Remove "unnecessary unsafe block in unsafe fn" lint

Author: LeSeulArtichaut

src/librustc_mir/transform/check_unsafety.rs

@@ -548,14 +548,6 @@ fn is_enclosed(
     if parent_id != id {
         if used_unsafe.contains(&parent_id) {
             Some(("block".to_string(), parent_id))
-        } else if let Some(Node::Item(&hir::Item {
-            kind: hir::ItemKind::Fn(ref sig, _, _), ..
-        })) = tcx.hir().find(parent_id)
-        {
-            match sig.header.unsafety {
-                hir::Unsafety::Unsafe => Some(("fn".to_string(), parent_id)),
-                hir::Unsafety::Normal => None,
-            }
         } else {
             is_enclosed(tcx, used_unsafe, parent_id)
         }

src/librustc_mir_build/build/block.rs

@@ -210,7 +210,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             BlockSafety::ExplicitUnsafe(hir_id) => {
                 assert_eq!(self.push_unsafe_count, 0);
                 match self.unpushed_unsafe {
-                    Safety::Safe => {}
+                    Safety::Safe | Safety::FnUnsafe => {}
                     _ => return,
                 }
                 self.unpushed_unsafe = Safety::ExplicitUnsafe(hir_id);

src/test/ui/span/lint-unused-unsafe.rs

@@ -17,7 +17,7 @@ fn bad1() { unsafe {} }                  //~ ERROR: unnecessary `unsafe` block
 fn bad2() { unsafe { bad1() } }          //~ ERROR: unnecessary `unsafe` block
 unsafe fn bad3() { unsafe {} }           //~ ERROR: unnecessary `unsafe` block
 fn bad4() { unsafe { callback(||{}) } }  //~ ERROR: unnecessary `unsafe` block
-unsafe fn bad5() { unsafe { unsf() } }   //~ ERROR: unnecessary `unsafe` block
+unsafe fn bad5() { unsafe { unsf() } }
 fn bad6() {
     unsafe {                             // don't put the warning here
         unsafe {                         //~ ERROR: unnecessary `unsafe` block
@@ -26,7 +26,7 @@ fn bad6() {
     }
 }
 unsafe fn bad7() {
-    unsafe {                             //~ ERROR: unnecessary `unsafe` block
+    unsafe {
         unsafe {                         //~ ERROR: unnecessary `unsafe` block
             unsf()
         }

src/test/ui/span/lint-unused-unsafe.stderr

@@ -20,24 +20,14 @@ error: unnecessary `unsafe` block
   --> $DIR/lint-unused-unsafe.rs:18:20
    |
 LL | unsafe fn bad3() { unsafe {} }
-   | ----------------   ^^^^^^ unnecessary `unsafe` block
-   | |
-   | because it's nested under this `unsafe` fn
+   |                    ^^^^^^ unnecessary `unsafe` block
 
 error: unnecessary `unsafe` block
   --> $DIR/lint-unused-unsafe.rs:19:13
    |
 LL | fn bad4() { unsafe { callback(||{}) } }
    |             ^^^^^^ unnecessary `unsafe` block
 
-error: unnecessary `unsafe` block
-  --> $DIR/lint-unused-unsafe.rs:20:20
-   |
-LL | unsafe fn bad5() { unsafe { unsf() } }
-   | ----------------   ^^^^^^ unnecessary `unsafe` block
-   | |
-   | because it's nested under this `unsafe` fn
-
 error: unnecessary `unsafe` block
   --> $DIR/lint-unused-unsafe.rs:23:9
    |
@@ -46,22 +36,13 @@ LL |     unsafe {                             // don't put the warning here
 LL |         unsafe {
    |         ^^^^^^ unnecessary `unsafe` block
 
-error: unnecessary `unsafe` block
-  --> $DIR/lint-unused-unsafe.rs:29:5
-   |
-LL | unsafe fn bad7() {
-   | ---------------- because it's nested under this `unsafe` fn
-LL |     unsafe {
-   |     ^^^^^^ unnecessary `unsafe` block
-
 error: unnecessary `unsafe` block
   --> $DIR/lint-unused-unsafe.rs:30:9
    |
-LL | unsafe fn bad7() {
-   | ---------------- because it's nested under this `unsafe` fn
 LL |     unsafe {
+   |     ------ because it's nested under this `unsafe` block
 LL |         unsafe {
    |         ^^^^^^ unnecessary `unsafe` block
 
-error: aborting due to 8 previous errors
+error: aborting due to 6 previous errors