[INFO] updating cached repository mattmacleod/kern
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/mattmacleod/kern
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/mattmacleod/kern" "work/ex/beta-1.38-1/sources/1.37.0/gh/mattmacleod/kern"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/mattmacleod/kern'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/mattmacleod/kern" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/mattmacleod/kern"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/mattmacleod/kern'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 704ca2bc73d8bc568f7f44b6a67d61976c8612da
[INFO] sha for GitHub repo mattmacleod/kern: 704ca2bc73d8bc568f7f44b6a67d61976c8612da
[INFO] validating manifest of mattmacleod/kern 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 mattmacleod/kern 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 mattmacleod/kern
[INFO] finished frobbing mattmacleod/kern
[INFO] frobbed toml for mattmacleod/kern written to work/ex/beta-1.38-1/sources/1.37.0/gh/mattmacleod/kern/Cargo.toml
[INFO] started frobbing mattmacleod/kern
[INFO] finished frobbing mattmacleod/kern
[INFO] frobbed toml for mattmacleod/kern written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/mattmacleod/kern/Cargo.toml
[INFO] crate mattmacleod/kern 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] [stderr] error: the lock file /mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/gh/mattmacleod/kern/Cargo.lock needs to be updated but --locked was passed to prevent this
[INFO] the lockfile is outdated, regenerating it
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] testing mattmacleod/kern 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-1/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/gh/mattmacleod/kern:/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] 7c0b02b1e472b5e44209b86da5d9861d2e2db7cd34e4e5ac7dab97ac812bf2e3
[INFO] running `"docker" "start" "-a" "7c0b02b1e472b5e44209b86da5d9861d2e2db7cd34e4e5ac7dab97ac812bf2e3"`
[INFO] [stderr]    Compiling kern v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] error: cannot find macro `format!` in this scope
[INFO] [stderr]   --> src/lib.rs:20:13
[INFO] [stderr]    |
[INFO] [stderr] 20 |     let s = format!("{}", res);
[INFO] [stderr]    |             ^^^^^^
[INFO] [stderr] 
[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(no_std)]
[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(lang_items, asm, const_fn, collections)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: unused import: `core::fmt::Display`
[INFO] [stderr]  --> src/lib.rs:7:5
[INFO] [stderr]   |
[INFO] [stderr] 7 | use core::fmt::Display;
[INFO] [stderr]   |     ^^^^^^^^^^^^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: #[warn(unused_imports)] on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused import: `core::fmt::Formatter`
[INFO] [stderr]  --> src/lib.rs:8:5
[INFO] [stderr]   |
[INFO] [stderr] 8 | use core::fmt::Formatter;
[INFO] [stderr]   |     ^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0522]: definition of an unknown language item: `panic_fmt`
[INFO] [stderr]   --> src/lib.rs:54:1
[INFO] [stderr]    |
[INFO] [stderr] 54 | #[lang = "panic_fmt"] fn panic_fmt() -> ! { loop {} }
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^ definition of unknown language item `panic_fmt`
[INFO] [stderr] 
[INFO] [stderr] error: `#[panic_handler]` function required, but not found
[INFO] [stderr] 
[INFO] [stderr] warning: unused import: `core::fmt::Write`
[INFO] [stderr]  --> src/lib.rs:9:5
[INFO] [stderr]   |
[INFO] [stderr] 9 | use core::fmt::Write;
[INFO] [stderr]   |     ^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 5 previous errors
[INFO] [stderr] 
[INFO] [stderr] Some errors have detailed explanations: E0522, E0554.
[INFO] [stderr] For more information about an error, try `rustc --explain E0522`.
[INFO] [stderr] error: Could not compile `kern`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "7c0b02b1e472b5e44209b86da5d9861d2e2db7cd34e4e5ac7dab97ac812bf2e3"`
[INFO] running `"docker" "rm" "-f" "7c0b02b1e472b5e44209b86da5d9861d2e2db7cd34e4e5ac7dab97ac812bf2e3"`
[INFO] [stdout] 7c0b02b1e472b5e44209b86da5d9861d2e2db7cd34e4e5ac7dab97ac812bf2e3