Add is_dangling

Author: lucic71

libcc2rs/src/fn_ptr.rs

@@ -158,6 +158,9 @@ impl<T: 'static> ErasedPtr for FnPtr<T> {
     fn is_null(&self) -> bool {
         FnPtr::is_null(self)
     }
+    fn is_dangling(&self) -> bool {
+        false
+    }
 }
 
 impl<T: 'static> FnPtr<T> {

libcc2rs/src/rc.rs

@@ -1091,6 +1091,7 @@ pub(crate) trait ErasedPtr: std::any::Any {
     fn as_any(&self) -> &dyn std::any::Any;
     fn equals(&self, other: &dyn ErasedPtr) -> bool;
     fn is_null(&self) -> bool;
+    fn is_dangling(&self) -> bool;
 }
 
 impl PartialEq for dyn ErasedPtr {
@@ -1122,6 +1123,16 @@ where
     fn is_null(&self) -> bool {
         Ptr::is_null(self)
     }
+
+    fn is_dangling(&self) -> bool {
+        match &self.kind {
+            PtrKind::Null => false,
+            PtrKind::StackSingle(w) | PtrKind::HeapSingle(w) => w.strong_count() == 0,
+            PtrKind::Vec(w) => w.strong_count() == 0,
+            PtrKind::StackArray(w) | PtrKind::HeapArray(w) => w.strong_count() == 0,
+            PtrKind::Reinterpreted(data) => data.alloc.is_dangling(),
+        }
+    }
 }
 
 #[derive(Clone)]

libcc2rs/src/reinterpret.rs

@@ -104,6 +104,7 @@ pub trait OriginalAlloc {
     // Stable address used for pointer equality across PtrKind variants.
     fn address(&self) -> usize;
     fn delete(&self);
+    fn is_dangling(&self) -> bool;
 }
 
 // Read bytes starting at `byte_offset` from a slice of S elements into `buf`.
@@ -178,6 +179,10 @@ impl<T: ByteRepr> OriginalAlloc for SingleOriginalAlloc<T> {
         }
         assert_eq!(Weak::strong_count(&self.weak), 0, "ub: double free");
     }
+
+    fn is_dangling(&self) -> bool {
+        self.weak.strong_count() == 0
+    }
 }
 
 pub(crate) trait AsSlice {
@@ -241,4 +246,8 @@ impl<T: AsSlice + 'static> OriginalAlloc for SliceOriginalAlloc<T> {
         }
         assert_eq!(Weak::strong_count(&self.weak), 0, "ub: double free");
     }
+
+    fn is_dangling(&self) -> bool {
+        self.weak.strong_count() == 0
+    }
 }