[INFO] cloning repository https://github.com/tolu0x/rustlings
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/tolu0x/rustlings" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ftolu0x%2Frustlings", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ftolu0x%2Frustlings'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 3b158ae986bc1a8d3065e7068b3c746deba43be9
[INFO] checking tolu0x/rustlings against master#64b185eddaa1d7ddf5e0c024be23b9cbba6c1722 for pr-143929
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ftolu0x%2Frustlings" "/workspace/builds/worker-0-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-0-tc1/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/tolu0x/rustlings
[INFO] finished tweaking git repo https://github.com/tolu0x/rustlings
[INFO] tweaked toml for git repo https://github.com/tolu0x/rustlings written to /workspace/builds/worker-0-tc1/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/tolu0x/rustlings on toolchain 64b185eddaa1d7ddf5e0c024be23b9cbba6c1722
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+64b185eddaa1d7ddf5e0c024be23b9cbba6c1722" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/tolu0x/rustlings 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" "+64b185eddaa1d7ddf5e0c024be23b9cbba6c1722" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-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@sha256:90999bfc7ae267e83380e433d8e61a7c072ca6729e92edbae886d3423b3a6f4c" "/opt/rustwide/cargo-home/bin/cargo" "+64b185eddaa1d7ddf5e0c024be23b9cbba6c1722" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 497432147af52e3c41d2654d697c4c855778fb572151c0ac42a1f39f4b4f441e
[INFO] running `Command { std: "docker" "start" "-a" "497432147af52e3c41d2654d697c4c855778fb572151c0ac42a1f39f4b4f441e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "497432147af52e3c41d2654d697c4c855778fb572151c0ac42a1f39f4b4f441e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "497432147af52e3c41d2654d697c4c855778fb572151c0ac42a1f39f4b4f441e", kill_on_drop: false }`
[INFO] [stdout] 497432147af52e3c41d2654d697c4c855778fb572151c0ac42a1f39f4b4f441e
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-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@sha256:90999bfc7ae267e83380e433d8e61a7c072ca6729e92edbae886d3423b3a6f4c" "/opt/rustwide/cargo-home/bin/cargo" "+64b185eddaa1d7ddf5e0c024be23b9cbba6c1722" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 3192088e89d9fe6e841aa54b7338295b69e1dd4e7b0a8a9819d68907fcc3a247
[INFO] running `Command { std: "docker" "start" "-a" "3192088e89d9fe6e841aa54b7338295b69e1dd4e7b0a8a9819d68907fcc3a247", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.140
[INFO] [stderr]    Compiling proc-macro2 v1.0.53
[INFO] [stderr]    Compiling unicode-ident v1.0.8
[INFO] [stderr]    Compiling autocfg v1.1.0
[INFO] [stderr]    Compiling quote v1.0.26
[INFO] [stderr]    Compiling serde_derive v1.0.158
[INFO] [stderr]    Compiling serde v1.0.158
[INFO] [stderr]     Checking memchr v2.6.3
[INFO] [stderr]     Checking cfg-if v1.0.0
[INFO] [stderr]     Checking anstyle v1.0.3
[INFO] [stderr]    Compiling log v0.4.17
[INFO] [stderr]     Checking utf8parse v0.2.1
[INFO] [stderr]     Checking cfg-if v0.1.10
[INFO] [stderr]     Checking hashbrown v0.14.0
[INFO] [stderr]     Checking anstyle-parse v0.2.1
[INFO] [stderr]     Checking anstyle-query v1.0.0
[INFO] [stderr]    Compiling slab v0.4.8
[INFO] [stderr]    Compiling num-traits v0.2.15
[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] [stderr]     Checking aho-corasick v0.7.20
[INFO] [stderr]     Checking regex-syntax v0.6.29
[INFO] [stderr]    Compiling portable-atomic v1.4.3
[INFO] [stderr]     Checking colorchoice v1.0.0
[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" "3192088e89d9fe6e841aa54b7338295b69e1dd4e7b0a8a9819d68907fcc3a247", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "3192088e89d9fe6e841aa54b7338295b69e1dd4e7b0a8a9819d68907fcc3a247", kill_on_drop: false }`
[INFO] [stdout] 3192088e89d9fe6e841aa54b7338295b69e1dd4e7b0a8a9819d68907fcc3a247