Remove some last remants of {push,pop}_unsafe!

compiler/rustc_hir/src/hir.rs

@@ -1205,8 +1205,6 @@ pub struct ExprField<'hir> {
 pub enum BlockCheckMode {
     DefaultBlock,
     UnsafeBlock(UnsafeSource),
-    PushUnsafeBlock(UnsafeSource),
-    PopUnsafeBlock(UnsafeSource),
 }
 
 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]

compiler/rustc_hir_pretty/src/lib.rs

@@ -1070,8 +1070,6 @@ impl<'a> State<'a> {
     ) {
         match blk.rules {
             hir::BlockCheckMode::UnsafeBlock(..) => self.word_space("unsafe"),
-            hir::BlockCheckMode::PushUnsafeBlock(..) => self.word_space("push_unsafe"),
-            hir::BlockCheckMode::PopUnsafeBlock(..) => self.word_space("pop_unsafe"),
             hir::BlockCheckMode::DefaultBlock => (),
         }
         self.maybe_print_comment(blk.span.lo());

compiler/rustc_middle/src/mir/mod.rs

@@ -494,8 +494,6 @@ impl<'tcx> Body<'tcx> {
 #[derive(Copy, Clone, PartialEq, Eq, Debug, TyEncodable, TyDecodable, HashStable)]
 pub enum Safety {
     Safe,
-    /// Unsafe because of a PushUnsafeBlock
-    BuiltinUnsafe,
     /// Unsafe because of an unsafe fn
     FnUnsafe,
     /// Unsafe because of an `unsafe` block

compiler/rustc_middle/src/thir.rs

@@ -101,8 +101,6 @@ pub struct Block {
 pub enum BlockSafety {
     Safe,
     ExplicitUnsafe(hir::HirId),
-    PushUnsafe,
-    PopUnsafe,
 }
 
 #[derive(Debug, HashStable)]

compiler/rustc_mir/src/transform/check_unsafety.rs

@@ -321,7 +321,6 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
                 }
                 false
             }
-            Safety::BuiltinUnsafe => true,
             Safety::ExplicitUnsafe(hir_id) => {
                 // mark unsafe block as used if there are any unsafe operations inside
                 if !violations.is_empty() {

compiler/rustc_mir_build/src/build/block.rs

@@ -74,8 +74,7 @@ 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_push_unsafe_count = this.push_unsafe_count;
-        let outer_unpushed_unsafe = this.unpushed_unsafe;
+        let outer_in_scope_unsafe = this.in_scope_unsafe;
         this.update_source_scope_for_safety_mode(span, safety_mode);
 
         let source_info = this.source_info(span);
@@ -206,8 +205,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         }
         // Restore the original source scope.
         this.source_scope = outer_source_scope;
-        this.push_unsafe_count = outer_push_unsafe_count;
-        this.unpushed_unsafe = outer_unpushed_unsafe;
+        this.in_scope_unsafe = outer_in_scope_unsafe;
         block.unit()
     }
 
@@ -217,29 +215,17 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         let new_unsafety = match safety_mode {
             BlockSafety::Safe => None,
             BlockSafety::ExplicitUnsafe(hir_id) => {
-                assert_eq!(self.push_unsafe_count, 0);
-                match self.unpushed_unsafe {
+                match self.in_scope_unsafe {
                     Safety::Safe => {}
                     // no longer treat `unsafe fn`s as `unsafe` contexts (see RFC #2585)
                     Safety::FnUnsafe
                         if self.tcx.lint_level_at_node(UNSAFE_OP_IN_UNSAFE_FN, hir_id).0
                             != Level::Allow => {}
                     _ => return,
                 }
-                self.unpushed_unsafe = Safety::ExplicitUnsafe(hir_id);
+                self.in_scope_unsafe = Safety::ExplicitUnsafe(hir_id);
                 Some(Safety::ExplicitUnsafe(hir_id))
             }
-            BlockSafety::PushUnsafe => {
-                self.push_unsafe_count += 1;
-                Some(Safety::BuiltinUnsafe)
-            }
-            BlockSafety::PopUnsafe => {
-                self.push_unsafe_count = self
-                    .push_unsafe_count
-                    .checked_sub(1)
-                    .unwrap_or_else(|| span_bug!(span, "unsafe count underflow"));
-                if self.push_unsafe_count == 0 { Some(self.unpushed_unsafe) } else { None }
-            }
         };
 
         if let Some(unsafety) = new_unsafety {

compiler/rustc_mir_build/src/build/mod.rs

@@ -367,12 +367,8 @@ struct Builder<'a, 'tcx> {
     /// `{ STMTS; EXPR1 } + EXPR2`.
     block_context: BlockContext,
 
-    /// The current unsafe block in scope, even if it is hidden by
-    /// a `PushUnsafeBlock`.
-    unpushed_unsafe: Safety,
-
-    /// The number of `push_unsafe_block` levels in scope.
-    push_unsafe_count: usize,
+    /// The current unsafe block in scope
+    in_scope_unsafe: Safety,
 
     /// The vector of all scopes that we have created thus far;
     /// we track this for debuginfo later.
@@ -877,8 +873,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             source_scopes: IndexVec::new(),
             source_scope: OUTERMOST_SOURCE_SCOPE,
             guard_context: vec![],
-            push_unsafe_count: 0,
-            unpushed_unsafe: safety,
+            in_scope_unsafe: safety,
             local_decls: IndexVec::from_elem_n(LocalDecl::new(return_ty, return_span), 1),
             canonical_user_type_annotations: IndexVec::new(),
             upvar_mutbls: vec![],

compiler/rustc_mir_build/src/thir/cx/block.rs

@@ -27,8 +27,6 @@ impl<'tcx> Cx<'tcx> {
             safety_mode: match block.rules {
                 hir::BlockCheckMode::DefaultBlock => BlockSafety::Safe,
                 hir::BlockCheckMode::UnsafeBlock(..) => BlockSafety::ExplicitUnsafe(block.hir_id),
-                hir::BlockCheckMode::PushUnsafeBlock(..) => BlockSafety::PushUnsafe,
-                hir::BlockCheckMode::PopUnsafeBlock(..) => BlockSafety::PopUnsafe,
             },
         }
     }

compiler/rustc_typeck/src/check/mod.rs

@@ -174,13 +174,12 @@ impl Needs {
 pub struct UnsafetyState {
     pub def: hir::HirId,
     pub unsafety: hir::Unsafety,
-    pub unsafe_push_count: u32,
     from_fn: bool,
 }
 
 impl UnsafetyState {
     pub fn function(unsafety: hir::Unsafety, def: hir::HirId) -> UnsafetyState {
-        UnsafetyState { def, unsafety, unsafe_push_count: 0, from_fn: true }
+        UnsafetyState { def, unsafety, from_fn: true }
     }
 
     pub fn recurse(self, blk: &hir::Block<'_>) -> UnsafetyState {
@@ -193,19 +192,11 @@ impl UnsafetyState {
             hir::Unsafety::Unsafe if self.from_fn => self,
 
             unsafety => {
-                let (unsafety, def, count) = match blk.rules {
-                    BlockCheckMode::PushUnsafeBlock(..) => {
-                        (unsafety, blk.hir_id, self.unsafe_push_count.checked_add(1).unwrap())
-                    }
-                    BlockCheckMode::PopUnsafeBlock(..) => {
-                        (unsafety, blk.hir_id, self.unsafe_push_count.checked_sub(1).unwrap())
-                    }
-                    BlockCheckMode::UnsafeBlock(..) => {
-                        (hir::Unsafety::Unsafe, blk.hir_id, self.unsafe_push_count)
-                    }
-                    BlockCheckMode::DefaultBlock => (unsafety, self.def, self.unsafe_push_count),
+                let (unsafety, def) = match blk.rules {
+                    BlockCheckMode::UnsafeBlock(..) => (hir::Unsafety::Unsafe, blk.hir_id),
+                    BlockCheckMode::DefaultBlock => (unsafety, self.def),
                 };
-                UnsafetyState { def, unsafety, unsafe_push_count: count, from_fn: false }
+                UnsafetyState { def, unsafety, from_fn: false }
             }
         }
     }

src/tools/clippy/clippy_lints/src/derive.rs

@@ -411,9 +411,7 @@ impl<'tcx> Visitor<'tcx> for UnsafeVisitor<'_, 'tcx> {
 
         if let ExprKind::Block(block, _) = expr.kind {
             match block.rules {
-                BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided)
-                | BlockCheckMode::PushUnsafeBlock(UnsafeSource::UserProvided)
-                | BlockCheckMode::PopUnsafeBlock(UnsafeSource::UserProvided) => {
+                BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided) => {
                     self.has_unsafe = true;
                 },
                 _ => {},