gps doesn't handle directories with multiple packages

[adg]

A common idiom for packages with generated code is to include a file named something like gen.go that contains

package main

// +build ignore

...

These are then invoked with go generate. When doing a gps.ListPackages, the analysis of that package will fail with a *build.MultiplePackageError.

We need to be able to handle this. Should build ignore be handled specially?

[adg]

@freeformz points out that this issue is not specific to ignore, although it is the most common.

[jessfraz]

yeah we hit something like this too: sdboyer/gps#147 idk if related I had a generate build ignore file in a dir too

[sdboyer]

I actually did write special handling for this because of this idiom, and it should be working now. The problem, as someone just recently raised in the gps queue (sdboyer/gps#138), is that it doesn't work if there's > 1 file with package main and // +build ignore.

I definitely want proper support for this idiom, which means making it work no matter how many such files exist. As that issue describes, there's a hack we could implement to fix things "for now," though doing it properly is part of a larger planned refactor.

What's interesting about this case, and what I don't feel like I there's an obvious right answer to, is whether the imports from such main/ignored files should be included in analysis.

[sdboyer]

Should be all fixed up now