diff --git a/test/js-api/gc/casts.tentative.any.js b/test/js-api/gc/casts.tentative.any.js
new file mode 100644
index 000000000..13ade4efa
--- /dev/null
+++ b/test/js-api/gc/casts.tentative.any.js
@@ -0,0 +1,200 @@
+// META: global=window,dedicatedworker,jsshell
+// META: script=/wasm/jsapi/wasm-module-builder.js
+
+let exports = {};
+setup(() => {
+  const builder = new WasmModuleBuilder();
+  const structIndex = builder.addStruct([makeField(kWasmI32, true)]);
+  const arrayIndex = builder.addArray(kWasmI32, true);
+  const structIndex2 = builder.addStruct([makeField(kWasmF32, true)]);
+  const arrayIndex2 = builder.addArray(kWasmF32, true);
+  const funcIndex = builder.addType({ params: [], results: [] });
+
+  const anyRef = wasmRefType(kWasmAnyRef);
+  const eqRef = wasmRefType(kWasmEqRef);
+  const structRef = wasmRefType(kWasmStructRef);
+  const arrayRef = wasmRefType(kWasmArrayRef);
+  const i31Ref = wasmRefType(kWasmI31Ref);
+  const funcRef = wasmRefType(kWasmFuncRef);
+
+  builder
+    .addFunction("anyArg", makeSig_v_x(anyRef))
+    .addBody([])
+    .exportFunc();
+
+  builder
+    .addFunction("eqArg", makeSig_v_x(eqRef))
+    .addBody([])
+    .exportFunc();
+
+  builder
+    .addFunction("structArg", makeSig_v_x(structRef))
+    .addBody([])
+    .exportFunc();
+
+  builder
+    .addFunction("arrayArg", makeSig_v_x(arrayRef))
+    .addBody([])
+    .exportFunc();
+
+  builder
+    .addFunction("i31Arg", makeSig_v_x(i31Ref))
+    .addBody([])
+    .exportFunc();
+
+  builder
+    .addFunction("funcArg", makeSig_v_x(funcRef))
+    .addBody([])
+    .exportFunc();
+
+  builder
+    .addFunction("concreteStructArg", makeSig_v_x(wasmRefType(structIndex)))
+    .addBody([])
+    .exportFunc();
+
+  builder
+    .addFunction("concreteArrayArg", makeSig_v_x(wasmRefType(arrayIndex)))
+    .addBody([])
+    .exportFunc();
+
+  builder
+    .addFunction("concreteFuncArg", makeSig_v_x(wasmRefType(funcIndex)))
+    .addBody([])
+    .exportFunc();
+
+  builder
+    .addFunction("makeStruct", makeSig_r_v(wasmRefType(structIndex)))
+    .addBody([...wasmI32Const(42),
+              ...GCInstr(kExprStructNew), structIndex])
+    .exportFunc();
+
+  builder
+    .addFunction("makeArray", makeSig_r_v(wasmRefType(arrayIndex)))
+    .addBody([...wasmI32Const(5), ...wasmI32Const(42),
+              ...GCInstr(kExprArrayNew), arrayIndex])
+    .exportFunc();
+
+  builder
+    .addFunction("makeStruct2", makeSig_r_v(wasmRefType(structIndex2)))
+    .addBody([...wasmF32Const(42),
+              ...GCInstr(kExprStructNew), structIndex2])
+    .exportFunc();
+
+  builder
+    .addFunction("makeArray2", makeSig_r_v(wasmRefType(arrayIndex2)))
+    .addBody([...wasmF32Const(42), ...wasmI32Const(5),
+              ...GCInstr(kExprArrayNew), arrayIndex2])
+    .exportFunc();
+
+  builder
+    .addFunction("testFunc", funcIndex)
+    .addBody([])
+    .exportFunc();
+
+  const buffer = builder.toBuffer();
+  const module = new WebAssembly.Module(buffer);
+  const instance = new WebAssembly.Instance(module, {});
+  exports = instance.exports;
+});
+
+test(() => {
+  exports.anyArg(exports.makeStruct());
+  exports.anyArg(exports.makeArray());
+  exports.anyArg(42);
+  exports.anyArg(42n);
+  exports.anyArg("foo");
+  exports.anyArg({});
+  exports.anyArg(() => {});
+  assert_throws_js(TypeError, () => exports.anyArg(exports.testFunc));
+}, "anyref casts");
+
+test(() => {
+  exports.eqArg(exports.makeStruct());
+  exports.eqArg(exports.makeArray());
+  exports.eqArg(42);
+  assert_throws_js(TypeError, () => exports.eqArg(42n));
+  assert_throws_js(TypeError, () => exports.eqArg("foo"));
+  assert_throws_js(TypeError, () => exports.eqArg({}));
+  assert_throws_js(TypeError, () => exports.eqArg(exports.testFunc));
+  assert_throws_js(TypeError, () => exports.eqArg(() => {}));
+}, "eqref casts");
+
+test(() => {
+  exports.structArg(exports.makeStruct());
+  assert_throws_js(TypeError, () => exports.structArg(exports.makeArray()));
+  assert_throws_js(TypeError, () => exports.structArg(42));
+  assert_throws_js(TypeError, () => exports.structArg(42n));
+  assert_throws_js(TypeError, () => exports.structArg("foo"));
+  assert_throws_js(TypeError, () => exports.structArg({}));
+  assert_throws_js(TypeError, () => exports.structArg(exports.testFunc));
+  assert_throws_js(TypeError, () => exports.structArg(() => {}));
+}, "structref casts");
+
+test(() => {
+  exports.arrayArg(exports.makeArray());
+  assert_throws_js(TypeError, () => exports.arrayArg(exports.makeStruct()));
+  assert_throws_js(TypeError, () => exports.arrayArg(42));
+  assert_throws_js(TypeError, () => exports.arrayArg(42n));
+  assert_throws_js(TypeError, () => exports.arrayArg("foo"));
+  assert_throws_js(TypeError, () => exports.arrayArg({}));
+  assert_throws_js(TypeError, () => exports.arrayArg(exports.testFunc));
+  assert_throws_js(TypeError, () => exports.arrayArg(() => {}));
+}, "arrayref casts");
+
+test(() => {
+  exports.i31Arg(42);
+  assert_throws_js(TypeError, () => exports.i31Arg(exports.makeStruct()));
+  assert_throws_js(TypeError, () => exports.i31Arg(exports.makeArray()));
+  assert_throws_js(TypeError, () => exports.i31Arg(42n));
+  assert_throws_js(TypeError, () => exports.i31Arg("foo"));
+  assert_throws_js(TypeError, () => exports.i31Arg({}));
+  assert_throws_js(TypeError, () => exports.i31Arg(exports.testFunc));
+  assert_throws_js(TypeError, () => exports.i31Arg(() => {}));
+}, "i31ref casts");
+
+test(() => {
+  exports.funcArg(exports.testFunc);
+  assert_throws_js(TypeError, () => exports.funcArg(exports.makeStruct()));
+  assert_throws_js(TypeError, () => exports.funcArg(exports.makeArray()));
+  assert_throws_js(TypeError, () => exports.funcArg(42));
+  assert_throws_js(TypeError, () => exports.funcArg(42n));
+  assert_throws_js(TypeError, () => exports.funcArg("foo"));
+  assert_throws_js(TypeError, () => exports.funcArg({}));
+  assert_throws_js(TypeError, () => exports.funcArg(() => {}));
+}, "funcref casts");
+
+test(() => {
+  exports.concreteStructArg(exports.makeStruct());
+  assert_throws_js(TypeError, () => exports.concreteStructArg(exports.makeStruct2()));
+  assert_throws_js(TypeError, () => exports.concreteStructArg(exports.makeArray()));
+  assert_throws_js(TypeError, () => exports.concreteStructArg(42));
+  assert_throws_js(TypeError, () => exports.concreteStructArg(42n));
+  assert_throws_js(TypeError, () => exports.concreteStructArg("foo"));
+  assert_throws_js(TypeError, () => exports.concreteStructArg({}));
+  assert_throws_js(TypeError, () => exports.concreteStructArg(exports.testFunc));
+  assert_throws_js(TypeError, () => exports.concreteStructArg(() => {}));
+}, "concrete struct casts");
+
+test(() => {
+  exports.concreteArrayArg(exports.makeArray());
+  assert_throws_js(TypeError, () => exports.concreteArrayArg(exports.makeArray2()));
+  assert_throws_js(TypeError, () => exports.concreteArrayArg(exports.makeStruct()));
+  assert_throws_js(TypeError, () => exports.concreteArrayArg(42));
+  assert_throws_js(TypeError, () => exports.concreteArrayArg(42n));
+  assert_throws_js(TypeError, () => exports.concreteArrayArg("foo"));
+  assert_throws_js(TypeError, () => exports.concreteArrayArg({}));
+  assert_throws_js(TypeError, () => exports.concreteArrayArg(exports.testFunc));
+  assert_throws_js(TypeError, () => exports.concreteArrayArg(() => {}));
+}, "concrete array casts");
+
+test(() => {
+  exports.concreteFuncArg(exports.testFunc);
+  assert_throws_js(TypeError, () => exports.concreteFuncArg(exports.makeArray()));
+  assert_throws_js(TypeError, () => exports.concreteFuncArg(exports.makeStruct()));
+  assert_throws_js(TypeError, () => exports.concreteFuncArg(42));
+  assert_throws_js(TypeError, () => exports.concreteFuncArg(42n));
+  assert_throws_js(TypeError, () => exports.concreteFuncArg("foo"));
+  assert_throws_js(TypeError, () => exports.concreteFuncArg({}));
+  assert_throws_js(TypeError, () => exports.concreteFuncArg(exports.eqArg));
+  assert_throws_js(TypeError, () => exports.concreteFuncArg(() => {}));
+}, "concrete func casts");