`GetFunction` returns `func(...interface {}) (interface {}, error)` not `func() (string, error)`

[Alex Collins]

I don't understand why this is happening. I'm compiling this function:

//export getDocument
func getDocument() string {
	return ""
}

Using this command

tinygo build -o ../module.wasm -wasm-abi=generic -target=wasi .

When I execute Exports.GetFunction("getDocument") I get this signature func(...interface {}) (interface {}, error).

That is really weird to me.

If I add a single argument to

//export getDocument
func getDocument(arg string) string {
	return ""
}

I now get a Missing 2 argument(s) when calling the function; Expected 3 argument(s), received 1 error.

What is going on, this makes no sense to me. Why has it suddenly gone from zero args to three args?

[Alex Collins]

Ok, so presumably this is a tinygo bug.

wasmer inspect module.wasm
Type: wasm
Size: 269.0 KB
Imports:
  Functions:
    "wasi_snapshot_preview1"."fd_write": [I32, I32, I32, I32] -> [I32]
    "wasi_snapshot_preview1"."clock_time_get": [I32, I64, I32] -> [I32]
    "wasi_snapshot_preview1"."args_sizes_get": [I32, I32] -> [I32]
    "wasi_snapshot_preview1"."args_get": [I32, I32] -> [I32]
    "wasi_snapshot_preview1"."environ_get": [I32, I32] -> [I32]
    "wasi_snapshot_preview1"."environ_sizes_get": [I32, I32] -> [I32]
    "wasi_snapshot_preview1"."fd_close": [I32] -> [I32]
    "wasi_snapshot_preview1"."fd_fdstat_get": [I32, I32] -> [I32]
    "wasi_snapshot_preview1"."fd_prestat_get": [I32, I32] -> [I32]
    "wasi_snapshot_preview1"."fd_prestat_dir_name": [I32, I32, I32] -> [I32]
    "wasi_snapshot_preview1"."fd_read": [I32, I32, I32, I32] -> [I32]
    "wasi_snapshot_preview1"."fd_seek": [I32, I64, I32, I32] -> [I32]
    "wasi_snapshot_preview1"."path_open": [I32, I32, I32, I32, I32, I64, I64, I32, I32] -> [I32]
    "wasi_snapshot_preview1"."proc_exit": [I32] -> []
  Memories:
  Tables:
  Globals:
Exports:
  Functions:
    "malloc": [I32] -> [I32]
    "free": [I32] -> []
    "calloc": [I32, I32] -> [I32]
    "realloc": [I32, I32] -> [I32]
    "_start": [] -> []
    "getDocument": [I32, I32, I32] -> []
    "asyncify_start_unwind": [I32] -> []
    "asyncify_stop_unwind": [] -> []
    "asyncify_start_rewind": [I32] -> []
    "asyncify_stop_rewind": [] -> []
    "asyncify_get_state": [] -> [I32]
  Memories:
    "memory": not shared (2 pages..)
  Tables:
  Globals: