[INFO] cloning repository https://github.com/cronokirby/standard-penumbra-explorer [INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/cronokirby/standard-penumbra-explorer" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fcronokirby%2Fstandard-penumbra-explorer", kill_on_drop: false }` [INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fcronokirby%2Fstandard-penumbra-explorer'... [INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }` [INFO] [stdout] d147644a39ca81b50f74b29f9a32ba5e24a523ed [INFO] checking cronokirby/standard-penumbra-explorer against try#44f3504e96c944ae54fc72b5f5008f53f7eda001 for pr-136776 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fcronokirby%2Fstandard-penumbra-explorer" "/workspace/builds/worker-5-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-5-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/cronokirby/standard-penumbra-explorer on toolchain 44f3504e96c944ae54fc72b5f5008f53f7eda001 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+44f3504e96c944ae54fc72b5f5008f53f7eda001" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/cronokirby/standard-penumbra-explorer [INFO] finished tweaking git repo https://github.com/cronokirby/standard-penumbra-explorer [INFO] tweaked toml for git repo https://github.com/cronokirby/standard-penumbra-explorer written to /workspace/builds/worker-5-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/cronokirby/standard-penumbra-explorer 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" "+44f3504e96c944ae54fc72b5f5008f53f7eda001" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-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@sha256:3959728d45483eb673ba100a951a6b9f5012970368db2a9e08e0ac9b67c8a5ad" "/opt/rustwide/cargo-home/bin/cargo" "+44f3504e96c944ae54fc72b5f5008f53f7eda001" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] 29103b8a1875a4a22f5122f33e098d448cc0bd40190f519dedcd12ad4811d4b9 [INFO] running `Command { std: "docker" "start" "-a" "29103b8a1875a4a22f5122f33e098d448cc0bd40190f519dedcd12ad4811d4b9", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "29103b8a1875a4a22f5122f33e098d448cc0bd40190f519dedcd12ad4811d4b9", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "29103b8a1875a4a22f5122f33e098d448cc0bd40190f519dedcd12ad4811d4b9", kill_on_drop: false }` [INFO] [stdout] 29103b8a1875a4a22f5122f33e098d448cc0bd40190f519dedcd12ad4811d4b9 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-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=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@sha256:3959728d45483eb673ba100a951a6b9f5012970368db2a9e08e0ac9b67c8a5ad" "/opt/rustwide/cargo-home/bin/cargo" "+44f3504e96c944ae54fc72b5f5008f53f7eda001" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] ea8051f21d203a74b2501dd52ef82324a95d56a3eaabe8cddbe5f06fcf9eb47b [INFO] running `Command { std: "docker" "start" "-a" "ea8051f21d203a74b2501dd52ef82324a95d56a3eaabe8cddbe5f06fcf9eb47b", kill_on_drop: false }` [INFO] [stderr] Compiling unicode-ident v1.0.12 [INFO] [stderr] Compiling proc-macro2 v1.0.86 [INFO] [stderr] Compiling version_check v0.9.4 [INFO] [stderr] Compiling libc v0.2.155 [INFO] [stderr] Compiling autocfg v1.3.0 [INFO] [stderr] Compiling typenum v1.17.0 [INFO] [stderr] Checking cfg-if v1.0.0 [INFO] [stderr] Compiling serde v1.0.204 [INFO] [stderr] Checking subtle v2.4.1 [INFO] [stderr] Compiling syn v1.0.109 [INFO] [stderr] Checking const-oid v0.9.6 [INFO] [stderr] Checking once_cell v1.19.0 [INFO] [stderr] Compiling paste v1.0.15 [INFO] [stderr] Compiling anyhow v1.0.86 [INFO] [stderr] Checking memchr v2.7.4 [INFO] [stderr] Checking pin-project-lite v0.2.14 [INFO] [stderr] Checking itoa v1.0.11 [INFO] [stderr] Checking cpufeatures v0.2.12 [INFO] [stderr] Checking ppv-lite86 v0.2.17 [INFO] [stderr] Compiling generic-array v0.14.7 [INFO] [stderr] Compiling ahash v0.8.11 [INFO] [stderr] Checking tracing-core v0.1.32 [INFO] [stderr] Checking log v0.4.22 [INFO] [stderr] Compiling serde_json v1.0.120 [INFO] [stderr] Checking ryu v1.0.18 [INFO] [stderr] Compiling cc v1.1.0 [INFO] [stderr] Checking smallvec v1.13.2 [INFO] [stderr] Checking futures-core v0.3.30 [INFO] [stderr] Checking hex v0.4.3 [INFO] [stderr] Checking zerocopy v0.7.35 [INFO] [stderr] Compiling num-traits v0.2.19 [INFO] [stderr] Compiling slab v0.4.9 [INFO] [stderr] Checking futures-sink v0.3.30 [INFO] [stderr] Checking futures-channel v0.3.30 [INFO] [stderr] Checking pin-utils v0.1.0 [INFO] [stderr] Checking futures-task v0.3.30 [INFO] [stderr] Checking futures-io v0.3.30 [INFO] [stderr] Checking iana-time-zone v0.1.60 [INFO] [stderr] Checking regex-syntax v0.6.29 [INFO] [stderr] Checking byteorder v1.5.0 [INFO] [stderr] Checking aho-corasick v1.1.3 [INFO] [stderr] Checking regex-syntax v0.8.4 [INFO] [stderr] Compiling quote v1.0.36 [INFO] [stderr] Compiling lock_api v0.4.12 [INFO] [stderr] Checking lazy_static v1.5.0 [INFO] [stderr] Compiling thiserror v1.0.61 [INFO] [stderr] Compiling parking_lot_core v0.9.10 [INFO] [stderr] Compiling syn v2.0.70 [INFO] [stderr] Checking getrandom v0.2.15 [INFO] [stderr] Checking sharded-slab v0.1.7 [INFO] [stderr] Checking thread_local v1.1.8 [INFO] [stderr] Checking base64 v0.21.7 [INFO] [stderr] Checking num-integer v0.1.46 [INFO] [stderr] Compiling rand_core v0.6.4 [INFO] [stderr] Checking num-bigint v0.4.6 [INFO] [stderr] Checking rand_chacha v0.3.1 [INFO] [stderr] Compiling eyre v0.6.12 [INFO] [stderr] Checking tracing-log v0.1.4 [INFO] [stderr] Compiling num-conv v0.1.0 [INFO] [stderr] Checking hashbrown v0.13.2 [INFO] [stderr] Compiling time-core v0.1.2 [INFO] [stderr] Checking ansi_term v0.12.1 [INFO] [stderr] Checking opaque-debug v0.3.1 [INFO] [stderr] Checking indenter v0.3.3 [INFO] [stderr] Checking powerfmt v0.2.0 [INFO] [stderr] Compiling bytes v1.6.0 [INFO] [stderr] Checking arrayref v0.3.7 [INFO] [stderr] Checking rand v0.8.5 [INFO] [stderr] Compiling time-macros v0.2.18 [INFO] [stderr] Checking deranged v0.3.11 [INFO] [stderr] Compiling allocator-api2 v0.2.18 [INFO] [stderr] Checking regex-automata v0.1.10 [INFO] [stderr] Checking flex-error v0.4.4 [INFO] [stderr] Checking constant_time_eq v0.3.0 [INFO] [stderr] Checking arrayvec v0.7.4 [INFO] [stderr] Checking subtle-ng v2.5.0 [INFO] [stderr] Compiling safe-proc-macro2 v1.0.67 [INFO] [stderr] Checking regex-automata v0.4.7 [INFO] [stderr] Compiling equivalent v1.0.1 [INFO] [stderr] Compiling blake3 v1.5.1 [INFO] [stderr] Compiling hashbrown v0.14.5 [INFO] [stderr] Compiling bitflags v2.6.0 [INFO] [stderr] Checking ark-std v0.4.0 [INFO] [stderr] Compiling rustix v0.38.34 [INFO] [stderr] Compiling unicode-segmentation v1.11.0 [INFO] [stderr] Compiling block-buffer v0.10.4 [INFO] [stderr] Compiling crypto-common v0.1.6 [INFO] [stderr] Compiling crunchy v0.2.2 [INFO] [stderr] Compiling digest v0.10.7 [INFO] [stderr] Compiling linux-raw-sys v0.4.14 [INFO] [stderr] Checking keccak v0.1.5 [INFO] [stderr] Checking static_assertions v1.1.0 [INFO] [stderr] Checking matchers v0.0.1 [INFO] [stderr] Checking scopeguard v1.2.0 [INFO] [stderr] Compiling ring v0.17.8 [INFO] [stderr] Compiling fastrand v2.1.0 [INFO] [stderr] Checking rustc-hex v2.1.0 [INFO] [stderr] Compiling heck v0.4.1 [INFO] [stderr] Checking fixed-hash v0.8.0 [INFO] [stderr] Checking uint v0.9.5 [INFO] [stderr] Checking dyn-clone v1.0.17 [INFO] [stderr] Compiling prettyplease v0.2.20 [INFO] [stderr] Checking parking_lot v0.12.3 [INFO] [stderr] Compiling indexmap v2.2.6 [INFO] [stderr] Compiling fixedbitset v0.4.2 [INFO] [stderr] Compiling multimap v0.10.0 [INFO] [stderr] Compiling radium v0.7.0 [INFO] [stderr] Checking time v0.3.36 [INFO] [stderr] Compiling safe-quote v1.0.15 [INFO] [stderr] Checking unicode-xid v0.1.0 [INFO] [stderr] Compiling crossbeam-utils v0.8.20 [INFO] [stderr] Compiling safe-regex-compiler v0.2.6 [INFO] [stderr] Compiling heck v0.5.0 [INFO] [stderr] Checking tap v1.0.1 [INFO] [stderr] Checking proc-macro2 v0.1.10 [INFO] [stderr] Compiling num-iter v0.1.45 [INFO] [stderr] Compiling num-complex v0.4.6 [INFO] [stderr] Checking socket2 v0.5.7 [INFO] [stderr] Checking mio v0.8.11 [INFO] [stderr] Checking regex v1.10.5 [INFO] [stderr] Checking num_cpus v1.16.0 [INFO] [stderr] Checking signal-hook-registry v1.4.2 [INFO] [stderr] Compiling petgraph v0.6.5 [INFO] [stderr] Compiling num-rational v0.4.2 [INFO] [stderr] Checking wyz v0.5.1 [INFO] [stderr] Checking blake2b_simd v1.0.2 [INFO] [stderr] Compiling safe-regex-macro v0.2.6 [INFO] [stderr] Compiling tinyvec_macros v0.1.1 [INFO] [stderr] Compiling rustls v0.21.12 [INFO] [stderr] Checking funty v2.0.0 [INFO] [stderr] Checking arrayvec v0.5.2 [INFO] [stderr] Checking constant_time_eq v0.1.5 [INFO] [stderr] Compiling tinyvec v1.8.0 [INFO] [stderr] Compiling penumbra-proto v0.79.0 (https://github.com/penumbra-zone/penumbra?branch=pindexer-tweaks#a069ba19) [INFO] [stderr] Checking safe-regex v0.2.6 [INFO] [stderr] Compiling strsim v0.11.1 [INFO] [stderr] Checking bech32 v0.8.1 [INFO] [stderr] Compiling untrusted v0.9.0 [INFO] [stderr] Compiling fnv v1.0.7 [INFO] [stderr] Compiling ident_case v1.0.1 [INFO] [stderr] Compiling num v0.4.3 [INFO] [stderr] Checking blake2b_simd v0.5.11 [INFO] [stderr] Compiling spin v0.9.8 [INFO] [stderr] Checking ff v0.13.0 [INFO] [stderr] Checking base16ct v0.2.0 [INFO] [stderr] Compiling unicode-bidi v0.3.15 [INFO] [stderr] Checking group v0.13.0 [INFO] [stderr] Checking bitmaps v2.1.0 [INFO] [stderr] Checking bitvec v1.0.1 [INFO] [stderr] Compiling tempfile v3.10.1 [INFO] [stderr] Compiling im v15.1.0 [INFO] [stderr] Compiling unicode-normalization v0.1.23 [INFO] [stderr] Compiling minimal-lexical v0.2.1 [INFO] [stderr] Compiling percent-encoding v2.3.1 [INFO] [stderr] Checking sized-chunks v0.6.5 [INFO] [stderr] Checking form_urlencoded v1.2.1 [INFO] [stderr] Compiling tokio v1.38.0 [INFO] [stderr] Checking rand_xoshiro v0.6.0 [INFO] [stderr] Compiling nom v7.1.3 [INFO] [stderr] Compiling unicode_categories v0.1.1 [INFO] [stderr] Compiling rustversion v1.0.17 [INFO] [stderr] Compiling idna v0.5.0 [INFO] [stderr] Compiling darling_core v0.20.10 [INFO] [stderr] Compiling crc-catalog v2.4.0 [INFO] [stderr] Compiling sha2 v0.10.8 [INFO] [stderr] Compiling chrono v0.4.38 [INFO] [stderr] Compiling crc v3.2.1 [INFO] [stderr] Compiling futures-util v0.3.30 [INFO] [stderr] Compiling crossbeam-queue v0.3.11 [INFO] [stderr] Compiling rustls-pemfile v1.0.4 [INFO] [stderr] Compiling futures-intrusive v0.5.0 [INFO] [stderr] Compiling url v2.5.2 [INFO] [stderr] Compiling hashlink v0.8.4 [INFO] [stderr] Compiling hmac v0.12.1 [INFO] [stderr] Checking ibig v0.3.6 [INFO] [stderr] Compiling atoi v2.0.0 [INFO] [stderr] Compiling proc-macro-error-attr v1.0.4 [INFO] [stderr] Checking tower-service v0.3.2 [INFO] [stderr] Checking tower-layer v0.3.2 [INFO] [stderr] Checking hash_hasher v2.0.3 [INFO] [stderr] Compiling unicode-properties v0.1.1 [INFO] [stderr] Compiling webpki-roots v0.25.4 [INFO] [stderr] Compiling rustls-webpki v0.101.7 [INFO] [stderr] Compiling sct v0.7.1 [INFO] [stderr] Compiling event-listener v2.5.3 [INFO] [stderr] Checking ethnum v1.5.0 [INFO] [stderr] Compiling stringprep v0.1.5 [INFO] [stderr] Compiling hkdf v0.12.4 [INFO] [stderr] Compiling sqlformat v0.2.4 [INFO] [stderr] Compiling md-5 v0.10.6 [INFO] [stderr] Compiling proc-macro-error v1.0.4 [INFO] [stderr] Compiling home v0.5.9 [INFO] [stderr] Compiling whoami v1.5.1 [INFO] [stderr] Compiling dotenvy v0.15.7 [INFO] [stderr] Compiling ark-serialize-derive v0.4.2 [INFO] [stderr] Compiling ark-ff-macros v0.4.2 [INFO] [stderr] Compiling derivative v2.2.0 [INFO] [stderr] Compiling ark-ff-asm v0.4.2 [INFO] [stderr] Compiling num-derive v0.3.3 [INFO] [stderr] Compiling serde_derive v1.0.204 [INFO] [stderr] Compiling zeroize_derive v1.4.2 [INFO] [stderr] Compiling tracing-attributes v0.1.27 [INFO] [stderr] Compiling futures-macro v0.3.30 [INFO] [stderr] Compiling thiserror-impl v1.0.61 [INFO] [stderr] Compiling serde_repr v0.1.19 [INFO] [stderr] Compiling displaydoc v0.2.5 [INFO] [stderr] Checking zeroize v1.8.1 [INFO] [stderr] Checking subtle-encoding v0.5.1 [INFO] [stderr] Compiling ark-serialize v0.4.2 [INFO] [stderr] Compiling derive_more v0.99.18 [INFO] [stderr] Compiling async-trait v0.1.81 [INFO] [stderr] Compiling pin-project-internal v1.1.5 [INFO] [stderr] Compiling tokio-macros v2.3.0 [INFO] [stderr] Compiling merlin v3.0.0 [INFO] [stderr] Checking der v0.7.9 [INFO] [stderr] Compiling tokio-stream v0.1.15 [INFO] [stderr] Checking tracing v0.1.40 [INFO] [stderr] Compiling darling_macro v0.20.10 [INFO] [stderr] Checking digest v0.9.0 [INFO] [stderr] Checking block-buffer v0.9.0 [INFO] [stderr] Checking crypto-bigint v0.5.5 [INFO] [stderr] Checking cipher v0.3.0 [INFO] [stderr] Checking universal-hash v0.4.1 [INFO] [stderr] Compiling darling v0.20.10 [INFO] [stderr] Checking curve25519-dalek-ng v4.1.1 [INFO] [stderr] Checking sha2 v0.9.9 [INFO] [stderr] Checking inout v0.1.3 [INFO] [stderr] Compiling serde_with_macros v3.8.3 [INFO] [stderr] Checking chacha20 v0.8.2 [INFO] [stderr] Checking blake2 v0.10.6 [INFO] [stderr] Checking signature v2.2.0 [INFO] [stderr] Checking ripemd v0.1.3 [INFO] [stderr] Checking ed25519 v2.2.3 [INFO] [stderr] Checking sha3 v0.10.8 [INFO] [stderr] Checking rfc6979 v0.4.0 [INFO] [stderr] Checking bs58 v0.5.1 [INFO] [stderr] Checking pbkdf2 v0.12.2 [INFO] [stderr] Checking cipher v0.4.4 [INFO] [stderr] Checking poly1305 v0.7.2 [INFO] [stderr] Checking aead v0.4.3 [INFO] [stderr] Checking sec1 v0.7.3 [INFO] [stderr] Checking chacha20poly1305 v0.9.1 [INFO] [stderr] Checking aes v0.8.4 [INFO] [stderr] Checking pin-project v1.1.5 [INFO] [stderr] Checking ed25519-consensus v2.1.0 [INFO] [stderr] Checking f4jumble v0.0.0 (https://github.com/zcash/librustzcash?rev=2425a0869098e3b0588ccd73c42716bcf418612c#2425a086) [INFO] [stderr] Compiling indexmap v1.9.3 [INFO] [stderr] Compiling httparse v1.9.4 [INFO] [stderr] Checking metrics v0.22.3 [INFO] [stderr] Compiling penumbra-proof-params v0.79.0 (https://github.com/penumbra-zone/penumbra?branch=pindexer-tweaks#a069ba19) [INFO] [stderr] Checking os_str_bytes v6.6.1 [INFO] [stderr] Checking overload v0.1.1 [INFO] [stderr] Checking hashbrown v0.12.3 [INFO] [stderr] Checking nu-ansi-term v0.46.0 [INFO] [stderr] Compiling async-stream-impl v0.3.5 [INFO] [stderr] Compiling axum-core v0.4.3 [INFO] [stdout] error[E0521]: borrowed data escapes outside of associated function [INFO] [stdout] --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/metrics-0.22.3/src/recorder/mod.rs:77:9 [INFO] [stdout] | [INFO] [stdout] 71 | fn new(recorder: &dyn Recorder) -> Self { [INFO] [stdout] | -------- - let's call the lifetime of this reference `'1` [INFO] [stdout] | | [INFO] [stdout] | `recorder` is a reference that is only valid in the associated function body [INFO] [stdout] ... [INFO] [stdout] 77 | / LOCAL_RECORDER.with(|local_recorder| { [INFO] [stdout] 78 | | local_recorder.set(Some(recorder_ptr)); [INFO] [stdout] 79 | | }); [INFO] [stdout] | | ^ [INFO] [stdout] | | | [INFO] [stdout] | |__________`recorder` escapes the associated function body here [INFO] [stdout] | argument requires that `'1` must outlive `'static` [INFO] [stdout] | [INFO] [stdout] = note: requirement occurs because of the type `Cell>>`, which makes the generic argument `Option>` invariant [INFO] [stdout] = note: the struct `Cell` is invariant over the parameter `T` [INFO] [stdout] = help: see for more information about variance [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Checking matchers v0.1.0 [INFO] [stdout] For more information about this error, try `rustc --explain E0521`. [INFO] [stdout] [INFO] [stderr] Compiling clap_derive v3.2.25 [INFO] [stderr] Checking atty v0.2.14 [INFO] [stderr] error: could not compile `metrics` (lib) due to 1 previous error [INFO] [stderr] warning: build failed, waiting for other jobs to finish... [INFO] running `Command { std: "docker" "inspect" "ea8051f21d203a74b2501dd52ef82324a95d56a3eaabe8cddbe5f06fcf9eb47b", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "ea8051f21d203a74b2501dd52ef82324a95d56a3eaabe8cddbe5f06fcf9eb47b", kill_on_drop: false }` [INFO] [stdout] ea8051f21d203a74b2501dd52ef82324a95d56a3eaabe8cddbe5f06fcf9eb47b