Auto merge of #112038 - Nemo157:edition-2024-unsafe_op_in_unsafe_fn, r=RalfJung

Change `unsafe_op_in_unsafe_fn` to be `warn`-by-default from edition 2024

This was previously FCPed: https://github.com/rust-lang/rust/issues/71668#issuecomment-1189396886

There were two blocking requirements:
* Fix the `unused_unsafe` lint, done in https://github.com/rust-lang/rust/pull/100081
* Have `cargo fix` able to fix the lint, done in https://github.com/rust-lang/rust/pull/112017

compiler/rustc_lint_defs/src/builtin.rs

@@ -2554,8 +2554,8 @@
     ///
     /// The fix to this is to wrap the unsafe code in an `unsafe` block.
     ///
-    /// This lint is "allow" by default since this will affect a large amount
-    /// of existing code, and the exact plan for increasing the severity is
+    /// This lint is "allow" by default on editions up to 2021, from 2024 it is
+    /// "warn" by default; the plan for increasing severity further is
     /// still being considered. See [RFC #2585] and [issue #71668] for more
     /// details.
     ///
@@ -2567,6 +2567,7 @@
     pub UNSAFE_OP_IN_UNSAFE_FN,
     Allow,
     "unsafe operations in unsafe functions without an explicit unsafe block are deprecated",
+    @edition Edition2024 => Warn;
 }
 
 declare_lint! {

compiler/rustc_lint_defs/src/lib.rs

@@ -719,36 +719,24 @@ macro_rules! declare_lint {
     ($(#[$attr:meta])* $vis: vis $NAME: ident, $Level: ident, $desc: expr,
      $(@feature_gate = $gate:expr;)?
      $(@future_incompatible = FutureIncompatibleInfo { $($field:ident : $val:expr),* $(,)*  }; )?
+     $(@edition $lint_edition:ident => $edition_level:ident;)?
      $($v:ident),*) => (
         $(#[$attr])*
         $vis static $NAME: &$crate::Lint = &$crate::Lint {
             name: stringify!($NAME),
             default_level: $crate::$Level,
             desc: $desc,
-            edition_lint_opts: None,
             is_plugin: false,
             $($v: true,)*
-            $(feature_gate: Some($gate),)*
+            $(feature_gate: Some($gate),)?
             $(future_incompatible: Some($crate::FutureIncompatibleInfo {
                 $($field: $val,)*
                 ..$crate::FutureIncompatibleInfo::default_fields_for_macro()
-            }),)*
+            }),)?
+            $(edition_lint_opts: Some(($crate::Edition::$lint_edition, $crate::$edition_level)),)?
             ..$crate::Lint::default_fields_for_macro()
         };
     );
-    ($(#[$attr:meta])* $vis: vis $NAME: ident, $Level: ident, $desc: expr,
-     $lint_edition: expr => $edition_level: ident
-    ) => (
-        $(#[$attr])*
-        $vis static $NAME: &$crate::Lint = &$crate::Lint {
-            name: stringify!($NAME),
-            default_level: $crate::$Level,
-            desc: $desc,
-            edition_lint_opts: Some(($lint_edition, $crate::Level::$edition_level)),
-            report_in_external_macro: false,
-            is_plugin: false,
-        };
-    );
 }
 
 #[macro_export]

tests/ui/unsafe/edition-2024-unsafe_op_in_unsafe_fn.rs

@@ -0,0 +1,17 @@
+// edition: 2024
+// compile-flags: -Zunstable-options
+// check-pass
+
+#![crate_type = "lib"]
+
+#![deny(unused_unsafe)]
+
+unsafe fn unsf() {}
+
+unsafe fn foo() {
+    unsf();
+    //~^ WARN call to unsafe function is unsafe and requires unsafe block
+
+    // no unused_unsafe
+    unsafe { unsf(); }
+}

tests/ui/unsafe/edition-2024-unsafe_op_in_unsafe_fn.stderr

@@ -0,0 +1,16 @@
+warning: call to unsafe function is unsafe and requires unsafe block (error E0133)
+  --> $DIR/edition-2024-unsafe_op_in_unsafe_fn.rs:12:5
+   |
+LL |     unsf();
+   |     ^^^^^^ call to unsafe function
+   |
+   = note: consult the function's documentation for information on how to avoid undefined behavior
+note: an unsafe function restricts its caller, but its body is safe by default
+  --> $DIR/edition-2024-unsafe_op_in_unsafe_fn.rs:11:1
+   |
+LL | unsafe fn foo() {
+   | ^^^^^^^^^^^^^^^
+   = note: `#[warn(unsafe_op_in_unsafe_fn)]` on by default
+
+warning: 1 warning emitted
+