Allow crates to be published with cyclic dev-dependencies

[Marwes]

In gluon I have the project split up into multiple crates with the intent that users can include only the crates they need if they desire a smaller binary footprint. For convenience I provide a main gluon crate which provides an easy to use interface when one uses all the crates.

While this split works fine for mostly everything I want to use the easy interface when writing documentation tests so I added the gluon crate as a dev-dependency in gluon_vm and this compiles without issue since a little bit back. It does however break when trying to publish gluon_vm as the gluon dev-dependency has not been published yet!

Currently I managed to work around it by specifying a version range but it would be nice if there was a way to publish a group of crates as a whole or to ignore the version check if a dev-dependency does not exist on crates.io (yet).

gluon = { path = "..", version = "<0.6.0, >=0.4.2" } # GLUON

[alexcrichton]

Yeah in general I think we should basically ignore dev-dependencies when we publish. We shouldn't attempt to resolve them, verify they're already published, etc.

[BusyJay]

Maybe dev-dependencies don't have to be shown in the crate's page too.

[matthewkmayer]

I bumped into this issue as well. From what I can tell the workaround above gets us by this for now. 👍

[cramertj]

+1 to this-- it now affects the futures crate.