Bug: Magefile in .mage subdirectory stopped working in Go 1.16

[mirogta]

We are now using Magefile quite extensively in majority of our projects.

In order to separate it from the app code, we put the magefile.go or other mage-related files into a .mage subdirectory and configure the mage run like this in our Makefile:

MAGE = go run .mage/mage.go -d .mage -w .

help:
	@$(MAGE)

mage:
	@$(MAGE) $(args)

.DEFAULT:
	@$(MAGE) -v $@

The .mage\mage.go…

// +build ignore

package main

import (
	"os"
	"github.com/magefile/mage/mage"
)

func main() { os.Exit(mage.Main()) }

… is just a wrapper around the magefile.go

// +build mage

package main
…
// Build…
func Build() {
…
}

// Clean…
func Clean() {
…
}

The .DEFAULT target allows us to run any mage target like a make target, so we can run e.g. make build instead of make mage args="build"

This has stopped working after upgrading to Go 1.16.

The problem is this line:

cmd = exec.Command(goCmd, "list", "-tags=mage", "-e", "-f", `{{join .GoFiles "||"}}`)

It doesn't find any Go files:

No .go files marked with the mage build tag in this directory.

How to reproduce:

• create a magefile.go in a subdirectory, e.g. .mage\magefile.go
• run mage
• observe the error

Expected behaviour:

• mage should keep working even if the mage files are in a subdirectory

[mirogta]

Looks like the problem is this:

$ …/<module repo>/.mage> go list .
malformed import path "<module>/.mage": leading dot in path element

I have simply renamed the .mage directory to mage and things have started working. I'm trying to find out where is this breaking change coming from in Go 1.16, but if anyone has a clue how to make it still work with .mage it would be much appreciated. Otherwise we should yet again modify the build steps in all our repos :-(

[mirogta]

I think I've found the reason here:

A valid path element is a non-empty string made up of ASCII letters, ASCII digits, and limited ASCII punctuation: - . _ and ~. It must not begin or end with a dot (U+002E), nor contain two dots in a row.

[mirogta]

The problem is in Go, not in Mage… will close this issue.

[ntrrg]

Hey! sorry for commenting this closed issue, but could you try creating a go.mod file in .mage? that way even the magefiles dependecies are in their own module