[INFO] fetching crate mantle-macros 0.2.1...
[INFO] testing mantle-macros-0.2.1 against 1.90.0 for beta-1.91-3
[INFO] extracting crate mantle-macros 0.2.1 into /workspace/builds/worker-2-tc1/source
[INFO] started tweaking crates.io crate mantle-macros 0.2.1
[INFO] finished tweaking crates.io crate mantle-macros 0.2.1
[INFO] tweaked toml for crates.io crate mantle-macros 0.2.1 written to /workspace/builds/worker-2-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate mantle-macros 0.2.1 on toolchain 1.90.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 9 packages to latest compatible versions
[INFO] [stderr]       Adding proc-macro2 v0.4.30 (available: v1.0.101)
[INFO] [stderr]       Adding proc-quote v0.2.2 (available: v0.4.0)
[INFO] [stderr]       Adding syn v0.15.44 (available: v2.0.106)
[INFO] [stderr]       Adding tiny-keccak v1.5.0 (available: v2.0.2)
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded tiny-keccak v1.5.0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+1.90.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 1f96a136e35aeb1b9a827b955a3774ba63b2502304e9e8f913bd9af5a45db194
[INFO] running `Command { std: "docker" "start" "-a" "1f96a136e35aeb1b9a827b955a3774ba63b2502304e9e8f913bd9af5a45db194", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "1f96a136e35aeb1b9a827b955a3774ba63b2502304e9e8f913bd9af5a45db194", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1f96a136e35aeb1b9a827b955a3774ba63b2502304e9e8f913bd9af5a45db194", kill_on_drop: false }`
[INFO] [stdout] 1f96a136e35aeb1b9a827b955a3774ba63b2502304e9e8f913bd9af5a45db194
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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=warn" "-e" "RUSTDOCFLAGS=--cap-lints=warn" "-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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+1.90.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] b824e9ae4c8bfe5bd41a334aad53b556be47300348544ae931efa109d6f4ddeb
[INFO] running `Command { std: "docker" "start" "-a" "b824e9ae4c8bfe5bd41a334aad53b556be47300348544ae931efa109d6f4ddeb", kill_on_drop: false }`
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling crunchy v0.2.4
[INFO] [stderr]    Compiling tiny-keccak v1.5.0
[INFO] [stderr]    Compiling proc-quote v0.2.2
[INFO] [stderr]    Compiling mantle-macros v0.2.1 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(proc_macro_diagnostic, type_ascription)]
[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 `mantle-macros` (lib) due to 1 previous error
[INFO] running `Command { std: "docker" "inspect" "b824e9ae4c8bfe5bd41a334aad53b556be47300348544ae931efa109d6f4ddeb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b824e9ae4c8bfe5bd41a334aad53b556be47300348544ae931efa109d6f4ddeb", kill_on_drop: false }`
[INFO] [stdout] b824e9ae4c8bfe5bd41a334aad53b556be47300348544ae931efa109d6f4ddeb