diff --git a/library/core/src/mem/mod.rs b/library/core/src/mem/mod.rs
index 1671c8219de16..c951a4d1829a6 100644
--- a/library/core/src/mem/mod.rs
+++ b/library/core/src/mem/mod.rs
@@ -705,9 +705,24 @@ pub const unsafe fn zeroed<T>() -> T {
 /// Therefore, it is immediate undefined behavior to call this function on nearly all types,
 /// including integer types and arrays of integer types, and even if the result is unused.
 ///
+/// # Safety
+///
+/// This function is highly unsafe, as calling this function on nearly all types causes
+/// undefined behavior. You should **always** prefer using [`MaybeUninit<T>`] instead.
+///
+/// If you absolutely must use this function, the following conditions must be upheld:
+///
+/// - `T` must be *valid* with any sequence of bytes of the appropriate length,
+///   initialized or uninitialized.
+/// - `T` must be *[inhabited]*, i.e. possible to construct. This means that types
+///   like zero-variant enums and [`!`] are unsound to construct with this function.
+/// - You must use the value only in ways which do not violate any *safety*
+///   invariants of the type.
+///
 /// [uninit]: MaybeUninit::uninit
 /// [assume_init]: MaybeUninit::assume_init
 /// [inv]: MaybeUninit#initialization-invariant
+/// [inhabited]: https://doc.rust-lang.org/reference/glossary.html#inhabited
 #[inline(always)]
 #[must_use]
 #[deprecated(since = "1.39.0", note = "use `mem::MaybeUninit` instead")]
diff --git a/tests/ui/thir-print/offset_of.stdout b/tests/ui/thir-print/offset_of.stdout
index b3791a2446cb4..c6fe88da57514 100644
--- a/tests/ui/thir-print/offset_of.stdout
+++ b/tests/ui/thir-print/offset_of.stdout
@@ -67,8 +67,8 @@ body:
                                                 }
                                             )
                                             else_block: None
-                                            hir_id: HirId(DefId(offset_of::concrete).10)
-                                            span: $DIR/offset_of.rs:37:5: 1440:57 (#0)
+                                            lint_level: Explicit(HirId(DefId(offset_of::concrete).10))
+                                            span: $DIR/offset_of.rs:37:5: 1455:57 (#0)
                                         }
                                     }
                                     Stmt {
@@ -116,8 +116,8 @@ body:
                                                 }
                                             )
                                             else_block: None
-                                            hir_id: HirId(DefId(offset_of::concrete).20)
-                                            span: $DIR/offset_of.rs:38:5: 1440:57 (#0)
+                                            lint_level: Explicit(HirId(DefId(offset_of::concrete).20))
+                                            span: $DIR/offset_of.rs:38:5: 1455:57 (#0)
                                         }
                                     }
                                     Stmt {
@@ -165,8 +165,8 @@ body:
                                                 }
                                             )
                                             else_block: None
-                                            hir_id: HirId(DefId(offset_of::concrete).30)
-                                            span: $DIR/offset_of.rs:39:5: 1440:57 (#0)
+                                            lint_level: Explicit(HirId(DefId(offset_of::concrete).30))
+                                            span: $DIR/offset_of.rs:39:5: 1455:57 (#0)
                                         }
                                     }
                                     Stmt {
@@ -214,8 +214,8 @@ body:
                                                 }
                                             )
                                             else_block: None
-                                            hir_id: HirId(DefId(offset_of::concrete).40)
-                                            span: $DIR/offset_of.rs:40:5: 1440:57 (#0)
+                                            lint_level: Explicit(HirId(DefId(offset_of::concrete).40))
+                                            span: $DIR/offset_of.rs:40:5: 1455:57 (#0)
                                         }
                                     }
                                     Stmt {
@@ -263,8 +263,8 @@ body:
                                                 }
                                             )
                                             else_block: None
-                                            hir_id: HirId(DefId(offset_of::concrete).50)
-                                            span: $DIR/offset_of.rs:41:5: 1440:57 (#0)
+                                            lint_level: Explicit(HirId(DefId(offset_of::concrete).50))
+                                            span: $DIR/offset_of.rs:41:5: 1455:57 (#0)
                                         }
                                     }
                                 ]
@@ -863,8 +863,8 @@ body:
                                                 }
                                             )
                                             else_block: None
-                                            hir_id: HirId(DefId(offset_of::generic).12)
-                                            span: $DIR/offset_of.rs:45:5: 1440:57 (#0)
+                                            lint_level: Explicit(HirId(DefId(offset_of::generic).12))
+                                            span: $DIR/offset_of.rs:45:5: 1455:57 (#0)
                                         }
                                     }
                                     Stmt {
@@ -912,8 +912,8 @@ body:
                                                 }
                                             )
                                             else_block: None
-                                            hir_id: HirId(DefId(offset_of::generic).24)
-                                            span: $DIR/offset_of.rs:46:5: 1440:57 (#0)
+                                            lint_level: Explicit(HirId(DefId(offset_of::generic).24))
+                                            span: $DIR/offset_of.rs:46:5: 1455:57 (#0)
                                         }
                                     }
                                     Stmt {
@@ -961,8 +961,8 @@ body:
                                                 }
                                             )
                                             else_block: None
-                                            hir_id: HirId(DefId(offset_of::generic).36)
-                                            span: $DIR/offset_of.rs:47:5: 1440:57 (#0)
+                                            lint_level: Explicit(HirId(DefId(offset_of::generic).36))
+                                            span: $DIR/offset_of.rs:47:5: 1455:57 (#0)
                                         }
                                     }
                                     Stmt {
@@ -1010,8 +1010,8 @@ body:
                                                 }
                                             )
                                             else_block: None
-                                            hir_id: HirId(DefId(offset_of::generic).48)
-                                            span: $DIR/offset_of.rs:48:5: 1440:57 (#0)
+                                            lint_level: Explicit(HirId(DefId(offset_of::generic).48))
+                                            span: $DIR/offset_of.rs:48:5: 1455:57 (#0)
                                         }
                                     }
                                 ]