[INFO] fetching crate flex-dns 1.0.1...
[INFO] testing flex-dns-1.0.1 against 1.90.0 for beta-1.91-3
[INFO] extracting crate flex-dns 1.0.1 into /workspace/builds/worker-3-tc1/source
[INFO] started tweaking crates.io crate flex-dns 1.0.1
[INFO] finished tweaking crates.io crate flex-dns 1.0.1
[INFO] tweaked toml for crates.io crate flex-dns 1.0.1 written to /workspace/builds/worker-3-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate flex-dns 1.0.1 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]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 7 packages to latest compatible versions
[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 simple-dns v0.11.0
[INFO] [stderr]   Downloaded heapless v0.9.1
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-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] 30ef031f18de99830f229cb446c6213ffd8cea0ac1d6d0d7d0d2cb7f77ffb969
[INFO] running `Command { std: "docker" "start" "-a" "30ef031f18de99830f229cb446c6213ffd8cea0ac1d6d0d7d0d2cb7f77ffb969", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "30ef031f18de99830f229cb446c6213ffd8cea0ac1d6d0d7d0d2cb7f77ffb969", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "30ef031f18de99830f229cb446c6213ffd8cea0ac1d6d0d7d0d2cb7f77ffb969", kill_on_drop: false }`
[INFO] [stdout] 30ef031f18de99830f229cb446c6213ffd8cea0ac1d6d0d7d0d2cb7f77ffb969
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-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] 2d763e0baf373fc59fdeb638e8662ae4a7069f39059a6795acea5c79d8833d32
[INFO] running `Command { std: "docker" "start" "-a" "2d763e0baf373fc59fdeb638e8662ae4a7069f39059a6795acea5c79d8833d32", kill_on_drop: false }`
[INFO] [stderr]    Compiling heapless v0.9.1
[INFO] [stderr]    Compiling flex-dns v1.0.1 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(generic_const_exprs)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
[INFO] [stdout]  --> src/lib.rs:2:12
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(generic_const_exprs)]
[INFO] [stdout]   |            ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: see issue #76560 <https://github.com/rust-lang/rust/issues/76560> for more information
[INFO] [stdout]   = note: `#[warn(incomplete_features)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `flex-dns` (lib) due to 1 previous error; 1 warning emitted
[INFO] running `Command { std: "docker" "inspect" "2d763e0baf373fc59fdeb638e8662ae4a7069f39059a6795acea5c79d8833d32", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2d763e0baf373fc59fdeb638e8662ae4a7069f39059a6795acea5c79d8833d32", kill_on_drop: false }`
[INFO] [stdout] 2d763e0baf373fc59fdeb638e8662ae4a7069f39059a6795acea5c79d8833d32