[INFO] crate tao-of-rust 1.0.2 is already in cache
[INFO] extracting crate tao-of-rust 1.0.2 into work/ex/beta-1.37-6/sources/1.36.0/reg/tao-of-rust/1.0.2
[INFO] extracting crate tao-of-rust 1.0.2 into work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/tao-of-rust/1.0.2
[INFO] validating manifest of tao-of-rust-1.0.2 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 tao-of-rust-1.0.2 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 tao-of-rust-1.0.2
[INFO] finished frobbing tao-of-rust-1.0.2
[INFO] frobbed toml for tao-of-rust-1.0.2 written to work/ex/beta-1.37-6/sources/1.36.0/reg/tao-of-rust/1.0.2/Cargo.toml
[INFO] started frobbing tao-of-rust-1.0.2
[INFO] finished frobbing tao-of-rust-1.0.2
[INFO] frobbed toml for tao-of-rust-1.0.2 written to work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/tao-of-rust/1.0.2/Cargo.toml
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[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 tao-of-rust-1.0.2 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-6/1.36.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/1.36.0/reg/tao-of-rust/1.0.2:/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] 2d52ba3c860df5fb1f49b5e2e5dea54d62d977992a00163e42147c4fdc050fa4
[INFO] running `"docker" "start" "-a" "2d52ba3c860df5fb1f49b5e2e5dea54d62d977992a00163e42147c4fdc050fa4"`
[INFO] [stderr]    Compiling structopt v0.2.18
[INFO] [stderr]    Compiling failures_crate v0.1.0
[INFO] [stderr]    Compiling csv_challenge v0.1.0
[INFO] [stderr]    Compiling tao-of-rust v1.0.2 (/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(const_fn)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]  --> src/lib.rs:2:1
[INFO] [stderr]   |
[INFO] [stderr] 2 | #![feature(never_type)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]  --> src/lib.rs:3:1
[INFO] [stderr]   |
[INFO] [stderr] 3 | #![feature(specialization)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]  --> src/lib.rs:4:1
[INFO] [stderr]   |
[INFO] [stderr] 4 | #![feature(unboxed_closures, fn_traits)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: unnecessary parentheses around `for` head expression
[INFO] [stderr]    --> src/ch02/primitives.rs:170:14
[INFO] [stderr]     |
[INFO] [stderr] 170 |     for i in (1..5) {
[INFO] [stderr]     |              ^^^^^^ help: remove these parentheses
[INFO] [stderr]     |
[INFO] [stderr]     = note: #[warn(unused_parens)] on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unnecessary parentheses around `for` head expression
[INFO] [stderr]    --> src/ch02/primitives.rs:173:14
[INFO] [stderr]     |
[INFO] [stderr] 173 |     for i in (1..=5) {
[INFO] [stderr]     |              ^^^^^^^ help: remove these parentheses
[INFO] [stderr] 
[INFO] [stderr] warning: unnecessary parentheses around `if` condition
[INFO] [stderr]   --> src/ch02/structs.rs:58:23
[INFO] [stderr]    |
[INFO] [stderr] 58 |       let gender = if (self.gender == 1) {"boy"} else {"girl"};
[INFO] [stderr]    |                       ^^^^^^^^^^^^^^^^^^ help: remove these parentheses
[INFO] [stderr] 
[INFO] [stderr] warning: the item `Drop` is imported redundantly
[INFO] [stderr]   --> src/ch04/raii.rs:92:9
[INFO] [stderr]    |
[INFO] [stderr] 92 |     use std::ops::Drop;
[INFO] [stderr]    |         ^^^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(unused_imports)] on by default
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 4 previous errors
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0554`.
[INFO] [stderr] error: Could not compile `tao-of-rust`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "2d52ba3c860df5fb1f49b5e2e5dea54d62d977992a00163e42147c4fdc050fa4"`
[INFO] running `"docker" "rm" "-f" "2d52ba3c860df5fb1f49b5e2e5dea54d62d977992a00163e42147c4fdc050fa4"`
[INFO] [stdout] 2d52ba3c860df5fb1f49b5e2e5dea54d62d977992a00163e42147c4fdc050fa4