Tutorial first steps Microsoft Go

I am starting to learn Go following this Microsoft tutorial. The program runs and displays the result as in the tutorial, but the two problems that it is marking me cause me concern. I do not want to continue without understanding what this detail is due to, someone who has also happened to it, or who helps me to know what it is due to, I will be very grateful.

package main

import (
    "fmt"
    "github.com/x0z38/calculator"   
    "rsc.io/quote"
)
func main(){
    total := calculator.Sum(3, 5)
    fmt.Println(total)
    fmt.Println("Version: ", calculator.Version)
    fmt.Println(quote.Hello())
    
}

I leave you the image where the error is marked in red lines in the editor:

I leave the image of the two problems:

According to what I understood is that it does not find those files in any of the mentioned paths, but both files if I have them inside this path: C:\Projects\Go\src.
My GOPATH environment variable is: C:\Projects\Go

Golang has two ways to manage dependencies: old and new. Switching between them is usually done automatically.

Visual Sudio Code tries to check for dependencies using the old way. But I see you have go.mod and go.sum files which means you are using the new way (the Golang module system).

The environment variable GO111MODULE is used to switch between dependency control modes. It has 3 values: auto, on, off. The default is auto.

What you see is just a syntax highlighting problem and not a compilation or execution error.

Ok this is what I did:

First: Run go mod tidy as suggested by Mushroomator in my root project, and it didn't work

Second: remove the GOPATH environment variable, since as JimB commented it is no longer used, and it didn't work either.

Now, this is where I feel a bit confused, because maybe I did what they asked me to do but I don't know how to explain it.

So, it works and no longer shows a syntax error. Delete the GOPATH environment variable, SET GOMODULE111=on, and take out the Projects/Go directory where I have all the files and put it on the desktop and mark this syntax error:

Google
Todo
Imágenes
Noticias
Shopping
Vídeos
Más
Herramientas

Cerca de 1,260,000,000 resultados (0.39 segundos)
Español
Inglés

Now, as you can see, I open VS Code directly in the helloworld directory, and the syntax error disappears, but I wanted to have it open directly from the src directory to see everything I've learned so far:

What I have learned is that you want VS Code (or gopls) to correctly identify a multi-module project. Please refer to this (your are using Go1.18).

And more about go modules.

And go workspace.

Hope those can help you.