16 pub struct VMExternRef(VMGcRef);  struct
18 impl fmt::Pointer for VMExternRef {  implementation
24 impl From<VMExternRef> for VMGcRef {
26     fn from(x: VMExternRef) -> Self {  in from()
35     pub fn into_externref(self, gc_heap: &impl GcHeap) -> Result<VMExternRef, VMGcRef> {  in into_externref()  argument
40             Ok(VMExternRef(self))  in into_externref()
54     pub fn into_externref_unchecked(self) -> VMExternRef {  in into_externref_unchecked()  argument
56         VMExternRef(self)  in into_externref_unchecked()
61     pub fn as_externref(&self, gc_heap: &(impl GcHeap + ?Sized)) -> Option<&VMExternRef> {  in as_externref()  argument
68             assert!(matches!(ret, VMExternRef(VMGcRef { .. })));  in as_externref()
76 impl VMExternRef {  impl