Rollup merge of #22542 - ipetkov:unsafe-lint, r=huonw

This allows warning or forbidding all uses of unsafe code, whereas
previously only unsafe blocks were caught by the lint.

The lint has been renamed from `unsafe-blocks` to `unsafe-code` to
reflect its new purpose.

This is a minor [breaking-change]

Closes #22430

src/test/compile-fail/lint-unsafe-block.rs

@@ -1,28 +0,0 @@
-// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-#![allow(unused_unsafe)]
-#![allow(dead_code)]
-#![deny(unsafe_blocks)]
-unsafe fn allowed() {}
-
-#[allow(unsafe_blocks)] fn also_allowed() { unsafe {} }
-
-macro_rules! unsafe_in_macro {
-    () => {
-        unsafe {} //~ ERROR: usage of an `unsafe` block
-    }
-}
-
-fn main() {
-    unsafe {} //~ ERROR: usage of an `unsafe` block
-
-    unsafe_in_macro!()
-}

src/test/compile-fail/lint-unsafe-code.rs

@@ -0,0 +1,50 @@
+// Copyright 2013-2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![allow(unused_unsafe)]
+#![allow(dead_code)]
+#![deny(unsafe_code)]
+
+struct Bar;
+
+#[allow(unsafe_code)]
+mod allowed_unsafe {
+    fn allowed() { unsafe {} }
+    unsafe fn also_allowed() {}
+    unsafe trait AllowedUnsafe {}
+    unsafe impl AllowedUnsafe for super::Bar {}
+}
+
+macro_rules! unsafe_in_macro {
+    () => {
+        unsafe {} //~ ERROR: usage of an `unsafe` block
+    }
+}
+
+unsafe fn baz() {} //~ ERROR: declaration of an `unsafe` function
+unsafe trait Foo {} //~ ERROR: declaration of an `unsafe` trait
+unsafe impl Foo for Bar {} //~ ERROR: implementation of an `unsafe` trait
+
+trait Baz {
+    unsafe fn baz(&self); //~ ERROR: declaration of an `unsafe` method
+    unsafe fn provided(&self) {} //~ ERROR: implementation of an `unsafe` method
+    unsafe fn provided_override(&self) {} //~ ERROR: implementation of an `unsafe` method
+}
+
+impl Baz for Bar {
+    unsafe fn baz(&self) {} //~ ERROR: implementation of an `unsafe` method
+    unsafe fn provided_override(&self) {} //~ ERROR: implementation of an `unsafe` method
+}
+
+fn main() {
+    unsafe {} //~ ERROR: usage of an `unsafe` block
+
+    unsafe_in_macro!()
+}