[INFO] crate microamp 0.1.0-alpha.5 is already in cache
[INFO] testing microamp-0.1.0-alpha.5 against 1.45.2 for beta-1.46-1
[INFO] extracting crate microamp 0.1.0-alpha.5 into /workspace/builds/worker-3/source
[INFO] validating manifest of crates.io crate microamp 0.1.0-alpha.5 on toolchain 1.45.2
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.45.2" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate microamp 0.1.0-alpha.5
[INFO] finished tweaking crates.io crate microamp 0.1.0-alpha.5
[INFO] tweaked toml for crates.io crate microamp 0.1.0-alpha.5 written to /workspace/builds/worker-3/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.45.2" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.45.2" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+1.45.2" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 4a476ea0365a80ec907c3dbc1f1146e7ba054109b29e88125e3f40b8d975139a
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "4a476ea0365a80ec907c3dbc1f1146e7ba054109b29e88125e3f40b8d975139a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "4a476ea0365a80ec907c3dbc1f1146e7ba054109b29e88125e3f40b8d975139a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "4a476ea0365a80ec907c3dbc1f1146e7ba054109b29e88125e3f40b8d975139a", kill_on_drop: false }`
[INFO] [stdout] 4a476ea0365a80ec907c3dbc1f1146e7ba054109b29e88125e3f40b8d975139a
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "MAP_USER_ID=0" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--network" "none" "rustops/crates-build-env@sha256:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+1.45.2" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] d64be58cd3cc8290d3ea299ab34380b3cd279f55529656ed9cca8c95f526881c
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "d64be58cd3cc8290d3ea299ab34380b3cd279f55529656ed9cca8c95f526881c", kill_on_drop: false }`
[INFO] [stderr]    Compiling microamp-macros v0.1.0-alpha.5
[INFO] [stderr]    Compiling microamp v0.1.0-alpha.5 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:4:1
[INFO] [stdout]   |
[INFO] [stdout] 4 | #![feature(external_doc)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:6:1
[INFO] [stdout]   |
[INFO] [stdout] 6 | #![feature(optin_builtin_traits)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:7:1
[INFO] [stdout]   |
[INFO] [stdout] 7 | #![feature(negative_impls)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 3 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `microamp`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "d64be58cd3cc8290d3ea299ab34380b3cd279f55529656ed9cca8c95f526881c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d64be58cd3cc8290d3ea299ab34380b3cd279f55529656ed9cca8c95f526881c", kill_on_drop: false }`
[INFO] [stdout] d64be58cd3cc8290d3ea299ab34380b3cd279f55529656ed9cca8c95f526881c