chore: Add Debug for ExternalReference (denoland#1272)

src/external_references.rs

@@ -11,6 +11,7 @@ use crate::NamedGetterCallback;
 use crate::NamedSetterCallback;
 use crate::PropertyEnumeratorCallback;
 use std::ffi::c_void;
+use std::fmt::Debug;
 
 #[derive(Clone, Copy)]
 pub union ExternalReference<'s> {
@@ -26,6 +27,13 @@ pub union ExternalReference<'s> {
  pub pointer: *mut c_void,
 }
 
+impl<'s> Debug for ExternalReference<'s> {
+ fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+ // SAFETY: All union fields are the same size
+ unsafe { (self.pointer).fmt(f) }
+ }
+}
+
 #[derive(Debug, Clone)]
 pub struct ExternalReferences {
  null_terminated: Vec<intptr_t>,

tests/test_api.rs

@@ -5309,7 +5309,7 @@ fn external_references() {
  let external_ptr = Box::into_raw(vec![0_u8, 1, 2, 3, 4].into_boxed_slice())
  as *mut [u8] as *mut c_void;
  // Push them to the external reference table.
- let refs = v8::ExternalReferences::new(&[
+ let refs = [
  v8::ExternalReference {
  function: fn_callback.map_fn_to(),
  },
@@ -5319,7 +5319,10 @@ fn external_references() {
  v8::ExternalReference {
  pointer: external_ptr,
  },
- ]);
+ ];
+ // Exercise the Debug impl
+ println!("{refs:?}");
+ let refs = v8::ExternalReferences::new(&refs);
  // TODO(piscisaureus): leaking the `ExternalReferences` collection shouldn't
  // be necessary. The reference needs to remain valid for the lifetime of the
  // `SnapshotCreator` or `Isolate` that uses it, which would be the case here