[INFO] cloning repository https://github.com/ula-lang/ula
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/ula-lang/ula" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fula-lang%2Fula", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fula-lang%2Fula'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 13578eead1253ff798653507cf45fb39fbe17743
[INFO] checking ula-lang/ula against 1.95.0 for pr-155915
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fula-lang%2Fula" "/workspace/builds/worker-6-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6-tc1/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/ula-lang/ula
[INFO] finished tweaking git repo https://github.com/ula-lang/ula
[INFO] tweaked toml for git repo https://github.com/ula-lang/ula written to /workspace/builds/worker-6-tc1/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/ula-lang/ula on toolchain 1.95.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.95.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/ula-lang/ula 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" "+1.95.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded lalr v0.0.2
[INFO] [stderr]   Downloaded plex v0.2.3
[INFO] [stderr]   Downloaded quote v0.6.8
[INFO] [stderr]   Downloaded redfa v0.0.2
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+1.95.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 79dd1ba56900aa72e9257ea055781bd4e3cd1c09c3d7023b872c2074bd6ea041
[INFO] running `Command { std: "docker" "start" "-a" "79dd1ba56900aa72e9257ea055781bd4e3cd1c09c3d7023b872c2074bd6ea041", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "79dd1ba56900aa72e9257ea055781bd4e3cd1c09c3d7023b872c2074bd6ea041", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "79dd1ba56900aa72e9257ea055781bd4e3cd1c09c3d7023b872c2074bd6ea041", kill_on_drop: false }`
[INFO] [stdout] 79dd1ba56900aa72e9257ea055781bd4e3cd1c09c3d7023b872c2074bd6ea041
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+1.95.0" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 8687b7dc52b3615b2d016eb0887bb75d4780a34942130b811838dd2f4ff99a31
[INFO] running `Command { std: "docker" "start" "-a" "8687b7dc52b3615b2d016eb0887bb75d4780a34942130b811838dd2f4ff99a31", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v0.4.20
[INFO] [stderr]    Compiling libc v0.2.65
[INFO] [stderr]    Compiling getrandom v0.1.13
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling bit-vec v0.4.4
[INFO] [stderr]    Compiling vec_map v0.6.0
[INFO] [stderr]    Compiling lalr v0.0.2
[INFO] [stderr]     Checking c2-chacha v0.2.3
[INFO] [stderr]    Compiling bit-set v0.4.0
[INFO] [stderr]    Compiling redfa v0.0.2
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking rand_chacha v0.2.1
[INFO] [stderr]    Compiling quote v0.6.8
[INFO] [stderr]     Checking rand v0.7.2
[INFO] [stderr]    Compiling syn v0.14.9
[INFO] [stderr]    Compiling derivative v1.0.3
[INFO] [stderr]    Compiling plex v0.2.3
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/plex-0.2.3/src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(proc_macro_diagnostic)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `plex` (lib) due to 1 previous error
[INFO] running `Command { std: "docker" "inspect" "8687b7dc52b3615b2d016eb0887bb75d4780a34942130b811838dd2f4ff99a31", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8687b7dc52b3615b2d016eb0887bb75d4780a34942130b811838dd2f4ff99a31", kill_on_drop: false }`
[INFO] [stdout] 8687b7dc52b3615b2d016eb0887bb75d4780a34942130b811838dd2f4ff99a31