[INFO] cloning repository https://github.com/gelove/rustlings-answer
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/gelove/rustlings-answer" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgelove%2Frustlings-answer", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgelove%2Frustlings-answer'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 4f12330c9a08482cb3621e61b9016660cdc31844
[INFO] checking gelove/rustlings-answer against master#cb06d12710575a0d7ff71d6fe108f3bcff4f9195 for pr-128425-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgelove%2Frustlings-answer" "/workspace/builds/worker-4-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/gelove/rustlings-answer on toolchain cb06d12710575a0d7ff71d6fe108f3bcff4f9195
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+cb06d12710575a0d7ff71d6fe108f3bcff4f9195" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/gelove/rustlings-answer
[INFO] finished tweaking git repo https://github.com/gelove/rustlings-answer
[INFO] tweaked toml for git repo https://github.com/gelove/rustlings-answer written to /workspace/builds/worker-4-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/gelove/rustlings-answer already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+cb06d12710575a0d7ff71d6fe108f3bcff4f9195" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/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@sha256:3959728d45483eb673ba100a951a6b9f5012970368db2a9e08e0ac9b67c8a5ad" "/opt/rustwide/cargo-home/bin/cargo" "+cb06d12710575a0d7ff71d6fe108f3bcff4f9195" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 70b809a26f1dffc56777bc17b96e63b3de580334485453c848cff869d764d5dc
[INFO] running `Command { std: "docker" "start" "-a" "70b809a26f1dffc56777bc17b96e63b3de580334485453c848cff869d764d5dc", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "70b809a26f1dffc56777bc17b96e63b3de580334485453c848cff869d764d5dc", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "70b809a26f1dffc56777bc17b96e63b3de580334485453c848cff869d764d5dc", kill_on_drop: false }`
[INFO] [stdout] 70b809a26f1dffc56777bc17b96e63b3de580334485453c848cff869d764d5dc
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/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=forbid" "-e" "RUSTDOCFLAGS=--cap-lints=forbid" "-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@sha256:3959728d45483eb673ba100a951a6b9f5012970368db2a9e08e0ac9b67c8a5ad" "/opt/rustwide/cargo-home/bin/cargo" "+cb06d12710575a0d7ff71d6fe108f3bcff4f9195" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] ad718db8a7310db7d35ab10b5b82405425517f4c87248219959232ecb8155f49
[INFO] running `Command { std: "docker" "start" "-a" "ad718db8a7310db7d35ab10b5b82405425517f4c87248219959232ecb8155f49", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.53
[INFO] [stderr]    Compiling libc v0.2.140
[INFO] [stderr]    Compiling memchr v2.5.0
[INFO] [stderr]    Compiling serde_derive v1.0.158
[INFO] [stderr]    Compiling serde v1.0.158
[INFO] [stderr]    Compiling syn v1.0.109
[INFO] [stderr]    Compiling serde_json v1.0.94
[INFO] [stderr]     Checking regex-syntax v0.6.29
[INFO] [stderr]     Checking cfg-if v0.1.10
[INFO] [stderr]     Checking ryu v1.0.13
[INFO] [stderr]    Compiling slab v0.4.8
[INFO] [stderr]    Compiling num-traits v0.2.15
[INFO] [stderr]     Checking itoa v1.0.6
[INFO] [stderr]    Compiling escargot v0.4.0
[INFO] [stderr]     Checking same-file v1.0.6
[INFO] [stderr]     Checking predicates-core v1.0.6
[INFO] [stderr]     Checking unicode-width v0.1.10
[INFO] [stderr]    Compiling argh_shared v0.1.10
[INFO] [stderr]     Checking lazycell v1.3.0
[INFO] [stderr]     Checking walkdir v2.3.3
[INFO] [stderr]     Checking difference v2.0.0
[INFO] [stderr]     Checking normalize-line-endings v0.3.0
[INFO] [stderr]     Checking number_prefix v0.4.0
[INFO] [stderr]     Checking termtree v0.4.1
[INFO] [stderr]     Checking home v0.5.4
[INFO] [stderr]     Checking glob v0.3.1
[INFO] [stderr]     Checking predicates-tree v1.0.9
[INFO] [stdout] error[E0635]: unknown feature `proc_macro_span_shrink`
[INFO] [stdout]   --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/proc-macro2-1.0.53/src/lib.rs:92:30
[INFO] [stdout]    |
[INFO] [stdout] 92 |     feature(proc_macro_span, proc_macro_span_shrink)
[INFO] [stdout]    |                              ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0635`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `proc-macro2` (lib) due to 1 previous error
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] running `Command { std: "docker" "inspect" "ad718db8a7310db7d35ab10b5b82405425517f4c87248219959232ecb8155f49", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ad718db8a7310db7d35ab10b5b82405425517f4c87248219959232ecb8155f49", kill_on_drop: false }`
[INFO] [stdout] ad718db8a7310db7d35ab10b5b82405425517f4c87248219959232ecb8155f49