[INFO] cloning repository https://github.com/anderejd/extern_attrib
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/anderejd/extern_attrib" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fanderejd%2Fextern_attrib", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fanderejd%2Fextern_attrib'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] a70c0caf5ddb993cde6e65d89b125f168e1d5dcc
[INFO] testing anderejd/extern_attrib against beta-2021-09-08 for beta-1.56-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fanderejd%2Fextern_attrib" "/workspace/builds/worker-12/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-12/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/anderejd/extern_attrib on toolchain beta-2021-09-08
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-09-08" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[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 /workspace/builds/worker-12/source/Cargo.toml
[INFO] crate git repo https://github.com/anderejd/extern_attrib already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-09-08" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2021-09-08" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] f8e71548839fe40098cb8d711ebb5d1eed0156a3fe5b3088774c85fb7677bff9
[INFO] running `Command { std: "docker" "start" "-a" "f8e71548839fe40098cb8d711ebb5d1eed0156a3fe5b3088774c85fb7677bff9", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "f8e71548839fe40098cb8d711ebb5d1eed0156a3fe5b3088774c85fb7677bff9", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f8e71548839fe40098cb8d711ebb5d1eed0156a3fe5b3088774c85fb7677bff9", kill_on_drop: false }`
[INFO] [stdout] f8e71548839fe40098cb8d711ebb5d1eed0156a3fe5b3088774c85fb7677bff9
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-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" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2021-09-08" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 14c6cf4c66adda26ad9f458469267e9891a31fc7187537e28de636a708d041d6
[INFO] running `Command { std: "docker" "start" "-a" "14c6cf4c66adda26ad9f458469267e9891a31fc7187537e28de636a708d041d6", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling syn v0.11.11
[INFO] [stderr]    Compiling extern_attrib v0.2.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]   --> src/lib.rs:13:1
[INFO] [stdout]    |
[INFO] [stdout] 13 | #![feature(proc_macro)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^^^^^^ help: remove the attribute
[INFO] [stdout]    |
[INFO] [stdout]    = help: the feature `proc_macro` has been stable since 1.29.0 and no longer requires an attribute to enable
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused doc comment
[INFO] [stdout]   --> src/lib.rs:35:7
[INFO] [stdout]    |
[INFO] [stdout] 35 |       { //! This scope drops abi_opt after mutation.
[INFO] [stdout]    |  _____- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 36 | |         let abi_opt = match item.node {
[INFO] [stdout] 37 | |             ItemKind::Fn(_, _, _, ref mut opt, _, _) => opt,
[INFO] [stdout] 38 | |             _ => return input
[INFO] [stdout] 39 | |         };
[INFO] [stdout] 40 | |         modify_abi(abi_opt);
[INFO] [stdout] 41 | |     }
[INFO] [stdout]    | |_____- rustdoc does not generate documentation for expressions
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_doc_comments)]` on by default
[INFO] [stdout]    = help: use `//` for a plain comment
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error; 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `extern_attrib` due to 2 previous errors; 1 warning emitted
[INFO] running `Command { std: "docker" "inspect" "14c6cf4c66adda26ad9f458469267e9891a31fc7187537e28de636a708d041d6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "14c6cf4c66adda26ad9f458469267e9891a31fc7187537e28de636a708d041d6", kill_on_drop: false }`
[INFO] [stdout] 14c6cf4c66adda26ad9f458469267e9891a31fc7187537e28de636a708d041d6