[INFO] crate thunk 0.3.0 is already in cache
[INFO] extracting crate thunk 0.3.0 into work/ex/beta-1.37-6/sources/1.36.0/reg/thunk/0.3.0
[INFO] extracting crate thunk 0.3.0 into work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/thunk/0.3.0
[INFO] validating manifest of thunk-0.3.0 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 thunk-0.3.0 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 thunk-0.3.0
[INFO] finished frobbing thunk-0.3.0
[INFO] frobbed toml for thunk-0.3.0 written to work/ex/beta-1.37-6/sources/1.36.0/reg/thunk/0.3.0/Cargo.toml
[INFO] started frobbing thunk-0.3.0
[INFO] finished frobbing thunk-0.3.0
[INFO] frobbed toml for thunk-0.3.0 written to work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/thunk/0.3.0/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 thunk-0.3.0 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-4/1.36.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/1.36.0/reg/thunk/0.3.0:/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] e8521ddeb989446841c258db848b3a5db1968727ec580a8841028f57859ee3c1
[INFO] running `"docker" "start" "-a" "e8521ddeb989446841c258db848b3a5db1968727ec580a8841028f57859ee3c1"`
[INFO] [stderr]    Compiling thunk v0.3.0 (/opt/crater/workdir)
[INFO] [stderr] warning: unused doc comment
[INFO] [stderr]    --> src/sync.rs:260:13
[INFO] [stderr]     |
[INFO] [stderr] 260 |             /// If the `AtomicThunk` is evaluated, do nothing.
[INFO] [stderr]     |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 261 |             THUNK_EVALUATED => {}
[INFO] [stderr]     |             --------------------- rustdoc does not generate documentation for match arms
[INFO] [stderr]     |
[INFO] [stderr]     = note: #[warn(unused_doc_comments)] on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused doc comment
[INFO] [stderr]    --> src/sync.rs:263:13
[INFO] [stderr]     |
[INFO] [stderr] 263 | /             /// If the `AtomicThunk` is `LOCKING` or `LOCKED`, wait until the thunk is
[INFO] [stderr] 264 | |             /// done evaluating and then return a reference to the inner value.
[INFO] [stderr]     | |_______________________________________________________________________________^
[INFO] [stderr] 265 |               THUNK_LOCKING | THUNK_LOCKED => unsafe { self.besiege() },
[INFO] [stderr]     |               --------------------------------------------------------- rustdoc does not generate documentation for match arms
[INFO] [stderr] 
[INFO] [stderr] warning: unused doc comment
[INFO] [stderr]    --> src/sync.rs:267:13
[INFO] [stderr]     |
[INFO] [stderr] 267 | /             /// Only `THUNK_DEFERRED`, `THUNK_EVALUATED`, `THUNK_LOCKING`, and
[INFO] [stderr] 268 | |             /// `THUNK_LOCKED` are valid values of the flag.
[INFO] [stderr]     | |____________________________________________________________^
[INFO] [stderr] 269 | /             THUNK_INVALIDATED |
[INFO] [stderr] 270 | |             _ => unsafe { unreachable() },
[INFO] [stderr]     | |_________________________________________- rustdoc does not generate documentation for match arms
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]   --> src/lib.rs:20:1
[INFO] [stderr]    |
[INFO] [stderr] 20 | #![feature(fnbox)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]   --> src/lib.rs:21:1
[INFO] [stderr]    |
[INFO] [stderr] 21 | #![feature(untagged_unions)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 2 previous errors
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0554`.
[INFO] [stderr] error: Could not compile `thunk`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "e8521ddeb989446841c258db848b3a5db1968727ec580a8841028f57859ee3c1"`
[INFO] running `"docker" "rm" "-f" "e8521ddeb989446841c258db848b3a5db1968727ec580a8841028f57859ee3c1"`
[INFO] [stdout] e8521ddeb989446841c258db848b3a5db1968727ec580a8841028f57859ee3c1