSED_UNSAFE, id, span, |lint| {
         let msg = "unnecessary `unsafe` block";
@@ -536,7 +503,6 @@ fn report_unused_unsafe(tcx: TyCtxt<'_>, kind: UnusedUnsafe, id: HirId) {
                     "because it's nested under this `unsafe` block",
                 );
             }
-            UnusedUnsafe::InUnsafeFn(_id, _usage_lint_root) => unreachable!(),
         }
 
         db.emit();