Formatting changes + add UI test

compiler/rustc_mir_transform/src/check_unsafety.rs

@@ -1,10 +1,10 @@
-use hir::{BlockCheckMode, ExprKind, Node};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 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::ty::query::Providers;
@@ -521,10 +521,7 @@ pub fn check_unsafety(tcx: TyCtxt<'_>, def_id: LocalDefId) {
         match kind {
             UnsafetyViolationKind::General => {
                 // once
-                // Mutable statics always require an unsafe block
-                let unsafe_fn_msg = if unsafe_op_in_unsafe_fn_allowed(tcx, lint_root)
-                    && details != UnsafetyViolationDetails::UseOfMutableStatic
-                {
+                let unsafe_fn_msg = if unsafe_op_in_unsafe_fn_allowed(tcx, lint_root) {
                     " function or"
                 } else {
                     ""
@@ -542,12 +539,14 @@ pub fn check_unsafety(tcx: TyCtxt<'_>, def_id: LocalDefId) {
                 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
-                        }
+                        && let BlockCheckMode::UnsafeBlock(_) = block.rules
+                    {
+                        true
+                    }
                     else if let Some(sig) = tcx.hir().fn_sig_by_hir_id(*id)
-                        && sig.header.is_unsafe() {
-                            true
+                        && sig.header.is_unsafe()
+                    {
+                        true
                     } else {
                         false
                     }

src/test/ui/unsafe/unsafe-not-inherited.rs

@@ -0,0 +1,26 @@
+#![allow(unused, dead_code)]
+
+static mut FOO: u64 = 0;
+
+fn static_mod() {
+    unsafe {static BAR: u64 = FOO;}
+    //~^ ERROR: use of mutable static is unsafe
+    //~| NOTE: use of mutable static
+    //~| NOTE: mutable statics can be mutated by multiple threads
+    //~| NOTE: items do not inherit unsafety
+}
+
+unsafe fn unsafe_call() {}
+fn foo() {
+    unsafe {
+    //~^ NOTE: items do not inherit unsafety
+        fn bar() {
+            unsafe_call();
+            //~^ ERROR: call to unsafe function
+            //~| NOTE: call to unsafe function
+            //~| NOTE: consult the function's documentation
+        }
+    }
+}
+
+fn main() {}

src/test/ui/unsafe/unsafe-not-inherited.stderr

@@ -0,0 +1,24 @@
+error[E0133]: use of mutable static is unsafe and requires unsafe function or block
+  --> $DIR/unsafe-not-inherited.rs:6:31
+   |
+LL |     unsafe {static BAR: u64 = FOO;}
+   |     ------                    ^^^ use of mutable static
+   |     |
+   |     items do not inherit unsafety from separate enclosing items
+   |
+   = note: mutable statics can be mutated by multiple threads: aliasing violations or data races will cause undefined behavior
+
+error[E0133]: call to unsafe function is unsafe and requires unsafe function or block
+  --> $DIR/unsafe-not-inherited.rs:18:13
+   |
+LL |     unsafe {
+   |     ------ items do not inherit unsafety from separate enclosing items
+...
+LL |             unsafe_call();
+   |             ^^^^^^^^^^^^^ call to unsafe function
+   |
+   = note: consult the function's documentation for information on how to avoid undefined behavior
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0133`.