[INFO] cloning repository https://github.com/cortesem/microbit-playground
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/cortesem/microbit-playground" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fcortesem%2Fmicrobit-playground", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fcortesem%2Fmicrobit-playground'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 4778d894767b25d0a811a118ff5367bd6730e9fd
[INFO] testing cortesem/microbit-playground against beta-2026-03-05 for beta-1.95-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fcortesem%2Fmicrobit-playground" "/workspace/builds/worker-0-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-0-tc2/source'...
[INFO] [stderr] done.
[INFO] removed /workspace/builds/worker-0-tc2/source/.cargo/config.toml
[INFO] started tweaking git repo https://github.com/cortesem/microbit-playground
[INFO] finished tweaking git repo https://github.com/cortesem/microbit-playground
[INFO] tweaked toml for git repo https://github.com/cortesem/microbit-playground written to /workspace/builds/worker-0-tc2/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/cortesem/microbit-playground on toolchain beta-2026-03-05
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2026-03-05" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/cortesem/microbit-playground 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" "+beta-2026-03-05" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded rtt-target v0.6.1
[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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2026-03-05" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 89530ff666545cae1dae53884e0c80d9bb8784853913363f8acc52e4e706e027
[INFO] running `Command { std: "docker" "start" "-a" "89530ff666545cae1dae53884e0c80d9bb8784853913363f8acc52e4e706e027", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "89530ff666545cae1dae53884e0c80d9bb8784853913363f8acc52e4e706e027", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "89530ff666545cae1dae53884e0c80d9bb8784853913363f8acc52e4e706e027", kill_on_drop: false }`
[INFO] [stdout] 89530ff666545cae1dae53884e0c80d9bb8784853913363f8acc52e4e706e027
[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=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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2026-03-05" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] a5360f63cf8dfe38b524287181a3cf6be4d05998dea773404d81a5c80b84fc39
[INFO] running `Command { std: "docker" "start" "-a" "a5360f63cf8dfe38b524287181a3cf6be4d05998dea773404d81a5c80b84fc39", kill_on_drop: false }`
[INFO] [stderr]    Compiling semver-parser v0.7.0
[INFO] [stderr]    Compiling nb v1.1.0
[INFO] [stderr]    Compiling portable-atomic v1.11.0
[INFO] [stderr]    Compiling void v1.0.2
[INFO] [stderr]    Compiling vcell v0.1.3
[INFO] [stderr]    Compiling cortex-m-rt v0.7.5
[INFO] [stderr]    Compiling critical-section v1.2.0
[INFO] [stderr]    Compiling syn v2.0.101
[INFO] [stderr]    Compiling nb v0.1.3
[INFO] [stderr]    Compiling cortex-m v0.7.7
[INFO] [stderr]    Compiling volatile-register v0.2.2
[INFO] [stderr]    Compiling bitfield v0.13.2
[INFO] [stderr]    Compiling embedded-hal v0.2.7
[INFO] [stderr]    Compiling ufmt-write v0.1.0
[INFO] [stderr]    Compiling semver v0.9.0
[INFO] [stderr]    Compiling panic-halt v1.0.0
[INFO] [stderr]    Compiling rustc_version v0.2.3
[INFO] [stderr]    Compiling rtt-target v0.6.1
[INFO] [stderr]    Compiling bare-metal v0.2.5
[INFO] [stderr]    Compiling cortex-m-rt-macros v0.7.5
[INFO] [stderr]    Compiling microbit-playground v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error: unwinding panics are not supported without std
[INFO] [stdout]   |
[INFO] [stdout]   = help: using nightly cargo, use -Zbuild-std with panic="abort" to avoid unwinding
[INFO] [stdout]   = note: since the core library is usually precompiled with panic="unwind", rebuilding your crate with panic="abort" may not be enough to fix the problem
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable `x` is assigned to, but never used
[INFO] [stdout]   --> src/main.rs:10:9
[INFO] [stdout]    |
[INFO] [stdout] 10 |     let mut x: usize = 0;
[INFO] [stdout]    |         ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: consider using `_x` instead
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `x` is never read
[INFO] [stdout]   --> src/main.rs:12:9
[INFO] [stdout]    |
[INFO] [stdout] 12 |         x += 1;
[INFO] [stdout]    |         ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout]    = note: `#[warn(unused_assignments)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `microbit-playground` (bin "microbit-playground") due to 1 previous error; 2 warnings emitted
[INFO] running `Command { std: "docker" "inspect" "a5360f63cf8dfe38b524287181a3cf6be4d05998dea773404d81a5c80b84fc39", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a5360f63cf8dfe38b524287181a3cf6be4d05998dea773404d81a5c80b84fc39", kill_on_drop: false }`
[INFO] [stdout] a5360f63cf8dfe38b524287181a3cf6be4d05998dea773404d81a5c80b84fc39