Fix 32-bit Windows compile error

[andreastt]

https://travis-ci.org/mozilla/geckodriver/builds/163755698

[andreastt]

Filed alexcrichton/port-of-rust#5.

[andreastt]

The port-of-rust Docker image we are building is using Nightly which has a bug causing the i686 Windows build to fail.

Unfortunately Rust stable does not have the i686-pc-windows-gnu target, and the the same bug that is in Nightly affects Beta.

I think the short-term solution here is to fork the Dockerfile and pin it to a known-good version of Rust (probably beta by this point), so that we can make a release early next week.

[andreastt]

It looks like the bug in nightly was fixed in rust-lang/rust#36866, but there are build issues with Rust for iOS, which means there have been no nightly builds yet with this fix in it.

[andreastt]

It looks like cross-compilation for 64-bit Windows is also failing, but isn’t surfacing on geckodriver’s master builds because they use a cached Rust Nightly version which is known to be good:

+rustc -V
rustc 1.13.0-beta.1 (cbbeba430 2016-09-28)

https://travis-ci.org/andreastt/geckodriver/builds/164048072

[andreastt]

The x86_64-pc-windows-gnu cross-compile also fails on stable: https://travis-ci.org/andreastt/geckodriver/jobs/164685055

[andreastt]

Right, after many hours of digging I’ve found that this is probably a regression Travis, our CI. We rely on the container infrastructure they provide to get faster builds. Up until around 2016-09-21 the containers provided were running Ubuntu trusty, the distribution version we had requested. Sometime in the days after this Travis started providing Ubuntu precise container images on a trusty host OS.

Ubuntu precise obviously have a much older gcc version than trusty, and linking probably fails because it produces something Rust can’t use. I confirmed this through using a custom container on Travis, which fixes our 64-bit build.

The 32-bit build is failing because of rust-lang/rust#36866, but we should be able to circumvent this by pinning the Rust Nightly version like this:

rustup override set nightly-2016-09-21

Which also, I found, can be used for the rustup installer:

curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain=nightly-2016-09-21

[lock]

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