[INFO] updating cached repository arturts/ProjectEuler-Rust
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/arturts/ProjectEuler-Rust
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/arturts/ProjectEuler-Rust" "work/ex/beta-1.38-1/sources/1.37.0/gh/arturts/ProjectEuler-Rust"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/arturts/ProjectEuler-Rust'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/arturts/ProjectEuler-Rust" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/arturts/ProjectEuler-Rust"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/arturts/ProjectEuler-Rust'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 0d6b5ae9979049d6258101fbe55eb91fefc7d39d
[INFO] sha for GitHub repo arturts/ProjectEuler-Rust: 0d6b5ae9979049d6258101fbe55eb91fefc7d39d
[INFO] validating manifest of arturts/ProjectEuler-Rust on toolchain 1.37.0
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of arturts/ProjectEuler-Rust on toolchain beta-2019-08-13
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing arturts/ProjectEuler-Rust
[INFO] finished frobbing arturts/ProjectEuler-Rust
[INFO] frobbed toml for arturts/ProjectEuler-Rust written to work/ex/beta-1.38-1/sources/1.37.0/gh/arturts/ProjectEuler-Rust/Cargo.toml
[INFO] started frobbing arturts/ProjectEuler-Rust
[INFO] finished frobbing arturts/ProjectEuler-Rust
[INFO] frobbed toml for arturts/ProjectEuler-Rust written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/arturts/ProjectEuler-Rust/Cargo.toml
[INFO] crate arturts/ProjectEuler-Rust already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing arturts/ProjectEuler-Rust against 1.37.0 for beta-1.38-1
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.38-1/worker-3/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/gh/arturts/ProjectEuler-Rust:/opt/crater/workdir:ro,Z" "-v" "/mnt/big/crater/work/local/cargo-home:/opt/crater/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/local/rustup-home:/opt/crater/rustup-home:ro,Z" "-e" "USER_ID=1000" "-e" "SOURCE_DIR=/opt/crater/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/crater/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/crater/cargo-home" "-e" "RUSTUP_HOME=/opt/crater/rustup-home" "-w" "/opt/crater/workdir" "-m" "1536M" "--network" "none" "rustops/crates-build-env" "/opt/crater/cargo-home/bin/cargo" "+1.37.0" "build" "--frozen"`
[INFO] [stdout] ef0fd5a66e725164de5bb58a1863b0375a6503fe5d5d081cfa127fd765bdd2ca
[INFO] running `"docker" "start" "-a" "ef0fd5a66e725164de5bb58a1863b0375a6503fe5d5d081cfa127fd765bdd2ca"`
[INFO] [stderr]    Compiling project_euler v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]  --> src/lib.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(step_by)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0600]: cannot apply unary operator `-` to type `usize`
[INFO] [stderr]  --> src/problem_4/mod.rs:4:36
[INFO] [stderr]   |
[INFO] [stderr] 4 |     for num_a in (999..99).step_by(-1) {
[INFO] [stderr]   |                                    ^^ cannot apply unary operator `-`
[INFO] [stderr]   |
[INFO] [stderr]   = note: unsigned values cannot be negated
[INFO] [stderr] 
[INFO] [stderr] error[E0600]: cannot apply unary operator `-` to type `usize`
[INFO] [stderr]  --> src/problem_4/mod.rs:5:42
[INFO] [stderr]   |
[INFO] [stderr] 5 |         for num_b in (num_a..99).step_by(-1) {
[INFO] [stderr]   |                                          ^^ cannot apply unary operator `-`
[INFO] [stderr]   |
[INFO] [stderr]   = note: unsigned values cannot be negated
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 3 previous errors
[INFO] [stderr] 
[INFO] [stderr] Some errors have detailed explanations: E0554, E0600.
[INFO] [stderr] For more information about an error, try `rustc --explain E0554`.
[INFO] [stderr] error: Could not compile `project_euler`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "ef0fd5a66e725164de5bb58a1863b0375a6503fe5d5d081cfa127fd765bdd2ca"`
[INFO] running `"docker" "rm" "-f" "ef0fd5a66e725164de5bb58a1863b0375a6503fe5d5d081cfa127fd765bdd2ca"`
[INFO] [stdout] ef0fd5a66e725164de5bb58a1863b0375a6503fe5d5d081cfa127fd765bdd2ca