Add binary format parse checking for ref.as input type (#4389)

If that type is not valid then we cannot even create and finalize the node,
which means we'd hit an assertion inside finalize(), before we reach the
validator.

Fixes #4383

1 files changed, 3 insertions, 0 deletions

diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index bf29f948b..d8a3c2f74 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -6898,6 +6898,9 @@ void WasmBinaryBuilder::visitRefAs(RefAs* curr, uint8_t code) {
       WASM_UNREACHABLE("invalid code for ref.as_*");
   }
   curr->value = popNonVoidExpression();
+  if (!curr->value->type.isRef() && curr->value->type != Type::unreachable) {
+    throwError("bad input type for ref.as: " + curr->value->type.toString());
+  }
   curr->finalize();
 }