Docmatic fails when a dependency of the tested crate changed

[konstin]

When changing dependencies in pyo3, docmatic will reproducibly fail to build the doc tests.

This can be easily reproduced by pinning something irrelevant (in this, log 0.4.2) to a lower version: (Requires nightly rust)

git clone https://github.com/PyO3/pyo3
cd pyo3
cargo test
sed -i -e 's/"0.4"/"=0.4.1"/' Cargo.toml
cargo test

The second test run will print a lot of errors like the following:

---- guide/src/function.md - Python_Function (line 36) stdout ----
error[E0464]: multiple matching crates for `pyo3`
 --> guide/src/function.md:40:1
  |
5 | extern crate pyo3;
  | ^^^^^^^^^^^^^^^^^^
  |
  = note: candidates:
          crate `pyo3`: /home/konsti/doc/target/debug/deps/libpyo3-3df255959ab0361f.rlib
          crate `pyo3`: /home/konsti/doc/target/debug/deps/libpyo3-1891f9f7b2b3eea4.rlib

I had this happen on multiple nightlies, so I'm pretty sure it's not a bug in nightly.

[epage]

Thanks for reporting this! I keep forgetting to myself.

The terrible workaround for this is:

rm -rf target/debug/deps/*pyo3* 

See liquid's .travis.yml

This is a problem that has also long plagued skeptic, see budziq/rust-skeptic#18.

[epage]

The root of the issue is we don't pass --extern for this crate to disambiguate it once the build has created different versions of it.

I wonder if we could do a build using escargot to capture what rlibs are created and pass each one in.