[C API] Align I31ref and Dataref to be nullable (#5153)

The C API still returned non nullable types for `dataref` (`ref data` instead of `ref null data`) and `i31ref` (`ref i31` instead of `ref null i31`). This PR aligns with the current state of the GC proposal, making them nullable when obtained via the C API.

4 files changed, 9 insertions, 8 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d79c1c0f8..876a96032 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -25,6 +25,7 @@ Current Trunk
 - Implemented bottom heap types: `none`, `nofunc`, and `noextern`. RefNull
   expressions and null `Literal`s must now have type `nullref`, `nullfuncref`,
   or `nullexternref`.
+* The C-API's `BinaryenTypeI31ref` and `BinaryenTypeDataref` now return nullable types.
 
 v110
 ----
diff --git a/src/binaryen-c.cpp b/src/binaryen-c.cpp
index cd3806810..4501a67e0 100644
--- a/src/binaryen-c.cpp
+++ b/src/binaryen-c.cpp
@@ -197,10 +197,10 @@ BinaryenType BinaryenTypeEqref(void) {
   return Type(HeapType::eq, Nullable).getID();
 }
 BinaryenType BinaryenTypeI31ref(void) {
-  return Type(HeapType::i31, NonNullable).getID();
+  return Type(HeapType::i31, Nullable).getID();
 }
 BinaryenType BinaryenTypeDataref(void) {
-  return Type(HeapType::data, NonNullable).getID();
+  return Type(HeapType::data, Nullable).getID();
 }
 BinaryenType BinaryenTypeArrayref(void) {
   return Type(HeapType::array, Nullable).getID();
diff --git a/test/binaryen.js/expressions.js b/test/binaryen.js/expressions.js
index 71846f3c6..c0bc402a0 100644
--- a/test/binaryen.js/expressions.js
+++ b/test/binaryen.js/expressions.js
@@ -1814,13 +1814,13 @@ console.log("# I31New");
   assert(theI31New instanceof binaryen.I31New);
   assert(theI31New instanceof binaryen.Expression);
   assert(theI31New.value === value);
-  assert(theI31New.type === binaryen.i31ref);
+  // assert(theI31New.type === binaryen.?); // TODO: (ref i31)
 
   theI31New.value = value = module.local.get(2, binaryen.i32);
   assert(theI31New.value === value);
   theI31New.type = binaryen.f64;
   theI31New.finalize();
-  assert(theI31New.type === binaryen.i31ref);
+  // assert(theI31New.type === binaryen.?); // TODO: (ref i31)
 
   console.log(theI31New.toText());
   assert(
diff --git a/test/binaryen.js/kitchen-sink.js.txt b/test/binaryen.js/kitchen-sink.js.txt
index 104405c8a..89c49f2d5 100644
--- a/test/binaryen.js/kitchen-sink.js.txt
+++ b/test/binaryen.js/kitchen-sink.js.txt
@@ -2176,10 +2176,10 @@ getExpressionInfo(tuple[3])={"id":14,"type":5,"value":3.7}
        (pop eqref)
       )
       (drop
-       (pop (ref i31))
+       (pop i31ref)
       )
       (drop
-       (pop (ref data))
+       (pop dataref)
       )
       (drop
        (pop stringref)
@@ -4280,10 +4280,10 @@ getExpressionInfo(tuple[3])={"id":14,"type":5,"value":3.7}
        (pop eqref)
       )
       (drop
-       (pop (ref i31))
+       (pop i31ref)
       )
       (drop
-       (pop (ref data))
+       (pop dataref)
       )
       (drop
        (pop stringref)