[INFO] crate rcmark 0.1.0 is already in cache
[INFO] extracting crate rcmark 0.1.0 into work/ex/beta-1.38-1/sources/1.37.0/reg/rcmark/0.1.0
[INFO] extracting crate rcmark 0.1.0 into work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/rcmark/0.1.0
[INFO] validating manifest of rcmark-0.1.0 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 rcmark-0.1.0 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 rcmark-0.1.0
[INFO] removed path dependency libcmark-sys from rcmark-0.1.0
[INFO] finished frobbing rcmark-0.1.0
[INFO] frobbed toml for rcmark-0.1.0 written to work/ex/beta-1.38-1/sources/1.37.0/reg/rcmark/0.1.0/Cargo.toml
[INFO] started frobbing rcmark-0.1.0
[INFO] removed path dependency libcmark-sys from rcmark-0.1.0
[INFO] finished frobbing rcmark-0.1.0
[INFO] frobbed toml for rcmark-0.1.0 written to work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/rcmark/0.1.0/Cargo.toml
[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] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing rcmark-0.1.0 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-6/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/reg/rcmark/0.1.0:/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" "+1.37.0" "build" "--frozen"`
[INFO] [stdout] 8dee8b1fc5a6fe137759f747d21755ad49a52b2e62ac3ab41cfea70432b2917d
[INFO] running `"docker" "start" "-a" "8dee8b1fc5a6fe137759f747d21755ad49a52b2e62ac3ab41cfea70432b2917d"`
[INFO] [stderr]    Compiling bitflags v0.1.1
[INFO] [stderr]    Compiling libcmark-sys v0.1.0
[INFO] [stderr]    Compiling rcmark v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] warning: unused doc comment
[INFO] [stderr]    --> src/lib.rs:264:1
[INFO] [stderr]     |
[INFO] [stderr] 264 |   /// Options for parsing and rendering a node tree.
[INFO] [stderr]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 265 | / bitflags! {
[INFO] [stderr] 266 | |     flags CmarkOptions: i32 {
[INFO] [stderr] 267 | |         #[doc="Default writer options"]
[INFO] [stderr] 268 | |         const DEFAULT = raw::CMARK_OPT_DEFAULT as i32,
[INFO] [stderr] ...   |
[INFO] [stderr] 277 | |     }
[INFO] [stderr] 278 | | }
[INFO] [stderr]     | |_- rustdoc does not generate documentation for macro expansions
[INFO] [stderr]     |
[INFO] [stderr]     = note: #[warn(unused_doc_comments)] on by default
[INFO] [stderr]     = help: to document an item produced by a macro, the macro must produce the documentation as part of its expansion
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]   --> src/lib.rs:73:1
[INFO] [stderr]    |
[INFO] [stderr] 73 | #![feature(concat_idents)]
[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 `rcmark`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "8dee8b1fc5a6fe137759f747d21755ad49a52b2e62ac3ab41cfea70432b2917d"`
[INFO] running `"docker" "rm" "-f" "8dee8b1fc5a6fe137759f747d21755ad49a52b2e62ac3ab41cfea70432b2917d"`
[INFO] [stdout] 8dee8b1fc5a6fe137759f747d21755ad49a52b2e62ac3ab41cfea70432b2917d