3 files changed, 3 insertions, 0 deletions
diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index 6421504b896..5f207295683 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -228,6 +228,7 @@ mod thin;
 #[lang = "owned_box"]
 #[fundamental]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_insignificant_dtor]
 // The declaration of the `Box` struct must be kept in sync with the
 // compiler or ICEs will happen.
 pub struct Box<
diff --git a/library/alloc/src/ffi/c_str.rs b/library/alloc/src/ffi/c_str.rs
index 797d591a8b5..d496899e72b 100644
--- a/library/alloc/src/ffi/c_str.rs
+++ b/library/alloc/src/ffi/c_str.rs
@@ -696,6 +696,7 @@ impl CString {
 // memory-unsafe code from working by accident. Inline
 // to prevent LLVM from optimizing it away in debug builds.
 #[stable(feature = "cstring_drop", since = "1.13.0")]
+#[rustc_insignificant_dtor]
 impl Drop for CString {
     #[inline]
     fn drop(&mut self) {
diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs
index ced789c4f92..5d099a49854 100644
--- a/library/alloc/src/sync.rs
+++ b/library/alloc/src/sync.rs
@@ -237,6 +237,7 @@ macro_rules! acquire {
 /// [rc_examples]: crate::rc#examples
 #[cfg_attr(not(test), rustc_diagnostic_item = "Arc")]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_insignificant_dtor]
 pub struct Arc<
     T: ?Sized,
     #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,