When using a pre-compiled static mage binary, the -v flag does not produce the proper output.

Using this simple example:

func ShowVerboseDep() error {
	sh.Run("echo", "hello, mage!")
	return nil
}

func ShowVerbose() error {
	mg.Deps(ShowVerboseDep)
	sh.Run("echo", "goodbye, mage!")
	return nil
}

Output:

$ mage -v showverbose
Running target: ShowVerbose
Running dependency: ShowVerboseDep
exec: echo hello, mage!
hello, mage!
exec: echo goodbye, mage!
goodbye, mage!

$ ./mage -v showverbose
Running target: ShowVerbose
exec: echo hello, mage!
exec: echo goodbye, mage!

We're missing both the shell output and the dependency log lines.

When using the mage command directly, mage sets the MAGEFILE_VERBOSE environment variable based on the -v flag (see here).

However, the generated mage_output_file.go from which the compiled binary is built does no such thing.

This is relevant because both sh and mg inspect the MAGEFILE_VERBOSE environment variable (see here); there doesn't appear to be any other way to signal to these libraries that we want verbose output.

I propose we update the generated mage_output_file.go to set the MAGEFILE_VERBOSE environment variable just like we do for the mage command.