[INFO] updating cached repository https://github.com/anderejd/extern_attrib
[INFO] running `"git" "-c" "credential.helper=" "-c" "credential.helper=/big/crater/work/cargo-home/bin/git-credential-null" "-c" "remote.origin.fetch=refs/heads/*:refs/heads/*" "fetch" "origin" "--force" "--prune"`
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] a70c0caf5ddb993cde6e65d89b125f168e1d5dcc
[INFO] testing anderejd/extern_attrib against 1.38.0 for beta-1.39-1
[INFO] running `"git" "clone" "work/cache/git-repos/https%3A%2F%2Fgithub.com%2Fanderejd%2Fextern_attrib" "work/builds/worker-2/source"`
[INFO] [stderr] Cloning into 'work/builds/worker-2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/anderejd/extern_attrib on toolchain 1.38.0
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking git repo https://github.com/anderejd/extern_attrib
[INFO] finished tweaking git repo https://github.com/anderejd/extern_attrib
[INFO] tweaked toml for git repo https://github.com/anderejd/extern_attrib written to work/builds/worker-2/source/Cargo.toml
[INFO] crate git repo https://github.com/anderejd/extern_attrib already has a lockfile, it will not be regenerated
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr] error: the lock file /big/crater/work/builds/worker-2/source/Cargo.lock needs to be updated but --locked was passed to prevent this
[INFO] the lockfile is outdated, regenerating it
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"docker" "create" "-v" "/big/crater/work/builds/worker-2/target:/opt/rustwide/target:rw,Z" "-v" "/big/crater/work/builds/worker-2/source:/opt/rustwide/workdir:ro,Z" "-v" "/big/crater/work/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/big/crater/work/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--network" "none" "rustops/crates-build-env" "/opt/rustwide/cargo-home/bin/cargo" "+1.38.0" "build" "--frozen"`
[INFO] [stdout] 21f8643f0de066c1365bcd2227d1b1aa3836447d1c60877d882cd7695853e058
[INFO] running `"docker" "start" "-a" "21f8643f0de066c1365bcd2227d1b1aa3836447d1c60877d882cd7695853e058"`
[INFO] [stderr]    Compiling extern_attrib v0.2.0 (/opt/rustwide/workdir)
[INFO] [stderr] warning: unused doc comment
[INFO] [stderr]   --> src/lib.rs:35:7
[INFO] [stderr]    |
[INFO] [stderr] 35 |       { //! This scope drops abi_opt after mutation.
[INFO] [stderr]    |  _____- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 36 | |         let abi_opt = match item.node {
[INFO] [stderr] 37 | |             ItemKind::Fn(_, _, _, ref mut opt, _, _) => opt,
[INFO] [stderr] 38 | |             _ => return input
[INFO] [stderr] 39 | |         };
[INFO] [stderr] 40 | |         modify_abi(abi_opt);
[INFO] [stderr] 41 | |     }
[INFO] [stderr]    | |_____- rustdoc does not generate documentation for expressions
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_doc_comments)]` on by default
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stderr]   --> src/lib.rs:13:1
[INFO] [stderr]    |
[INFO] [stderr] 13 | #![feature(proc_macro)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0554`.
[INFO] [stderr] error: Could not compile `extern_attrib`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "21f8643f0de066c1365bcd2227d1b1aa3836447d1c60877d882cd7695853e058"`
[INFO] running `"docker" "rm" "-f" "21f8643f0de066c1365bcd2227d1b1aa3836447d1c60877d882cd7695853e058"`
[INFO] [stdout] 21f8643f0de066c1365bcd2227d1b1aa3836447d1c60877d882cd7695853e058