Judge type error when compiling go source code to wasm

[elvin-du]

My cmds are as follows。

tinygo build -target wasm -o main.wasm main.go
# main.go
main.go:33:55: cannot use length (variable of type int) as uintptr value in struct literal

my go codes as follows:

//go:export Get
func Get() {
....
	length := len([]byte("dmx"))

	str := reflect.StringHeader{Data: uintptr(ptr), Len: length}
	.....
}

reflect.StringHeader definition as follows:

type StringHeader struct {
	Data uintptr
	Len  int
}

Len type is int。

[niaow]

So the issues here is that the definition of StringHeader is different between Go and TinyGo at the moment. TinyGo defines StringHeader as:

type StringHeader struct {
	Data uintptr
	Len  uintptr
}

We may need to try to make some hacky workaround to get this to work. . .

[aykevl]

See the documentation (emphasis mine):

StringHeader is the runtime representation of a string. It cannot be used safely or portably and its representation may change in a later release. Moreover, the Data field is not sufficient to guarantee the data it references will not be garbage collected, so programs must keep a separate, correctly typed pointer to the underlying data.

So technically the code that fails to compile is inherently unportable. However, the the only architecture where int and uintptr have a different size is on AVR. Perhaps we can change the type on non-AVR systems to be int for compatibility?

[deadprogram]

I'm not sure if this is a bug exactly. What would be the correct category for this issue?

[deadprogram]

What is the status of this issue/question?

[deadprogram]

I am going to close this due to age and that it is somewhat ambiguous. Please reopen if needed. Thank you.

[sananguliyev]

I have the same issue:

# github.com/cespare/xxhash
../../../go/pkg/mod/github.com/cespare/[email protected]/xxhash_unsafe.go:27:11: cannot use len(s) (value of type int) as uintptr value in assignment
../../../go/pkg/mod/github.com/cespare/[email protected]/xxhash_unsafe.go:28:11: cannot use len(s) (value of type int) as uintptr value in assignment

[aykevl]

@sananguliyev please see https://tinygo.org/docs/guides/compatibility/#reflectsliceheader-and-reflectstringheader.