Injecting build time variables with ldflags not working for target wasm

[evilnoxx]

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As the title says, setting a variable with -ldflags="-X '<.....>'" doesn't seem to work if the target is set to wasm

I've tried it with a simple example:

package main

import "fmt"

var version = "unknown"

func main() {
	fmt.Printf("%s\n", version)
}

compiled with: tinygo build -ldflags="-X 'main.version=whatever'" -target wasm

But after loading the wasm in a browser, the console shows "unknown" instead of "whatever".

The same approach to setting variables, works fine if i use -target wasi, and run the wasm with wasmedge.

Am I doing something wrong, or is this a bug?

tinygo version 0.23.0 darwin/amd64 (using go version go1.18.2 and LLVM version 14.0.0)

[aykevl]

It works if you remove the default value for the value. For example:

var version string

Doing this with an initializer is not currently supported.

[evilnoxx]

The variables get initialized now.

Thank you for the help.

[dgryski]

Is this documented sufficiently already or do we need to fix it? If the docs are up-to-date, can we close this bug?

[aykevl]

I don't think this is documented anywhere for TinyGo. It's just a side effect from how the x/tools/go/ssa package works and how this feature is implemented in TinyGo. Not sure what to do about it, apart from fixing this case in the compiler.

[deadprogram]

Please see https://github.com/tinygo-org/tinygo-site/pull/357

[deadprogram]

This is part of the v0.28 release so now closing this issue. Thanks!