rand_core 0.2.2: a compatibility shim around 0.3

[dhardy]

This is necessary where multiple dependencies use differing
versions of rand_core but need the same RngCore etc.

Unfortunately this fails with:

$ cargo test --package rand_core:0.2.2
    Finished dev [unoptimized + debuginfo] target(s) in 0.02s                                                                          
     Running target/debug/deps/rand_core-547dfb477b3cced4

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

   Doc-tests rand_core
error[E0465]: multiple rlib candidates for `rand_core` found
  --> /home/dhardy/projects/rand/rand/rand_core/src/lib.rs:48:1
   |
48 | extern crate rand_core as core3;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
note: candidate #1: /home/dhardy/projects/rand/rand/target/debug/deps/librand_core-f12b3d8f22720790.rlib
  --> /home/dhardy/projects/rand/rand/rand_core/src/lib.rs:48:1
   |
48 | extern crate rand_core as core3;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: candidate #2: /home/dhardy/projects/rand/rand/target/debug/deps/librand_core-c567b6644b6189ab.rlib
  --> /home/dhardy/projects/rand/rand/rand_core/src/lib.rs:48:1
   |
48 | extern crate rand_core as core3;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0463]: can't find crate for `core3`
  --> /home/dhardy/projects/rand/rand/rand_core/src/lib.rs:48:1
   |
48 | extern crate rand_core as core3;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate

error: test failed, to rerun pass '--doc'

I can't work out why — @alexcrichton?

I can work around with rust-lang/cargo#5653 but that requires nightly.

[alexcrichton]

This is a limitation of Cargo where if you depend on the same-named crate you can't use doctests. There's unfortunately no great way to solve this. Eventually when Cargo has stabilized renaming dependencies it should be possible to get this working again

[dhardy]

Thanks for the tip; I disabled doc-tests here. It's a hack, but having this compatibility shim is quite important for users I think.