compile-fail/recursion.rs uses a dummy span with an expansion id of -2

[Manishearth]

Found whilst testing #20032

From the test:

// We also get a second error message at the top of file (dummy
// span). This is not helpful, but also kind of annoying to prevent,
// so for now just live with it, since we also get a second message
// that is more helpful.

This should probably be fixed. For now (when #20032 lands) I've made that test ignore command line spans.

I'll work on tracking back this span and trying to fix this.

[Manishearth]

nikomatsakis@9e4e882

[nikomatsakis]

I don't understand. I know the source of that particular error, are you saying that we get another? The source of that error is that we don't pass a span into librustc_trans::common::type_is_sized() and thus have to gin one up.

[Manishearth]

(I'm working on this, got some ideas as to why it's happening)