Allow specifying crate-type on examples

[jethrogb]

I'm working on a crate that is specifically designed to be used in libraries. As such, I want to include some example libraries. It is not currently possible to have cargo build these, as the crate-type is ignored in the [[examples]] section.

[alexcrichton]

In theory, though, you could have the whole example with just a fn main() {} at the bottom, though, right?

[jethrogb]

That would work if this crate can be linked into an executable, which it can't. I need to specify the crate type so that the linker gets invoked correctly.

[alexcrichton]

I guess I'm a little confused on the use case here, can you elaborate a little more on what use case you have in mind?

That being said this seems pretty innocuous to add support for.

[alexcrichton]

Also tagging as E-easy as this should be pretty approachable!

[jethrogb]

I guess I'm a little confused on the use case here, can you elaborate a little more on what use case you have in mind?

When trying to link this crate+this example, there will be unresolved symbols (by design). This is fine for a library, but not for an executable.

[alexcrichton]

Ah ok, that makes sense to me!

[KalitaAlexey]

I am working on it.

[retep998]

This would also be quite useful with cdylib and staticlib crate types as well, not just rlib.