Add IS_MANUALLY_DROP to AdtFlags

Author: matthewjasper

src/librustc/ty/mod.rs

@@ -1792,19 +1792,22 @@ bitflags! {
         const IS_STRUCT           = 1 << 2;
         /// Indicates whether the ADT is a struct and has a constructor.
         const HAS_CTOR            = 1 << 3;
-        /// Indicates whether the type is a `PhantomData`.
+        /// Indicates whether the type is `PhantomData`.
         const IS_PHANTOM_DATA     = 1 << 4;
         /// Indicates whether the type has a `#[fundamental]` attribute.
         const IS_FUNDAMENTAL      = 1 << 5;
-        /// Indicates whether the type is a `Box`.
+        /// Indicates whether the type is `Box`.
         const IS_BOX              = 1 << 6;
+        /// Indicates whether the type is `ManuallyDrop`.
+        const IS_MANUALLY_DROP    = 1 << 7;
+        // FIXME(matthewjasper) replace these with diagnostic items
         /// Indicates whether the type is an `Arc`.
-        const IS_ARC              = 1 << 7;
+        const IS_ARC              = 1 << 8;
         /// Indicates whether the type is an `Rc`.
-        const IS_RC               = 1 << 8;
+        const IS_RC               = 1 << 9;
         /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
         /// (i.e., this flag is never set unless this ADT is an enum).
-        const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 9;
+        const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 10;
     }
 }
 
@@ -2180,6 +2183,9 @@ impl<'tcx> AdtDef {
         if Some(did) == tcx.lang_items().owned_box() {
             flags |= AdtFlags::IS_BOX;
         }
+        if Some(did) == tcx.lang_items().manually_drop() {
+            flags |= AdtFlags::IS_MANUALLY_DROP;
+        }
         if Some(did) == tcx.lang_items().arc() {
             flags |= AdtFlags::IS_ARC;
         }
@@ -2280,6 +2286,12 @@ impl<'tcx> AdtDef {
         self.flags.contains(AdtFlags::IS_BOX)
     }
 
+    /// Returns `true` if this is ManuallyDrop<T>.
+    #[inline]
+    pub fn is_manually_drop(&self) -> bool {
+        self.flags.contains(AdtFlags::IS_MANUALLY_DROP)
+    }
+
     /// Returns `true` if this type has a destructor.
     pub fn has_dtor(&self, tcx: TyCtxt<'tcx>) -> bool {
         self.destructor(tcx).is_some()