2 files changed, 8 insertions, 0 deletions
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 79c8046f9b7..2d596564d52 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -326,6 +326,12 @@ impl EarlyLintPass for UnsafeCode {
                 self.report_unsafe(cx, it.span, BuiltinUnsafe::GlobalAsm);
             }
 
+            ast::ItemKind::ForeignMod(ForeignMod { safety, .. }) => {
+                if let Safety::Unsafe(_) = safety {
+                    self.report_unsafe(cx, it.span, BuiltinUnsafe::UnsafeExternBlock);
+                }
+            }
+
             _ => {}
         }
     }
diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
index 7c5640f5959..eacc66b197a 100644
--- a/compiler/rustc_lint/src/lints.rs
+++ b/compiler/rustc_lint/src/lints.rs
@@ -81,6 +81,8 @@ pub enum BuiltinUnsafe {
     AllowInternalUnsafe,
     #[diag(lint_builtin_unsafe_block)]
     UnsafeBlock,
+    #[diag(lint_builtin_unsafe_extern_block)]
+    UnsafeExternBlock,
     #[diag(lint_builtin_unsafe_trait)]
     UnsafeTrait,
     #[diag(lint_builtin_unsafe_impl)]