Golang 1.18 - Exclude package for specific platform

I spent the whole day trying to apply a build constraint in my code:
I have an agent that is designed to work on Windows and Linux, however, I have to interact with the Windows registry (which obviously doesn't have any equivalent on Linux).

My package imports
> "golang.org/x/sys/windows/registry"

The project builds on Windows but not on Linux.
I then learnt about build constraints: //go:build windows (or !linux)
I initially started with // +build windows but I saw that it's for older Go versions.

Here is the header of my package file:

//go:build windows

package utils

import (
	"fmt"
	"log"

	"golang.org/x/sys/windows/registry"
)
...

I use VSCode both on Windows and Linux, I can also see a reference to in my go.mod file.
Any help with this please?

When I run the code above, I still get the following on Linux:

> build golang.org/x/sys/windows/registry: cannot load
> golang.org/x/sys/windows/registry: no Go source files (exit status 1)

Edit: I use the default VSCode tools to compile and run my project, however I have tried: go build . and I still get the same error.
Also, the _windows.go and _linux.go suffixes are not appropriate as the agent would be fore Mac in the future.

I couldn't write the entire thing in the comments but let me know if this small sample helps you:

utils_darwin.go:

package utils

import "fmt"

func Test() {
	fmt.Println("Test from mac")
}

utils_linux.go

package utils

import "fmt"

func Test() {
	fmt.Println("Test from linux")
}

utils_windows.go

package utils

import "fmt"

func Test() {
	fmt.Println("Test from windows")
}

main.go

package main

import "github.com/ninadingole/go-dev-stuff/platform/utils"

func main() {
	utils.Test()
}

When I compile the binary on mac and run it like:

GOOS=darwin go build -o prog ./platform

./prog

Test from mac

I tried to build the binary in docker for linux and got the below output

Test from linux

Let me know if this works for you otherwise I will delete the answer