[INFO] updating cached repository learn-you-a-rust/references
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/learn-you-a-rust/references
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/learn-you-a-rust/references" "work/ex/beta-1.37-6/sources/1.36.0/gh/learn-you-a-rust/references"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.37-6/sources/1.36.0/gh/learn-you-a-rust/references'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/learn-you-a-rust/references" "work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/learn-you-a-rust/references"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/learn-you-a-rust/references'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 6ff4ef6f42c370e58278100c0a8e74b01e4b82a9
[INFO] sha for GitHub repo learn-you-a-rust/references: 6ff4ef6f42c370e58278100c0a8e74b01e4b82a9
[INFO] validating manifest of learn-you-a-rust/references on toolchain 1.36.0
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of learn-you-a-rust/references on toolchain beta-2019-07-23
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing learn-you-a-rust/references
[INFO] finished frobbing learn-you-a-rust/references
[INFO] frobbed toml for learn-you-a-rust/references written to work/ex/beta-1.37-6/sources/1.36.0/gh/learn-you-a-rust/references/Cargo.toml
[INFO] started frobbing learn-you-a-rust/references
[INFO] finished frobbing learn-you-a-rust/references
[INFO] frobbed toml for learn-you-a-rust/references written to work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/learn-you-a-rust/references/Cargo.toml
[INFO] crate learn-you-a-rust/references already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing learn-you-a-rust/references against 1.36.0 for beta-1.37-6
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.37-6/worker-1/1.36.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/1.36.0/gh/learn-you-a-rust/references:/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" "+1.36.0" "build" "--frozen"`
[INFO] [stdout] e0da8c1599533ceaf063a7d0582e25fb07e5735c809c88c2bdfa594cdc73a3ea
[INFO] running `"docker" "start" "-a" "e0da8c1599533ceaf063a7d0582e25fb07e5735c809c88c2bdfa594cdc73a3ea"`
[INFO] [stderr]    Compiling references v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] warning: unused variable: `s4`
[INFO] [stderr]   --> src/main.rs:19:9
[INFO] [stderr]    |
[INFO] [stderr] 19 |     let s4 = &s1;        // <-- if this ref exists, &mut s1 refs can't be used 
[INFO] [stderr]    |         ^^ help: consider prefixing with an underscore: `_s4`
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(unused_variables)] on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `s2`
[INFO] [stderr]   --> src/main.rs:31:13
[INFO] [stderr]    |
[INFO] [stderr] 31 |         let s2 = &mut s1;
[INFO] [stderr]    |             ^^ help: consider prefixing with an underscore: `_s2`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `reference_to_nothing`
[INFO] [stderr]   --> src/main.rs:45:9
[INFO] [stderr]    |
[INFO] [stderr] 45 |     let reference_to_nothing = no_dangle();
[INFO] [stderr]    |         ^^^^^^^^^^^^^^^^^^^^ help: consider prefixing with an underscore: `_reference_to_nothing`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `some_string`
[INFO] [stderr]   --> src/main.rs:65:11
[INFO] [stderr]    |
[INFO] [stderr] 65 | fn change(some_string: &String) {
[INFO] [stderr]    |           ^^^^^^^^^^^ help: consider prefixing with an underscore: `_some_string`
[INFO] [stderr] 
[INFO] [stderr] warning: function is never used: `change`
[INFO] [stderr]   --> src/main.rs:65:1
[INFO] [stderr]    |
[INFO] [stderr] 65 | fn change(some_string: &String) {
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(dead_code)] on by default
[INFO] [stderr] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.41s
[INFO] running `"docker" "inspect" "e0da8c1599533ceaf063a7d0582e25fb07e5735c809c88c2bdfa594cdc73a3ea"`
[INFO] running `"docker" "rm" "-f" "e0da8c1599533ceaf063a7d0582e25fb07e5735c809c88c2bdfa594cdc73a3ea"`
[INFO] [stdout] e0da8c1599533ceaf063a7d0582e25fb07e5735c809c88c2bdfa594cdc73a3ea
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.37-6/worker-1/1.36.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/1.36.0/gh/learn-you-a-rust/references:/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" "+1.36.0" "test" "--frozen" "--no-run"`
[INFO] [stdout] 9ff722f983fd2c278e18041eebb0b87ac401bf32b76a566cfc20ec4ae513cf7e
[INFO] running `"docker" "start" "-a" "9ff722f983fd2c278e18041eebb0b87ac401bf32b76a566cfc20ec4ae513cf7e"`
[INFO] [stderr]    Compiling references v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] warning: unused variable: `s4`
[INFO] [stderr]   --> src/main.rs:19:9
[INFO] [stderr]    |
[INFO] [stderr] 19 |     let s4 = &s1;        // <-- if this ref exists, &mut s1 refs can't be used 
[INFO] [stderr]    |         ^^ help: consider prefixing with an underscore: `_s4`
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(unused_variables)] on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `s2`
[INFO] [stderr]   --> src/main.rs:31:13
[INFO] [stderr]    |
[INFO] [stderr] 31 |         let s2 = &mut s1;
[INFO] [stderr]    |             ^^ help: consider prefixing with an underscore: `_s2`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `reference_to_nothing`
[INFO] [stderr]   --> src/main.rs:45:9
[INFO] [stderr]    |
[INFO] [stderr] 45 |     let reference_to_nothing = no_dangle();
[INFO] [stderr]    |         ^^^^^^^^^^^^^^^^^^^^ help: consider prefixing with an underscore: `_reference_to_nothing`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `some_string`
[INFO] [stderr]   --> src/main.rs:65:11
[INFO] [stderr]    |
[INFO] [stderr] 65 | fn change(some_string: &String) {
[INFO] [stderr]    |           ^^^^^^^^^^^ help: consider prefixing with an underscore: `_some_string`
[INFO] [stderr] 
[INFO] [stderr] warning: function is never used: `change`
[INFO] [stderr]   --> src/main.rs:65:1
[INFO] [stderr]    |
[INFO] [stderr] 65 | fn change(some_string: &String) {
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(dead_code)] on by default
[INFO] [stderr] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.44s
[INFO] running `"docker" "inspect" "9ff722f983fd2c278e18041eebb0b87ac401bf32b76a566cfc20ec4ae513cf7e"`
[INFO] running `"docker" "rm" "-f" "9ff722f983fd2c278e18041eebb0b87ac401bf32b76a566cfc20ec4ae513cf7e"`
[INFO] [stdout] 9ff722f983fd2c278e18041eebb0b87ac401bf32b76a566cfc20ec4ae513cf7e
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.37-6/worker-1/1.36.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/1.36.0/gh/learn-you-a-rust/references:/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" "+1.36.0" "test" "--frozen"`
[INFO] [stdout] 3c86ac4dae61e274173cf9dc2471f11eac0110a16d66ee06f7eb7dcfe64f7ad3
[INFO] running `"docker" "start" "-a" "3c86ac4dae61e274173cf9dc2471f11eac0110a16d66ee06f7eb7dcfe64f7ad3"`
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.01s
[INFO] [stderr]      Running /opt/crater/target/debug/deps/references-64828a55ab30d411
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
[INFO] [stdout] 
[INFO] running `"docker" "inspect" "3c86ac4dae61e274173cf9dc2471f11eac0110a16d66ee06f7eb7dcfe64f7ad3"`
[INFO] running `"docker" "rm" "-f" "3c86ac4dae61e274173cf9dc2471f11eac0110a16d66ee06f7eb7dcfe64f7ad3"`
[INFO] [stdout] 3c86ac4dae61e274173cf9dc2471f11eac0110a16d66ee06f7eb7dcfe64f7ad3