[INFO] fetching crate rug-polynomial 0.2.5...
[INFO] checking rug-polynomial-0.2.5 against master#f609b7e0586f81fefb3523e3e17adf779ac416be for pr-129466-2
[INFO] extracting crate rug-polynomial 0.2.5 into /workspace/builds/worker-4-tc1/source
[INFO] validating manifest of crates.io crate rug-polynomial 0.2.5 on toolchain f609b7e0586f81fefb3523e3e17adf779ac416be
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+f609b7e0586f81fefb3523e3e17adf779ac416be" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate rug-polynomial 0.2.5
[INFO] finished tweaking crates.io crate rug-polynomial 0.2.5
[INFO] tweaked toml for crates.io crate rug-polynomial 0.2.5 written to /workspace/builds/worker-4-tc1/source/Cargo.toml
[INFO] crate crates.io crate rug-polynomial 0.2.5 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" "+f609b7e0586f81fefb3523e3e17adf779ac416be" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded serde v1.0.155
[INFO] [stderr]   Downloaded serde_derive v1.0.155
[INFO] [stderr]   Downloaded flint-sys v0.7.3
[INFO] [stderr]   Downloaded rug-fft v0.1.2
[INFO] [stderr]   Downloaded rug v1.18.0
[INFO] [stderr]   Downloaded gmp-mpfr-sys v1.4.13
[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:ceb6ea022f8a89cebbe621bb4987e73a935bd40dfbb726f832cfff4742a5b95a" "/opt/rustwide/cargo-home/bin/cargo" "+f609b7e0586f81fefb3523e3e17adf779ac416be" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 5a3c6ace7ef310d75889c14c4fdd6e401c139cc8c73ddd1e34a4875e12be28d8
[INFO] running `Command { std: "docker" "start" "-a" "5a3c6ace7ef310d75889c14c4fdd6e401c139cc8c73ddd1e34a4875e12be28d8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "5a3c6ace7ef310d75889c14c4fdd6e401c139cc8c73ddd1e34a4875e12be28d8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5a3c6ace7ef310d75889c14c4fdd6e401c139cc8c73ddd1e34a4875e12be28d8", kill_on_drop: false }`
[INFO] [stdout] 5a3c6ace7ef310d75889c14c4fdd6e401c139cc8c73ddd1e34a4875e12be28d8
[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:ceb6ea022f8a89cebbe621bb4987e73a935bd40dfbb726f832cfff4742a5b95a" "/opt/rustwide/cargo-home/bin/cargo" "+f609b7e0586f81fefb3523e3e17adf779ac416be" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] b679045474406d6da382604b76873c0ac01a06c1e8591268917ce039ba45fe82
[INFO] running `Command { std: "docker" "start" "-a" "b679045474406d6da382604b76873c0ac01a06c1e8591268917ce039ba45fe82", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.140
[INFO] [stderr]    Compiling proc-macro2 v1.0.52
[INFO] [stderr]    Compiling quote v1.0.26
[INFO] [stderr]    Compiling gmp-mpfr-sys v1.4.13
[INFO] [stderr]    Compiling syn v1.0.109
[INFO] [stderr]    Compiling memchr v2.5.0
[INFO] [stderr]    Compiling serde_derive v1.0.155
[INFO] [stderr]    Compiling getrandom v0.1.16
[INFO] [stderr]    Compiling az v1.2.1
[INFO] [stderr]    Compiling serde v1.0.155
[INFO] [stderr]    Compiling rug v1.18.0
[INFO] [stderr]    Compiling log v0.4.17
[INFO] [stdout] error[E0635]: unknown feature `proc_macro_span_shrink`
[INFO] [stdout]   --> /opt/rustwide/cargo-home/registry/src/index.crates.io-6f17d22bba15001f/proc-macro2-1.0.52/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 regex-syntax v0.6.28
[INFO] [stderr]     Checking ppv-lite86 v0.2.17
[INFO] [stderr]    Compiling flint-sys v0.7.3
[INFO] [stderr]     Checking aho-corasick v0.7.20
[INFO] [stdout] error: aborting due to 1 previous error
[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 2 previous errors
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] running `Command { std: "docker" "inspect" "b679045474406d6da382604b76873c0ac01a06c1e8591268917ce039ba45fe82", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b679045474406d6da382604b76873c0ac01a06c1e8591268917ce039ba45fe82", kill_on_drop: false }`
[INFO] [stdout] b679045474406d6da382604b76873c0ac01a06c1e8591268917ce039ba45fe82