Extend unused_must_use to cover block exprs

Author: jieyouxu

core/src/primitive_docs.rs

@@ -308,7 +308,7 @@ mod prim_never {}
 ///
 /// ```no_run
 /// // Undefined behaviour
-/// unsafe { char::from_u32_unchecked(0x110000) };
+/// let _ = unsafe { char::from_u32_unchecked(0x110000) };
 /// ```
 ///
 /// USVs are also the exact set of values that may be encoded in UTF-8. Because

core/tests/ptr.rs

@@ -1001,7 +1001,7 @@ fn nonnull_tagged_pointer_with_provenance() {
     assert_eq!(p.tag(), 3);
     assert_eq!(unsafe { *p.pointer().as_ptr() }, 10);
 
-    unsafe { Box::from_raw(p.pointer().as_ptr()) };
+    unsafe { drop(Box::from_raw(p.pointer().as_ptr())) };
 
     /// A non-null pointer type which carries several bits of metadata and maintains provenance.
     #[repr(transparent)]

std/src/primitive_docs.rs

@@ -308,7 +308,7 @@ mod prim_never {}
 ///
 /// ```no_run
 /// // Undefined behaviour
-/// unsafe { char::from_u32_unchecked(0x110000) };
+/// let _ = unsafe { char::from_u32_unchecked(0x110000) };
 /// ```
 ///
 /// USVs are also the exact set of values that may be encoded in UTF-8. Because