From b4f29078e3757eb818277de192b653c1e459bc89 Mon Sep 17 00:00:00 2001
From: Sam Estep <sam@samestep.com>
Date: Thu, 15 Feb 2024 12:52:21 -0500
Subject: [PATCH] Update Node status for tail calls (#370)

Using [Binaryen
v116](https://github.com/WebAssembly/binaryen/tree/version_116),
assemble `fac.wat` (adapted from
[here](https://github.com/WebAssembly/tail-call/blob/6f44ca27af411a0f6bc4e07520807d7adfc0de88/proposals/tail-call/Overview.md#examples))

```wat
(module
  (func (export "fac") (param $x i64) (result i64)
    (return_call $fac-aux (local.get $x) (i64.const 1)))
  (func $fac-aux (param $x i64) (param $r i64) (result i64)
    (if (i64.eqz (local.get $x))
      (then (return (local.get $r)))
      (else
        (return_call $fac-aux
          (i64.sub (local.get $x) (i64.const 1))
          (i64.mul (local.get $x) (local.get $r)))))))
```

via this command:

```sh
wasm-as --enable-tail-call fac.wat
```

Then try to run `fac.mjs`

```js
import * as fs from "fs/promises";

const bytes = await fs.readFile("fac.wasm");
const mod = await WebAssembly.compile(bytes);
const { fac } = (await WebAssembly.instantiate(mod)).exports;
console.log(fac(5n));
```

via this command:

```sh
node fac.mjs
```

Node v20.0.0 or newer prints `120n` as expected, while Node v19.9.0
instead gives this error message:

```
node:internal/process/esm_loader:100
    internalBinding('errors').triggerUncaughtException(
                              ^

[CompileError: WebAssembly.compile(): Compiling function #0 failed: Invalid opcode 0x12 (enable with --experimental-wasm-return_call) @+45]

Node.js v19.9.0
```
---
 features.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/features.json b/features.json
index 8d68352..c0500e2 100644
--- a/features.json
+++ b/features.json
@@ -212,7 +212,7 @@
 				"saturatedFloatToInt": "12.5",
 				"signExtensions": "12.0",
 				"simd": "16.4",
-				"tailCall": ["flag", "Requires flag `--experimental-wasm-return-call`"],
+				"tailCall": "20.0",
 				"threads": "16.4",
 				"typeReflection": ["flag", "Requires flag `--experimental-wasm-type-reflection`"]
 			}