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[DOCS] GC tutorial: wat2wasm and --invoke commands fail #316
Description
Description
The Garbage Collection tutorial cannot be completed by following its commands on Ubuntu 24.04. Both the compile instructions and the run commands fail.
The prerequisites install WABT with sudo apt install -y wabt. After copying the struct example into point.wat, the documented compile command fails:
$ wat2wasm point.wat -o point.wasm
point.wat:2:17: error: struct not allowed
The array example fails too:
$ wat2wasm array.wat -o array.wasm
array.wat:2:21: error: array type not allowed
These errors reproduce with Ubuntu's WABT 1.0.34 and upstream WABT 1.0.42. Adding GC feature flags does not make these examples compile. For example, WABT 1.0.42 with --enable-all reports:
point.wat:8:8: error: unexpected token "struct.new", expected an expr.
After compiling the same WAT with wasm-tools parse instead, the documented run commands fail on WasmEdge 0.18.1:
$ wasmedge --invoke make_point point.wasm
unknown option: invoke
$ wasmedge --invoke array_example array.wasm
unknown option: invoke
Both commands exit 1 rather than printing the documented 99 and 42.
Commands that complete the examples:
| Step | Current command | Result | Working replacement | Result |
|---|---|---|---|---|
| Struct compilation | wat2wasm point.wat -o point.wasm |
struct not allowed |
wasm-tools parse point.wat -o point.wasm |
Exit 0 |
| Struct execution | wasmedge --invoke make_point point.wasm |
unknown option: invoke |
wasmedge --reactor point.wasm make_point |
Exit 0, 99 |
| Array compilation | wat2wasm array.wat -o array.wasm |
array type not allowed |
wasm-tools parse array.wat -o array.wasm |
Exit 0 |
| Array execution | wasmedge --invoke array_example array.wasm |
unknown option: invoke |
wasmedge --reactor array.wasm array_example |
Exit 0, 42 |
The WAT and expected output can stay unchanged. The prerequisites need a compiler that supports the examples' GC syntax, such as wasm-tools.
Additional information
- Docs commit:
510876021be352dbb19be5f44e4131343a4a32ba. - Clean
ubuntu:24.04container, Linux x86_64. - WABT 1.0.34 from apt and upstream WABT 1.0.42.
- WasmEdge 0.18.1 installed using its official installer.
- Replacement parser: wasm-tools 1.262.0.
- Related: Feature Request: Add a chapter about the Wasm GC proposal #235 requests GC documentation. This issue concerns the existing tutorial's commands.
--invoke does not appear anywhere in the WasmEdge CLI's history; the CLI guide calls exported functions with wasmedge --reactor <module> <function>.
I have a fix ready and will open a PR.
Assisted by Claude Opus 5.5 and GPT 6.1 sol.
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