Auto merge of #68494 - matthewjasper:internal-static-ptrs, r=nikomatsakis

Make pointers to statics internal

Closes #67611

r? @nikomatsakis

Author: bors

src/librustc_mir/transform/check_unsafety.rs

@@ -233,28 +233,30 @@ impl<'a, 'tcx> Visitor<'tcx> for UnsafetyChecker<'a, 'tcx> {
             if let (local, []) = (&place.local, proj_base) {
                 let decl = &self.body.local_decls[*local];
                 if decl.internal {
-                    // Internal locals are used in the `move_val_init` desugaring.
-                    // We want to check unsafety against the source info of the
-                    // desugaring, rather than the source info of the RHS.
-                    self.source_info = self.body.local_decls[*local].source_info;
-                } else if let LocalInfo::StaticRef { def_id, .. } = decl.local_info {
-                    if self.tcx.is_mutable_static(def_id) {
-                        self.require_unsafe(
-                            "use of mutable static",
-                            "mutable statics can be mutated by multiple threads: aliasing \
-                        violations or data races will cause undefined behavior",
-                            UnsafetyViolationKind::General,
-                        );
-                        return;
-                    } else if self.tcx.is_foreign_item(def_id) {
-                        self.require_unsafe(
-                            "use of extern static",
-                            "extern statics are not controlled by the Rust type system: \
-                        invalid data, aliasing violations or data races will cause \
-                        undefined behavior",
-                            UnsafetyViolationKind::General,
-                        );
-                        return;
+                    if let LocalInfo::StaticRef { def_id, .. } = decl.local_info {
+                        if self.tcx.is_mutable_static(def_id) {
+                            self.require_unsafe(
+                                "use of mutable static",
+                                "mutable statics can be mutated by multiple threads: aliasing \
+                            violations or data races will cause undefined behavior",
+                                UnsafetyViolationKind::General,
+                            );
+                            return;
+                        } else if self.tcx.is_foreign_item(def_id) {
+                            self.require_unsafe(
+                                "use of extern static",
+                                "extern statics are not controlled by the Rust type system: \
+                            invalid data, aliasing violations or data races will cause \
+                            undefined behavior",
+                                UnsafetyViolationKind::General,
+                            );
+                            return;
+                        }
+                    } else {
+                        // Internal locals are used in the `move_val_init` desugaring.
+                        // We want to check unsafety against the source info of the
+                        // desugaring, rather than the source info of the RHS.
+                        self.source_info = self.body.local_decls[*local].source_info;
                     }
                 }
             }

src/librustc_mir_build/build/expr/as_temp.rs

@@ -61,6 +61,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             }
             if let ExprKind::StaticRef { def_id, .. } = expr.kind {
                 let is_thread_local = this.hir.tcx().has_attr(def_id, sym::thread_local);
+                local_decl.internal = true;
                 local_decl.local_info = LocalInfo::StaticRef { def_id, is_thread_local };
             }
             this.local_decls.push(local_decl)

src/librustc_typeck/check/generator_interior.rs

@@ -222,8 +222,6 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
     }
 
     fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
-        let scope = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
-
         match &expr.kind {
             ExprKind::Call(callee, args) => match &callee.kind {
                 ExprKind::Path(qpath) => {
@@ -249,20 +247,13 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
                 }
                 _ => intravisit::walk_expr(self, expr),
             },
-            ExprKind::Path(qpath) => {
-                let res = self.fcx.tables.borrow().qpath_res(qpath, expr.hir_id);
-                if let Res::Def(DefKind::Static, def_id) = res {
-                    // Statics are lowered to temporary references or
-                    // pointers in MIR, so record that type.
-                    let ptr_ty = self.fcx.tcx.static_ptr_ty(def_id);
-                    self.record(ptr_ty, scope, Some(expr), expr.span);
-                }
-            }
             _ => intravisit::walk_expr(self, expr),
         }
 
         self.expr_count += 1;
 
+        let scope = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
+
         // If there are adjustments, then record the final type --
         // this is the actual value that is being produced.
         if let Some(adjusted_ty) = self.fcx.tables.borrow().expr_ty_adjusted_opt(expr) {

src/test/ui/async-await/issues/issue-67611-static-mut-refs.rs

@@ -0,0 +1,33 @@
+// build-pass
+// edition:2018
+
+static mut A: [i32; 5] = [1, 2, 3, 4, 5];
+
+fn is_send_sync<T: Send + Sync>(_: T) {}
+
+async fn fun() {
+    let u = unsafe { A[async { 1 }.await] };
+    unsafe {
+        match A {
+            i if async { true }.await => (),
+            _ => (),
+        }
+    }
+}
+
+fn main() {
+    let index_block = async {
+        let u = unsafe { A[async { 1 }.await] };
+    };
+    let match_block = async {
+        unsafe {
+            match A {
+                i if async { true }.await => (),
+                _ => (),
+            }
+        }
+    };
+    is_send_sync(index_block);
+    is_send_sync(match_block);
+    is_send_sync(fun());
+}

src/test/ui/generator/static-mut-reference-across-yield.rs

@@ -0,0 +1,29 @@
+// build-pass
+#![feature(generators)]
+
+static mut A: [i32; 5] = [1, 2, 3, 4, 5];
+
+fn is_send_sync<T: Send + Sync>(_: T) {}
+
+fn main() {
+    unsafe {
+        let gen_index = static || {
+            let u = A[{
+                yield;
+                1
+            }];
+        };
+        let gen_match = static || match A {
+            i if {
+                yield;
+                true
+            } =>
+            {
+                ()
+            }
+            _ => (),
+        };
+        is_send_sync(gen_index);
+        is_send_sync(gen_match);
+    }
+}