[INFO] cloning repository https://github.com/KarpelesLab/chiefstaker
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/KarpelesLab/chiefstaker" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FKarpelesLab%2Fchiefstaker", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FKarpelesLab%2Fchiefstaker'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 51a66274441f7a841ca85b8c6713925dce56c4e0
[INFO] checking KarpelesLab/chiefstaker against master#4cf5f9580233c36f6bc8db76e282ba8a1c1ea491 for pr-154585
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FKarpelesLab%2Fchiefstaker" "/workspace/builds/worker-2-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-2-tc1/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/KarpelesLab/chiefstaker
[INFO] finished tweaking git repo https://github.com/KarpelesLab/chiefstaker
[INFO] tweaked toml for git repo https://github.com/KarpelesLab/chiefstaker written to /workspace/builds/worker-2-tc1/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/KarpelesLab/chiefstaker on toolchain 4cf5f9580233c36f6bc8db76e282ba8a1c1ea491
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+4cf5f9580233c36f6bc8db76e282ba8a1c1ea491" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/KarpelesLab/chiefstaker 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" "+4cf5f9580233c36f6bc8db76e282ba8a1c1ea491" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded spl-token-metadata-interface v0.5.1
[INFO] [stderr]   Downloaded foldhash v0.1.3
[INFO] [stderr]   Downloaded serde_bytes v0.11.19
[INFO] [stderr]   Downloaded spl-program-error v0.5.0
[INFO] [stderr]   Downloaded solana-rpc-client-nonce-utils v2.0.25
[INFO] [stderr]   Downloaded multimap v0.8.3
[INFO] [stderr]   Downloaded enum-ordinalize v3.1.15
[INFO] [stderr]   Downloaded task-local-extensions v0.1.4
[INFO] [stderr]   Downloaded solana-transaction-metrics-tracker v2.0.25
[INFO] [stderr]   Downloaded solana-pubsub-client v2.0.25
[INFO] [stderr]   Downloaded educe v0.4.23
[INFO] [stderr]   Downloaded chrono-humanize v0.2.3
[INFO] [stderr]   Downloaded async-mutex v1.4.1
[INFO] [stderr]   Downloaded solana-rpc-client v2.0.25
[INFO] [stderr]   Downloaded opentelemetry v0.17.0
[INFO] [stderr]   Downloaded solana_rbpf v0.8.4
[INFO] [stderr]   Downloaded solana-banks-server v2.0.25
[INFO] [stderr]   Downloaded solana-accounts-db v2.0.25
[INFO] [stderr]   Downloaded solana-program-test v2.0.25
[INFO] [stderr]   Downloaded rpassword v7.4.0
[INFO] [stderr]   Downloaded modular-bitfield-impl v0.11.2
[INFO] [stderr]   Downloaded solana-compute-budget-program v2.0.25
[INFO] [stderr]   Downloaded solana-runtime v2.0.25
[INFO] [stderr]   Downloaded spl-transfer-hook-interface v0.7.0
[INFO] [stderr]   Downloaded spl-token-confidential-transfer-proof-extraction v0.1.0
[INFO] [stderr]   Downloaded tracing-opentelemetry v0.17.4
[INFO] [stderr]   Downloaded spl-token-2022 v5.0.2
[INFO] [stderr]   Downloaded solana-sdk v2.0.25
[INFO] [stderr]   Downloaded solana-send-transaction-service v2.0.25
[INFO] [stderr]   Downloaded solana-program v2.0.25
[INFO] [stderr]   Downloaded seqlock v0.2.0
[INFO] [stderr]   Downloaded solana-rayon-threadlimit v2.0.25
[INFO] [stderr]   Downloaded spl-tlv-account-resolution v0.7.0
[INFO] [stderr]   Downloaded spl-token-2022 v4.0.0
[INFO] [stderr]   Downloaded spl-pod v0.3.1
[INFO] [stderr]   Downloaded spl-token-group-interface v0.4.2
[INFO] [stderr]   Downloaded solana-remote-wallet v2.0.25
[INFO] [stderr]   Downloaded solana-clap-utils v2.0.25
[INFO] [stderr]   Downloaded solana-net-utils v2.0.25
[INFO] [stderr]   Downloaded tarpc v0.29.0
[INFO] [stderr]   Downloaded solana-stake-program v2.0.25
[INFO] [stderr]   Downloaded symlink v0.1.0
[INFO] [stderr]   Downloaded tempfile v3.15.0
[INFO] [stderr]   Downloaded solana-bpf-loader-program v2.0.25
[INFO] [stderr]   Downloaded solana-svm v2.0.25
[INFO] [stderr]   Downloaded async-compression v0.4.37
[INFO] [stderr]   Downloaded spl-token v6.0.0
[INFO] [stderr]   Downloaded spl-transfer-hook-interface v0.8.2
[INFO] [stderr]   Downloaded solana-banks-client v2.0.25
[INFO] [stderr]   Downloaded solana-banks-interface v2.0.25
[INFO] [stderr]   Downloaded solana-quic-client v2.0.25
[INFO] [stderr]   Downloaded rtoolbox v0.0.3
[INFO] [stderr]   Downloaded mockall_derive v0.11.4
[INFO] [stderr]   Downloaded mockall v0.11.4
[INFO] [stderr]   Downloaded index_list v0.2.17
[INFO] [stderr]   Downloaded modular-bitfield v0.11.2
[INFO] [stderr]   Downloaded caps v0.5.6
[INFO] [stderr]   Downloaded solana-version v2.0.25
[INFO] [stderr]   Downloaded solana-zk-token-proof-program v2.0.25
[INFO] [stderr]   Downloaded prost-derive v0.11.9
[INFO] [stderr]   Downloaded dir-diff v0.3.3
[INFO] [stderr]   Downloaded solana-account-decoder v2.0.25
[INFO] [stderr]   Downloaded solana-vote-program v2.0.25
[INFO] [stderr]   Downloaded solana-security-txt v1.1.2
[INFO] [stderr]   Downloaded solana-zk-token-sdk v2.0.25
[INFO] [stderr]   Downloaded spl-tlv-account-resolution v0.8.1
[INFO] [stderr]   Downloaded predicates v2.1.5
[INFO] [stderr]   Downloaded solana-bucket-map v2.0.25
[INFO] [stderr]   Downloaded solana-transaction-status v2.0.25
[INFO] [stderr]   Downloaded prost-types v0.11.9
[INFO] [stderr]   Downloaded prost-build v0.11.9
[INFO] [stderr]   Downloaded solana-measure v2.0.25
[INFO] [stderr]   Downloaded solana-metrics v2.0.25
[INFO] [stderr]   Downloaded solana-vote v2.0.25
[INFO] [stderr]   Downloaded solana-program-runtime v2.0.25
[INFO] [stderr]   Downloaded spl-token-confidential-transfer-ciphertext-arithmetic v0.1.0
[INFO] [stderr]   Downloaded spl-token-confidential-transfer-proof-generation v0.1.0
[INFO] [stderr]   Downloaded spl-discriminator-syn v0.2.1
[INFO] [stderr]   Downloaded solana-streamer v2.0.25
[INFO] [stderr]   Downloaded solana-client v2.0.25
[INFO] [stderr]   Downloaded solana-connection-cache v2.0.25
[INFO] [stderr]   Downloaded reqwest-middleware v0.2.5
[INFO] [stderr]   Downloaded tarpc-plugins v0.12.0
[INFO] [stderr]   Downloaded solana-logger v2.0.25
[INFO] [stderr]   Downloaded solana-inline-spl v2.0.25
[INFO] [stderr]   Downloaded solana-perf v2.0.25
[INFO] [stderr]   Downloaded solana-config-program v2.0.25
[INFO] [stderr]   Downloaded spl-associated-token-account v4.0.0
[INFO] [stderr]   Downloaded spl-token-group-interface v0.3.0
[INFO] [stderr]   Downloaded compression-codecs v0.4.36
[INFO] [stderr]   Downloaded spl-memo v5.0.0
[INFO] [stderr]   Downloaded borsh v1.5.5
[INFO] [stderr]   Downloaded solana-tpu-client v2.0.25
[INFO] [stderr]   Downloaded tokio-serde v0.8.0
[INFO] [stderr]   Downloaded filetime v0.2.27
[INFO] [stderr]   Downloaded enum-iterator-derive v1.5.0
[INFO] [stderr]   Downloaded solana-nohash-hasher v0.2.1
[INFO] [stderr]   Downloaded spl-type-length-value v0.5.0
[INFO] [stderr]   Downloaded spl-token-metadata-interface v0.4.0
[INFO] [stderr]   Downloaded solana-zk-elgamal-proof-program v2.0.25
[INFO] [stderr]   Downloaded solana-poseidon v2.0.25
[INFO] [stderr]   Downloaded solana-system-program v2.0.25
[INFO] [stderr]   Downloaded solana-compute-budget v2.0.25
[INFO] [stderr]   Downloaded solana-curve25519 v2.0.25
[INFO] [stderr]   Downloaded spl-discriminator v0.3.0
[INFO] [stderr]   Downloaded prost v0.11.9
[INFO] [stderr]   Downloaded solana-loader-v4-program v2.0.25
[INFO] [stderr]   Downloaded solana-type-overrides v2.0.25
[INFO] [stderr]   Downloaded uint v0.10.0
[INFO] [stderr]   Downloaded solana-thin-client v2.0.25
[INFO] [stderr]   Downloaded solana-zk-sdk v2.0.25
[INFO] [stderr]   Downloaded solana-udp-client v2.0.25
[INFO] [stderr]   Downloaded solana-rpc-client-api v2.0.25
[INFO] [stderr]   Downloaded solana-address-lookup-table-program v2.0.25
[INFO] [stderr]   Downloaded solana-cost-model v2.0.25
[INFO] [stderr]   Downloaded spl-pod v0.4.0
[INFO] [stderr]   Downloaded solana-sdk-macro v2.0.25
[INFO] [stderr]   Downloaded spl-type-length-value v0.6.0
[INFO] [stderr]   Downloaded aquamarine v0.3.3
[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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+4cf5f9580233c36f6bc8db76e282ba8a1c1ea491" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 895be3f4db7d1712a5a6880b03a010ec0637801746d6d4370a30dc536608238f
[INFO] running `Command { std: "docker" "start" "-a" "895be3f4db7d1712a5a6880b03a010ec0637801746d6d4370a30dc536608238f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "895be3f4db7d1712a5a6880b03a010ec0637801746d6d4370a30dc536608238f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "895be3f4db7d1712a5a6880b03a010ec0637801746d6d4370a30dc536608238f", kill_on_drop: false }`
[INFO] [stdout] 895be3f4db7d1712a5a6880b03a010ec0637801746d6d4370a30dc536608238f
[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=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" "+4cf5f9580233c36f6bc8db76e282ba8a1c1ea491" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] f75bba00e56d4e9ee2caac2c97e7b0032d2dfbec320a6f5f1a9595a8d56da96b
[INFO] running `Command { std: "docker" "start" "-a" "f75bba00e56d4e9ee2caac2c97e7b0032d2dfbec320a6f5f1a9595a8d56da96b", kill_on_drop: false }`
[INFO] [stderr]    Compiling quote v1.0.44
[INFO] [stderr]    Compiling libc v0.2.180
[INFO] [stderr]    Compiling serde_core v1.0.228
[INFO] [stderr]    Compiling serde v1.0.228
[INFO] [stderr]    Compiling proc-macro2 v1.0.106
[INFO] [stderr]    Compiling num-traits v0.2.19
[INFO] [stderr]    Compiling semver v1.0.27
[INFO] [stderr]    Compiling zerocopy v0.8.38
[INFO] [stderr]    Compiling generic-array v0.14.7
[INFO] [stderr]    Compiling indexmap v2.7.1
[INFO] [stderr]    Compiling crunchy v0.2.4
[INFO] [stderr]    Compiling winnow v0.7.14
[INFO] [stderr]    Compiling subtle v2.6.1
[INFO] [stderr]    Compiling rustc_version v0.4.1
[INFO] [stderr]    Compiling toml_datetime v0.6.11
[INFO] [stderr]    Compiling toml_write v0.1.2
[INFO] [stderr]    Compiling memoffset v0.9.1
[INFO] [stderr]    Compiling borsh v1.5.5
[INFO] [stderr]    Compiling zmij v1.0.19
[INFO] [stderr]    Compiling solana-program v2.0.25
[INFO] [stderr]     Checking bs58 v0.5.1
[INFO] [stderr]     Checking iana-time-zone v0.1.65
[INFO] [stderr]    Compiling solana-sdk v2.0.25
[INFO] [stderr]     Checking qstring v0.7.2
[INFO] [stderr]     Checking itertools v0.12.1
[INFO] [stderr]     Checking smallvec v1.15.1
[INFO] [stderr]    Compiling digest v0.9.0
[INFO] [stderr]     Checking scopeguard v1.2.0
[INFO] [stderr]    Compiling libsecp256k1-core v0.2.2
[INFO] [stderr]     Checking num-integer v0.1.46
[INFO] [stderr]     Checking lock_api v0.4.14
[INFO] [stderr]     Checking slab v0.4.12
[INFO] [stderr]     Checking tracing-core v0.1.36
[INFO] [stderr]     Checking foldhash v0.1.3
[INFO] [stderr]    Compiling syn v2.0.114
[INFO] [stderr]    Compiling syn v1.0.109
[INFO] [stderr]     Checking http v0.2.12
[INFO] [stderr]     Checking hashbrown v0.15.2
[INFO] [stderr]     Checking crossbeam-channel v0.5.15
[INFO] [stderr]     Checking num-bigint v0.4.6
[INFO] [stderr]     Checking simd-adler32 v0.3.8
[INFO] [stderr]    Compiling jobserver v0.1.32
[INFO] [stderr]     Checking brotli-decompressor v5.0.0
[INFO] [stderr]     Checking miniz_oxide v0.8.9
[INFO] [stderr]     Checking getrandom v0.2.17
[INFO] [stderr]     Checking getrandom v0.1.16
[INFO] [stderr]     Checking rand_core v0.6.4
[INFO] [stderr]    Compiling cc v1.2.55
[INFO] [stderr]     Checking ahash v0.8.11
[INFO] [stderr]     Checking bitflags v2.10.0
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]    Compiling libsecp256k1-gen-ecmult v0.2.1
[INFO] [stderr]    Compiling libsecp256k1-gen-genmult v0.2.1
[INFO] [stderr]     Checking hashbrown v0.13.2
[INFO] [stderr]     Checking serde_bytes v0.11.19
[INFO] [stderr]     Checking serde_json v1.0.149
[INFO] [stderr]    Compiling libsecp256k1 v0.6.0
[INFO] [stderr]     Checking memmap2 v0.5.10
[INFO] [stderr]     Checking parking_lot_core v0.9.12
[INFO] [stderr]     Checking errno v0.3.14
[INFO] [stderr]     Checking socket2 v0.6.2
[INFO] [stderr]     Checking mio v1.1.1
[INFO] [stderr]     Checking signal-hook-registry v1.4.8
[INFO] [stderr]    Compiling toml_edit v0.22.27
[INFO] [stderr]     Checking parking_lot v0.12.5
[INFO] [stderr]     Checking socket2 v0.5.10
[INFO] [stderr]    Compiling mime_guess v2.0.5
[INFO] [stderr]     Checking flate2 v1.1.9
[INFO] [stderr]     Checking brotli v8.0.2
[INFO] [stderr]     Checking http-body v0.4.6
[INFO] [stderr]     Checking compression-core v0.4.31
[INFO] [stderr]    Compiling block-buffer v0.10.4
[INFO] [stderr]    Compiling crypto-common v0.1.7
[INFO] [stderr]    Compiling num-bigint v0.2.6
[INFO] [stderr]     Checking ryu v1.0.22
[INFO] [stderr]    Compiling digest v0.10.7
[INFO] [stderr]    Compiling num-rational v0.2.4
[INFO] [stderr]    Compiling num-complex v0.2.4
[INFO] [stderr]    Compiling sha2 v0.10.9
[INFO] [stderr]     Checking gethostname v0.2.3
[INFO] [stderr]     Checking num-iter v0.1.45
[INFO] [stderr]    Compiling solana-compute-budget v2.0.25
[INFO] [stderr]    Compiling solana-vote v2.0.25
[INFO] [stderr]     Checking combine v3.8.1
[INFO] [stderr]    Compiling solana-program-runtime v2.0.25
[INFO] [stderr]     Checking rustc-demangle v0.1.27
[INFO] [stderr]     Checking regex-automata v0.4.14
[INFO] [stderr]    Compiling rustix v0.38.44
[INFO] [stderr]     Checking solana-security-txt v1.1.2
[INFO] [stderr]    Compiling solana-vote-program v2.0.25
[INFO] [stderr]    Compiling toml v0.5.11
[INFO] [stderr]    Compiling solana-version v2.0.25
[INFO] [stderr]    Compiling nix v0.28.0
[INFO] [stderr]     Checking atty v0.2.14
[INFO] [stderr]     Checking linux-raw-sys v0.4.15
[INFO] [stderr]     Checking nom v7.1.3
[INFO] [stderr]     Checking console v0.15.11
[INFO] [stderr]    Compiling anyhow v1.0.100
[INFO] [stderr]     Checking num_cpus v1.17.0
[INFO] [stderr]     Checking task-local-extensions v0.1.4
[INFO] [stderr]    Compiling blake3 v1.5.5
[INFO] [stderr]    Compiling ring v0.17.14
[INFO] [stderr]    Compiling zstd-sys v2.0.16+zstd.1.5.7
[INFO] [stderr]     Checking data-encoding v2.10.0
[INFO] [stderr]     Checking time v0.3.36
[INFO] [stderr]     Checking num v0.2.1
[INFO] [stderr]    Compiling proc-macro-crate v0.1.5
[INFO] [stderr]     Checking percentage v0.1.0
[INFO] [stderr] error: could not compile `brotli` (lib)
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `/opt/rustwide/rustup-home/toolchains/4cf5f9580233c36f6bc8db76e282ba8a1c1ea491/bin/rustc --crate-name brotli --edition=2015 /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/brotli-8.0.2/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --crate-type lib --emit=dep-info,metadata -C embed-bitcode=no -C debuginfo=2 --cfg 'feature="alloc-stdlib"' --cfg 'feature="default"' --cfg 'feature="std"' --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values("alloc-stdlib", "benchmark", "billing", "default", "disable-timer", "disallow_large_window_size", "external-literal-probability", "ffi-api", "float64", "floating_point_context_mixing", "no-stdlib-ffi-binding", "pass-through-ffi-panics", "seccomp", "sha2", "simd", "std", "validation", "vector_scratch_space"))' -C metadata=da133c1d299f2c7a -C extra-filename=-d813022d176a8d57 --out-dir /opt/rustwide/target/debug/deps -L dependency=/opt/rustwide/target/debug/deps --extern alloc_no_stdlib=/opt/rustwide/target/debug/deps/liballoc_no_stdlib-7b1bd6f28b6396be.rmeta --extern alloc_stdlib=/opt/rustwide/target/debug/deps/liballoc_stdlib-c67ef39ef9e0d8f1.rmeta --extern brotli_decompressor=/opt/rustwide/target/debug/deps/libbrotli_decompressor-b49ac68ef342ea51.rmeta --cap-lints allow --cap-lints=forbid` (signal: 9, SIGKILL: kill)
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] running `Command { std: "docker" "inspect" "f75bba00e56d4e9ee2caac2c97e7b0032d2dfbec320a6f5f1a9595a8d56da96b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f75bba00e56d4e9ee2caac2c97e7b0032d2dfbec320a6f5f1a9595a8d56da96b", kill_on_drop: false }`
[INFO] [stdout] f75bba00e56d4e9ee2caac2c97e7b0032d2dfbec320a6f5f1a9595a8d56da96b