Make `i31ref` and `dataref` nullable (#4843)

Match the latest version of the GC spec. This change does not depend on V8
changing its interpretation of the shorthands because we are still temporarily
not emitting the binary shorthands, but all Binaryen users will have to update
their interpretations along with this change if they use the text or binary
shorthands.

5 files changed, 40 insertions, 58 deletions

diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index 81ae1bfc6..7385c18ea 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -85,56 +85,38 @@ static bool maybePrintRefShorthand(std::ostream& o, Type type) {
     return false;
   }
   auto heapType = type.getHeapType();
-  if (heapType.isBasic()) {
-    if (type.isNullable()) {
-      switch (heapType.getBasic()) {
-        case HeapType::ext:
-          o << "externref";
-          return true;
-        case HeapType::func:
-          o << "funcref";
-          return true;
-        case HeapType::any:
-          o << "anyref";
-          return true;
-        case HeapType::eq:
-          o << "eqref";
-          return true;
-        case HeapType::i31:
-        case HeapType::data:
-          break;
-        case HeapType::string:
-          o << "stringref";
-          return true;
-        case HeapType::stringview_wtf8:
-          o << "stringview_wtf8";
-          return true;
-        case HeapType::stringview_wtf16:
-          o << "stringview_wtf16";
-          return true;
-        case HeapType::stringview_iter:
-          o << "stringview_iter";
-          return true;
-      }
-    } else {
-      switch (heapType.getBasic()) {
-        case HeapType::ext:
-        case HeapType::func:
-        case HeapType::any:
-        case HeapType::eq:
-          break;
-        case HeapType::i31:
-          o << "i31ref";
-          return true;
-        case HeapType::data:
-          o << "dataref";
-          return true;
-        case HeapType::string:
-        case HeapType::stringview_wtf8:
-        case HeapType::stringview_wtf16:
-        case HeapType::stringview_iter:
-          break;
-      }
+  if (heapType.isBasic() && type.isNullable()) {
+    switch (heapType.getBasic()) {
+      case HeapType::ext:
+        o << "externref";
+        return true;
+      case HeapType::func:
+        o << "funcref";
+        return true;
+      case HeapType::any:
+        o << "anyref";
+        return true;
+      case HeapType::eq:
+        o << "eqref";
+        return true;
+      case HeapType::i31:
+        o << "i31ref";
+        return true;
+      case HeapType::data:
+        o << "dataref";
+        return true;
+      case HeapType::string:
+        o << "stringref";
+        return true;
+      case HeapType::stringview_wtf8:
+        o << "stringview_wtf8";
+        return true;
+      case HeapType::stringview_wtf16:
+        o << "stringview_wtf16";
+        return true;
+      case HeapType::stringview_iter:
+        o << "stringview_iter";
+        return true;
     }
   }
   return false;
diff --git a/src/wasm-type.h b/src/wasm-type.h
index 7235cda8b..778318794 100644
--- a/src/wasm-type.h
+++ b/src/wasm-type.h
@@ -143,8 +143,8 @@ public:
   // │ funcref     ║ x │   │ x │ x │ f  n  │ ┐ Ref
   // │ anyref      ║ x │   │ x │ x │ f? n  │ │  f_unc
   // │ eqref       ║ x │   │ x │ x │    n  │ │  n_ullable
-  // │ i31ref      ║ x │   │ x │ x │       │ │
-  // │ dataref     ║ x │   │ x │ x │       │ │
+  // │ i31ref      ║ x │   │ x │ x │    n  │ │
+  // │ dataref     ║ x │   │ x │ x │    n  │ │
   // ├─ Compound ──╫───┼───┼───┼───┤───────┤ │
   // │ Ref         ║   │ x │ x │ x │ f? n? │◄┘
   // │ Tuple       ║   │ x │   │ x │       │
diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 1fb43c884..685ad978d 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -1849,10 +1849,10 @@ bool WasmBinaryBuilder::getBasicType(int32_t code, Type& out) {
       out = Type(HeapType::eq, Nullable);
       return true;
     case BinaryConsts::EncodedType::i31ref:
-      out = Type(HeapType::i31, NonNullable);
+      out = Type(HeapType::i31, Nullable);
       return true;
     case BinaryConsts::EncodedType::dataref:
-      out = Type(HeapType::data, NonNullable);
+      out = Type(HeapType::data, Nullable);
       return true;
     case BinaryConsts::EncodedType::stringref:
       out = Type(HeapType::string, Nullable);
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 362ba25f9..a7d63a7c6 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -1179,10 +1179,10 @@ Type SExpressionWasmBuilder::stringToType(const char* str,
     return Type(HeapType::eq, Nullable);
   }
   if (strncmp(str, "i31ref", 6) == 0 && (prefix || str[6] == 0)) {
-    return Type(HeapType::i31, NonNullable);
+    return Type(HeapType::i31, Nullable);
   }
   if (strncmp(str, "dataref", 7) == 0 && (prefix || str[7] == 0)) {
-    return Type(HeapType::data, NonNullable);
+    return Type(HeapType::data, Nullable);
   }
   if (strncmp(str, "stringref", 9) == 0 && (prefix || str[9] == 0)) {
     return Type(HeapType::string, Nullable);
diff --git a/src/wasm/wat-parser.cpp b/src/wasm/wat-parser.cpp
index 843e26d08..9e843271f 100644
--- a/src/wasm/wat-parser.cpp
+++ b/src/wasm/wat-parser.cpp
@@ -1343,10 +1343,10 @@ MaybeResult<typename Ctx::TypeT> reftype(Ctx& ctx, ParseInput& in) {
     return ctx.makeRefType(ctx.makeEq(), Nullable);
   }
   if (in.takeKeyword("i31ref"sv)) {
-    return ctx.makeRefType(ctx.makeI31(), NonNullable);
+    return ctx.makeRefType(ctx.makeI31(), Nullable);
   }
   if (in.takeKeyword("dataref"sv)) {
-    return ctx.makeRefType(ctx.makeData(), NonNullable);
+    return ctx.makeRefType(ctx.makeData(), Nullable);
   }
   if (in.takeKeyword("arrayref"sv)) {
     return in.err("arrayref not yet supported");