4 files changed, 14 insertions, 4 deletions
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index e65f4beab24..41b43f64798 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -948,7 +948,7 @@ declare_lint! {
     ///
     /// ### Example
     ///
-    /// ```rust,compile_fail
+    /// ```rust,compile_fail,edition2021
     /// #[no_mangle]
     /// const FOO: i32 = 5;
     /// ```
diff --git a/compiler/rustc_lint/src/impl_trait_overcaptures.rs b/compiler/rustc_lint/src/impl_trait_overcaptures.rs
index f1dc420aa3c..7f4789ad0d9 100644
--- a/compiler/rustc_lint/src/impl_trait_overcaptures.rs
+++ b/compiler/rustc_lint/src/impl_trait_overcaptures.rs
@@ -41,7 +41,7 @@ declare_lint! {
     ///
     /// ### Example
     ///
-    /// ```rust,compile_fail
+    /// ```rust,compile_fail,edition2021
     /// # #![deny(impl_trait_overcaptures)]
     /// # use std::fmt::Display;
     /// let mut x = vec![];
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index daddd45d597..96705e79e0a 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -21,6 +21,7 @@
 
 // tidy-alphabetical-start
 #![allow(internal_features)]
+#![cfg_attr(bootstrap, feature(let_chains))]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(array_windows)]
@@ -28,7 +29,6 @@
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
 #![feature(iter_order_by)]
-#![feature(let_chains)]
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
 #![feature(try_blocks)]
diff --git a/compiler/rustc_lint/src/types.rs b/compiler/rustc_lint/src/types.rs
index a084dacfb5b..f9dce5a5198 100644
--- a/compiler/rustc_lint/src/types.rs
+++ b/compiler/rustc_lint/src/types.rs
@@ -1,7 +1,9 @@
 use std::iter;
 use std::ops::ControlFlow;
 
-use rustc_abi::{BackendRepr, TagEncoding, VariantIdx, Variants, WrappingRange};
+use rustc_abi::{
+    BackendRepr, Integer, IntegerType, TagEncoding, VariantIdx, Variants, WrappingRange,
+};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::DiagMessage;
 use rustc_hir::intravisit::VisitorExt;
@@ -1243,6 +1245,14 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                             };
                         }
 
+                        if let Some(IntegerType::Fixed(Integer::I128, _)) = def.repr().int {
+                            return FfiUnsafe {
+                                ty,
+                                reason: fluent::lint_improper_ctypes_128bit,
+                                help: None,
+                            };
+                        }
+
                         use improper_ctypes::check_non_exhaustive_variant;
 
                         let non_exhaustive = def.variant_list_has_applicable_non_exhaustive();