[INFO] fetching crate alloc-cortex-m 0.4.4...
[INFO] checking alloc-cortex-m-0.4.4 against try#998b6603a58e47f42ccce7a67943234e96b6839e for pr-143170
[INFO] extracting crate alloc-cortex-m 0.4.4 into /workspace/builds/worker-0-tc2/source
[INFO] started tweaking crates.io crate alloc-cortex-m 0.4.4
[INFO] finished tweaking crates.io crate alloc-cortex-m 0.4.4
[INFO] tweaked toml for crates.io crate alloc-cortex-m 0.4.4 written to /workspace/builds/worker-0-tc2/source/Cargo.toml
[INFO] validating manifest of crates.io crate alloc-cortex-m 0.4.4 on toolchain 998b6603a58e47f42ccce7a67943234e96b6839e
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+998b6603a58e47f42ccce7a67943234e96b6839e" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate crates.io crate alloc-cortex-m 0.4.4 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" "+998b6603a58e47f42ccce7a67943234e96b6839e" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/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" "+998b6603a58e47f42ccce7a67943234e96b6839e" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] d47bf0ca3a4bfc65dc577847ac0b3322662e01f04ea950e25dff0c7739b95295
[INFO] running `Command { std: "docker" "start" "-a" "d47bf0ca3a4bfc65dc577847ac0b3322662e01f04ea950e25dff0c7739b95295", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "d47bf0ca3a4bfc65dc577847ac0b3322662e01f04ea950e25dff0c7739b95295", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d47bf0ca3a4bfc65dc577847ac0b3322662e01f04ea950e25dff0c7739b95295", kill_on_drop: false }`
[INFO] [stdout] d47bf0ca3a4bfc65dc577847ac0b3322662e01f04ea950e25dff0c7739b95295
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/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" "+998b6603a58e47f42ccce7a67943234e96b6839e" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 31718c1ca5a8e9c4be1b74089c7b8c113eefe931ee0e3fc9ecbad87a960ad08f
[INFO] running `Command { std: "docker" "start" "-a" "31718c1ca5a8e9c4be1b74089c7b8c113eefe931ee0e3fc9ecbad87a960ad08f", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.49
[INFO] [stderr]    Compiling quote v1.0.23
[INFO] [stderr]    Compiling unicode-ident v1.0.6
[INFO] [stderr]    Compiling bare-metal v0.2.5
[INFO] [stderr]    Compiling syn v1.0.107
[INFO] [stderr]     Checking nb v1.0.0
[INFO] [stderr]    Compiling cortex-m v0.7.6
[INFO] [stderr]     Checking vcell v0.1.3
[INFO] [stderr]     Checking nb v0.1.3
[INFO] [stderr]     Checking void v1.0.2
[INFO] [stderr]     Checking volatile-register v0.2.1
[INFO] [stderr]    Compiling cortex-m-rt v0.6.15
[INFO] [stderr]     Checking bitfield v0.13.2
[INFO] [stderr]     Checking embedded-hal v0.2.7
[INFO] [stderr]     Checking linked_list_allocator v0.10.4
[INFO] [stderr]     Checking r0 v0.2.2
[INFO] [stdout] error[E0635]: unknown feature `proc_macro_span_shrink`
[INFO] [stdout]   --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/proc-macro2-1.0.49/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 alloc-cortex-m v0.4.4 (/opt/rustwide/workdir)
[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] running `Command { std: "docker" "inspect" "31718c1ca5a8e9c4be1b74089c7b8c113eefe931ee0e3fc9ecbad87a960ad08f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "31718c1ca5a8e9c4be1b74089c7b8c113eefe931ee0e3fc9ecbad87a960ad08f", kill_on_drop: false }`
[INFO] [stdout] 31718c1ca5a8e9c4be1b74089c7b8c113eefe931ee0e3fc9ecbad87a960ad08f