PR fixup

1 files changed, 16 insertions, 7 deletions

diff --git a/compiler/rustc_ty_utils/src/needs_drop.rs b/compiler/rustc_ty_utils/src/needs_drop.rs
index 039cbaf4982..98415a84c56 100644
--- a/compiler/rustc_ty_utils/src/needs_drop.rs
+++ b/compiler/rustc_ty_utils/src/needs_drop.rs
@@ -240,13 +240,22 @@ fn adt_significant_drop_tys(
     def_id: DefId,
 ) -> Result<&ty::List<Ty<'_>>, AlwaysRequiresDrop> {
     let adt_has_dtor = |adt_def: &ty::AdtDef| {
-        adt_def.destructor(tcx).map(|dtor| {
-            if tcx.has_attr(dtor.did, sym::rustc_insignificant_dtor) {
-                DtorType::Insignificant
-            } else {
-                DtorType::Significant
-            }
-        })
+        let is_marked_insig = tcx.has_attr(adt_def.did, sym::rustc_insignificant_dtor);
+        if is_marked_insig {
+            // In some cases like `std::collections::HashMap` where the struct is a wrapper around
+            // a type that is a Drop type, and the wrapped type (eg: `hashbrown::HashMap`) lies
+            // outside stdlib, we might choose to still annotate the the wrapper (std HashMap) with
+            // `rustc_insignificant_dtor`, even if the type itself doesn't have a `Drop` impl.
+            Some(DtorType::Insignificant)
+        } else if adt_def.destructor(tcx).is_some() {
+            // There is a Drop impl and the type isn't marked insignificant, therefore Drop must be
+            // significant.
+            Some(DtorType::Significant)
+        } else {
+            // No destructor found nor the type is annotated with `rustc_insignificant_dtor`, we
+            // treat this as the simple case of Drop impl for type.
+            None
+        }
     };
     adt_drop_tys_helper(tcx, def_id, adt_has_dtor)
 }