diagnostics: tweak error message to give more rationale to unsafe Fn

Author: notriddle

core/src/ops/function.rs

@@ -61,8 +61,9 @@
     ),
     on(
         _Self = "unsafe fn",
+        note = "unsafe function cannot be called generically without an unsafe block",
         // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
-        note = "unsafe functions must be wrapped in closures: `|| unsafe {{ /* code */ }}`"
+        label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
     ),
     message = "expected a `{Fn}<{Args}>` closure, found `{Self}`",
     label = "expected an `Fn<{Args}>` closure, found `{Self}`"
@@ -146,8 +147,9 @@ pub trait Fn<Args>: FnMut<Args> {
     ),
     on(
         _Self = "unsafe fn",
+        note = "unsafe function cannot be called generically without an unsafe block",
         // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
-        note = "unsafe functions must be wrapped in closures: `|| unsafe {{ /* code */ }}`"
+        label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
     ),
     message = "expected a `{FnMut}<{Args}>` closure, found `{Self}`",
     label = "expected an `FnMut<{Args}>` closure, found `{Self}`"
@@ -223,8 +225,9 @@ pub trait FnMut<Args>: FnOnce<Args> {
     ),
     on(
         _Self = "unsafe fn",
+        note = "unsafe function cannot be called generically without an unsafe block",
         // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
-        note = "unsafe functions must be wrapped in closures: `|| unsafe {{ /* code */ }}`"
+        label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
     ),
     message = "expected a `{FnOnce}<{Args}>` closure, found `{Self}`",
     label = "expected an `FnOnce<{Args}>` closure, found `{Self}`"