No longer walk (inline) constants with UnusedUnsafeVisitor

Author: steffahn

compiler/rustc_mir_transform/src/check_unsafety.rs

@@ -439,6 +439,8 @@ impl<'tcx> intravisit::Visitor<'tcx> for UnusedUnsafeVisitor<'_, 'tcx> {
         }
         intravisit::walk_block(self, block);
     }
+
+    fn visit_anon_const(&mut self, _c: &'tcx hir::AnonConst) {}
 }
 
 fn check_unused_unsafe(

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

@@ -1140,5 +1140,17 @@ LL |     async unsafe fn async_blocks() {
 LL |                 let _ = async { unsafe { let _ = async { unsf() }; }};
    |                                 ^^^^^^ unnecessary `unsafe` block
 
-error: aborting due to 140 previous errors
+error: unnecessary `unsafe` block
+  --> $DIR/lint-unused-unsafe.rs:754:22
+   |
+LL |         let _x: [(); unsafe { 0 }] = [];
+   |                      ^^^^^^ unnecessary `unsafe` block
+
+error: unnecessary `unsafe` block
+  --> $DIR/lint-unused-unsafe.rs:758:22
+   |
+LL |         let _x: [(); unsafe { unsafe { size() } }] = [];
+   |                      ^^^^^^ unnecessary `unsafe` block
+
+error: aborting due to 142 previous errors
 

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

@@ -745,4 +745,18 @@ mod additional_tests_extra {
             }};
         }
     }
+
+    fn used_unsafe_in_const() {
+        let _x: [(); unsafe { size() }] = [];
+    }
+
+    fn unused_unsafe_in_const_1() {
+        let _x: [(); unsafe { 0 }] = []; //~ ERROR: unnecessary `unsafe` block
+    }
+
+    fn unused_unsafe_in_const_2() {
+        let _x: [(); unsafe { unsafe { size() } }] = []; //~ ERROR: unnecessary `unsafe` block
+    }
+
+    const unsafe fn size() -> usize { 0 } 
 }