[INFO] updating cached repository jmacmahon/rust-playground
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/jmacmahon/rust-playground
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/jmacmahon/rust-playground" "work/ex/beta-1.38-1/sources/1.37.0/gh/jmacmahon/rust-playground"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/jmacmahon/rust-playground'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/jmacmahon/rust-playground" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/jmacmahon/rust-playground"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/jmacmahon/rust-playground'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] d3ad60100e7e7cc92aa7af86552948d100656ef3
[INFO] sha for GitHub repo jmacmahon/rust-playground: d3ad60100e7e7cc92aa7af86552948d100656ef3
[INFO] validating manifest of jmacmahon/rust-playground 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 jmacmahon/rust-playground 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 jmacmahon/rust-playground
[INFO] finished frobbing jmacmahon/rust-playground
[INFO] frobbed toml for jmacmahon/rust-playground written to work/ex/beta-1.38-1/sources/1.37.0/gh/jmacmahon/rust-playground/Cargo.toml
[INFO] started frobbing jmacmahon/rust-playground
[INFO] finished frobbing jmacmahon/rust-playground
[INFO] frobbed toml for jmacmahon/rust-playground written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/jmacmahon/rust-playground/Cargo.toml
[INFO] crate jmacmahon/rust-playground 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 jmacmahon/rust-playground 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-6/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/gh/jmacmahon/rust-playground:/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] e48c71cb98ded6c5bebc4f86de4ecf176838b6296da403369c65cd9913d2bdfa
[INFO] running `"docker" "start" "-a" "e48c71cb98ded6c5bebc4f86de4ecf176838b6296da403369c65cd9913d2bdfa"`
[INFO] [stderr]    Compiling scratch v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] warning: unused variable: `z`
[INFO] [stderr]  --> src/main.rs:4:9
[INFO] [stderr]   |
[INFO] [stderr] 4 |     let z = &x;
[INFO] [stderr]   |         ^ help: consider prefixing with an underscore: `_z`
[INFO] [stderr]   |
[INFO] [stderr]   = note: #[warn(unused_variables)] on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `x`
[INFO] [stderr]   --> src/main.rs:12:10
[INFO] [stderr]    |
[INFO] [stderr] 12 | fn test2(x: &i32) -> () {
[INFO] [stderr]    |          ^ help: consider prefixing with an underscore: `_x`
[INFO] [stderr] 
[INFO] [stderr] error[E0502]: cannot borrow `x` as immutable because it is also borrowed as mutable
[INFO] [stderr]  --> src/main.rs:4:13
[INFO] [stderr]   |
[INFO] [stderr] 3 |     let y = &mut x;
[INFO] [stderr]   |             ------ mutable borrow occurs here
[INFO] [stderr] 4 |     let z = &x;
[INFO] [stderr]   |             ^^ immutable borrow occurs here
[INFO] [stderr] 5 |     println!("{:?}", y);
[INFO] [stderr]   |                      - mutable borrow later used here
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0502`.
[INFO] [stderr] error: Could not compile `scratch`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "e48c71cb98ded6c5bebc4f86de4ecf176838b6296da403369c65cd9913d2bdfa"`
[INFO] running `"docker" "rm" "-f" "e48c71cb98ded6c5bebc4f86de4ecf176838b6296da403369c65cd9913d2bdfa"`
[INFO] [stdout] e48c71cb98ded6c5bebc4f86de4ecf176838b6296da403369c65cd9913d2bdfa