[INFO] cloning repository https://github.com/Fi3/kteach-r
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/Fi3/kteach-r" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FFi3%2Fkteach-r", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FFi3%2Fkteach-r'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] a4eb5921b00e9049479a8468dc1751876e0aca27
[INFO] documenting Fi3/kteach-r against beta-2023-04-20 for beta-1.70-rustdoc-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FFi3%2Fkteach-r" "/workspace/builds/worker-0-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-0-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/Fi3/kteach-r on toolchain beta-2023-04-20
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2023-04-20" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/Fi3/kteach-r
[INFO] finished tweaking git repo https://github.com/Fi3/kteach-r
[INFO] tweaked toml for git repo https://github.com/Fi3/kteach-r written to /workspace/builds/worker-0-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/Fi3/kteach-r 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-2023-04-20" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded ringbuf v0.2.2
[INFO] [stderr]   Downloaded coremidi v0.4.0
[INFO] [stderr]   Downloaded unic-langid v0.9.0
[INFO] [stderr]   Downloaded coremidi-sys v2.0.2
[INFO] [stderr]   Downloaded unic-langid-impl v0.9.0
[INFO] [stderr]   Downloaded intl_pluralrules v7.0.0
[INFO] [stderr]   Downloaded symphonia-bundle-mp3 v0.1.0
[INFO] [stderr]   Downloaded piet-coregraphics v0.2.0-pre6
[INFO] [stderr]   Downloaded dodrio v0.2.0
[INFO] [stderr]   Downloaded glow_glyph v0.4.0
[INFO] [stderr]   Downloaded utf16_lit v1.0.1
[INFO] [stderr]   Downloaded piet v0.2.0-pre6
[INFO] [stderr]   Downloaded font-kit v0.8.0
[INFO] [stderr]   Downloaded smithay-clipboard v0.6.1
[INFO] [stderr]   Downloaded glow v0.6.1
[INFO] [stderr]   Downloaded gfx-backend-dx11 v0.6.15
[INFO] [stderr]   Downloaded glyph_brush_draw_cache v0.1.3
[INFO] [stderr]   Downloaded slotmap v0.4.0
[INFO] [stderr]   Downloaded clipboard_wayland v0.1.2
[INFO] [stderr]   Downloaded anyhow v1.0.34
[INFO] [stderr]   Downloaded gdk-pixbuf v0.9.0
[INFO] [stderr]   Downloaded inplace_it v0.3.2
[INFO] [stderr]   Downloaded longest-increasing-subsequence v0.1.0
[INFO] [stderr]   Downloaded ttf-parser v0.8.3
[INFO] [stderr]   Downloaded atk-sys v0.10.0
[INFO] [stderr]   Downloaded glam v0.10.2
[INFO] [stderr]   Downloaded euclid v0.22.1
[INFO] [stderr]   Downloaded spirv_cross v0.22.1
[INFO] [stderr]   Downloaded bytemuck_derive v1.0.0
[INFO] [stderr]   Downloaded associative-cache v1.0.1
[INFO] [stderr]   Downloaded clipboard_macos v0.1.0
[INFO] [stderr]   Downloaded gtk v0.9.2
[INFO] [stderr]   Downloaded gdk-sys v0.10.0
[INFO] [stderr]   Downloaded gio-sys v0.10.1
[INFO] [stderr]   Downloaded gtk-sys v0.10.0
[INFO] [stderr]   Downloaded piet-common v0.2.0-pre6
[INFO] [stderr]   Downloaded ab_glyph v0.2.6
[INFO] [stderr]   Downloaded gdk v0.13.2
[INFO] [stderr]   Downloaded gdk-pixbuf-sys v0.10.0
[INFO] [stderr]   Downloaded pango-sys v0.10.0
[INFO] [stderr]   Downloaded unic-bidi v0.9.0
[INFO] [stderr]   Downloaded gio v0.9.1
[INFO] [stderr]   Downloaded owned_ttf_parser v0.8.0
[INFO] [stderr]   Downloaded pango v0.9.1
[INFO] [stderr]   Downloaded atk v0.9.0
[INFO] [stderr]   Downloaded time v0.2.23
[INFO] [stderr]   Downloaded standback v0.2.13
[INFO] [stderr]   Downloaded keyboard-types v0.5.0
[INFO] [stderr]   Downloaded error-code v2.0.2
[INFO] [stderr]   Downloaded clipboard_x11 v0.1.0
[INFO] [stderr]   Downloaded piet-cairo v0.2.0-pre6
[INFO] [stderr]   Downloaded piet-direct2d v0.2.0-pre6
[INFO] [stderr]   Downloaded wmidi v4.0.1
[INFO] [stderr]   Downloaded glyph_brush v0.7.0
[INFO] [stderr]   Downloaded gfx-backend-metal v0.6.4
[INFO] [stderr]   Downloaded clipboard-win v4.0.3
[INFO] [stderr]   Downloaded fluent-bundle v0.12.0
[INFO] [stderr]   Downloaded core-text v19.1.0
[INFO] [stderr]   Downloaded symphonia-bundle-flac v0.1.0
[INFO] [stderr]   Downloaded symphonia-format-ogg v0.1.0
[INFO] [stderr]   Downloaded kurbo v0.7.1
[INFO] [stderr]   Downloaded memalloc v0.1.0
[INFO] [stderr]   Downloaded midir v0.7.0
[INFO] [stderr]   Downloaded symphonia-codec-pcm v0.1.0
[INFO] [stderr]   Downloaded symphonia-utils-xiph v0.1.0
[INFO] [stderr]   Downloaded symphonia-format-wav v0.1.0
[INFO] [stderr]   Downloaded symphonia-core v0.1.0
[INFO] [stderr]   Downloaded symphonia-metadata v0.1.0
[INFO] [stderr]   Downloaded symphonia v0.1.0
[INFO] [stderr]   Downloaded window_clipboard v0.1.3
[INFO] [stderr]   Downloaded piet-web v0.2.0-pre6
[INFO] [stderr]   Downloaded intl-memoizer v0.5.0
[INFO] [stderr]   Downloaded nfd v0.0.4
[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@sha256:5ff2268d62e97bff2cde7d5815dd6ed5b47097566f13b8d0ca110b04b60e07ed" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2023-04-20" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 4aab69b21ada6c518c12511f219c84e183afc15ea4d145c52ef664742b0d09e5
[INFO] running `Command { std: "docker" "start" "-a" "4aab69b21ada6c518c12511f219c84e183afc15ea4d145c52ef664742b0d09e5", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "4aab69b21ada6c518c12511f219c84e183afc15ea4d145c52ef664742b0d09e5", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "4aab69b21ada6c518c12511f219c84e183afc15ea4d145c52ef664742b0d09e5", kill_on_drop: false }`
[INFO] [stdout] 4aab69b21ada6c518c12511f219c84e183afc15ea4d145c52ef664742b0d09e5
[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@sha256:5ff2268d62e97bff2cde7d5815dd6ed5b47097566f13b8d0ca110b04b60e07ed" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2023-04-20" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] b73606036de41f6febd6ff1a8ed4f09b4ac481f8c43c574e863797e2ce84f6fd
[INFO] running `Command { std: "docker" "start" "-a" "b73606036de41f6febd6ff1a8ed4f09b4ac481f8c43c574e863797e2ce84f6fd", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.80
[INFO] [stderr]    Compiling syn v1.0.48
[INFO] [stderr]    Compiling log v0.4.11
[INFO] [stderr]    Compiling serde v1.0.117
[INFO] [stderr]    Compiling unicode-segmentation v1.7.1
[INFO] [stderr]    Compiling strum v0.18.0
[INFO] [stderr]    Compiling version-compare v0.0.10
[INFO] [stderr]     Checking once_cell v1.5.2
[INFO] [stderr]     Checking slab v0.4.2
[INFO] [stderr]    Compiling proc-macro-nested v0.1.6
[INFO] [stderr]     Checking futures-core v0.3.8
[INFO] [stderr]     Checking futures-sink v0.3.8
[INFO] [stderr]     Checking futures-io v0.3.8
[INFO] [stderr]     Checking smallvec v1.4.2
[INFO] [stderr]     Checking libloading v0.6.5
[INFO] [stderr]    Compiling const_fn v0.4.3
[INFO] [stderr]     Checking ab_glyph_rasterizer v0.1.4
[INFO] [stderr]    Compiling wayland-scanner v0.28.2
[INFO] [stderr]    Compiling proc-macro-error-attr v1.0.4
[INFO] [stderr]    Compiling anyhow v1.0.34
[INFO] [stderr]     Checking futures-task v0.3.8
[INFO] [stderr]     Checking futures-channel v0.3.8
[INFO] [stderr]    Compiling nix v0.18.0
[INFO] [stderr]    Compiling wayland-sys v0.28.2
[INFO] [stderr]    Compiling proc-macro-error v1.0.4
[INFO] [stderr]     Checking dlib v0.4.2
[INFO] [stderr]     Checking instant v0.1.8
[INFO] [stderr]    Compiling heck v0.3.1
[INFO] [stderr]    Compiling either v1.6.1
[INFO] [stderr]     Checking fxhash v0.2.1
[INFO] [stderr]    Compiling crossbeam-utils v0.8.0
[INFO] [stderr]    Compiling encoding_rs v0.8.26
[INFO] [stderr]     Checking symphonia-core v0.1.0
[INFO] [stderr]    Compiling nom v6.0.1
[INFO] [stderr]    Compiling itertools v0.9.0
[INFO] [stderr]     Checking scoped-tls v1.0.0
[INFO] [stderr]     Checking ttf-parser v0.6.2
[INFO] [stderr]    Compiling pathfinder_simd v0.5.0
[INFO] [stderr]     Checking lock_api v0.4.1
[INFO] [stderr]    Compiling alsa-sys v0.3.0
[INFO] [stderr]    Compiling servo-fontconfig-sys v4.0.9
[INFO] [stderr]     Checking ttf-parser v0.8.3
[INFO] [stderr]    Compiling gl_generator v0.14.0
[INFO] [stderr]    Compiling standback v0.2.13
[INFO] [stderr]    Compiling cairo-rs v0.9.1
[INFO] [stderr]     Checking num_cpus v1.13.0
[INFO] [stderr]     Checking raw-window-handle v0.3.3
[INFO] [stderr]     Checking getrandom v0.1.15
[INFO] [stderr]     Checking parking_lot_core v0.8.0
[INFO] [stderr]    Compiling wayland-client v0.28.2
[INFO] [stderr]    Compiling jobserver v0.1.21
[INFO] [stderr]    Compiling wayland-protocols v0.28.2
[INFO] [stderr]     Checking crossbeam-epoch v0.9.0
[INFO] [stderr]     Checking crossbeam-channel v0.5.0
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking owned_ttf_parser v0.6.0
[INFO] [stderr]    Compiling cc v1.0.62
[INFO] [stderr]     Checking parking_lot v0.11.0
[INFO] [stderr]     Checking rusttype v0.9.2
[INFO] [stderr]     Checking crossbeam-deque v0.8.0
[INFO] [stderr]     Checking rand_chacha v0.2.2
[INFO] [stderr]     Checking gfx-hal v0.6.0
[INFO] [stderr]     Checking symphonia-metadata v0.1.0
[INFO] [stderr]     Checking memmap v0.7.0
[INFO] [stderr]     Checking andrew v0.3.1
[INFO] [stderr]     Checking rand v0.7.3
[INFO] [stderr]     Checking rayon-core v1.9.0
[INFO] [stderr]     Checking owned_ttf_parser v0.8.0
[INFO] [stderr]     Checking nix v0.15.0
[INFO] [stderr]     Checking dirs-sys v0.3.5
[INFO] [stderr]    Compiling cmake v0.1.45
[INFO] [stderr]     Checking xcursor v0.3.3
[INFO] [stderr]     Checking ab_glyph v0.2.6
[INFO] [stderr]     Checking symphonia-utils-xiph v0.1.0
[INFO] [stderr]    Compiling glam v0.10.2
[INFO] [stderr]    Compiling x11 v2.18.2
[INFO] [stderr]    Compiling gio v0.9.1
[INFO] [stderr]     Checking iced_core v0.2.1 (https://github.com/hecrj/iced#87c9df29)
[INFO] [stderr]     Checking tinystr v0.3.4
[INFO] [stderr]     Checking pathfinder_geometry v0.5.1
[INFO] [stderr]     Checking dirs v2.0.2
[INFO] [stderr]    Compiling xcb v0.9.0
[INFO] [stderr]     Checking twox-hash v1.6.0
[INFO] [stderr]     Checking unic-langid-impl v0.9.0
[INFO] [stderr]     Checking rayon v1.5.0
[INFO] [stderr]     Checking iovec v0.1.4
[INFO] [stderr]     Checking net2 v0.2.35
[INFO] [stderr]     Checking approx v0.4.0
[INFO] [stderr]    Compiling cpal v0.13.1
[INFO] [stderr]    Compiling servo-freetype-sys v4.0.5
[INFO] [stderr]    Compiling expat-sys v2.1.6
[INFO] [stderr]    Compiling pango v0.9.1
[INFO] [stderr]     Checking float-ord v0.2.0
[INFO] [stderr]     Checking bit-vec v0.6.2
[INFO] [stderr]    Compiling gdk-pixbuf v0.9.0
[INFO] [stderr]     Checking mio v0.6.22
[INFO] [stderr]     Checking bit-set v0.5.2
[INFO] [stderr]     Checking unic-langid v0.9.0
[INFO] [stderr]     Checking glyph_brush_layout v0.2.1
[INFO] [stderr]     Checking x11-dl v2.18.5
[INFO] [stderr]     Checking freetype v0.4.1
[INFO] [stderr]     Checking iced_style v0.1.0 (https://github.com/hecrj/iced#87c9df29)
[INFO] [stderr]     Checking symphonia-format-ogg v0.1.0
[INFO] [stderr]     Checking servo-fontconfig v0.4.0
[INFO] [stderr]    Compiling toml v0.5.7
[INFO] [stderr]     Checking symphonia-bundle-flac v0.1.0
[INFO] [stderr]     Checking symphonia-bundle-mp3 v0.1.0
[INFO] [stderr]     Checking symphonia-format-wav v0.1.0
[INFO] [stderr]     Checking font-kit v0.8.0
[INFO] [stderr]     Checking wayland-commons v0.28.2
[INFO] [stderr]     Checking calloop v0.6.5
[INFO] [stderr]     Checking time v0.1.44
[INFO] [stderr]     Checking symphonia-codec-pcm v0.1.0
[INFO] [stderr]     Checking kurbo v0.7.1
[INFO] [stderr]     Checking ash v0.31.0
[INFO] [stderr]     Checking spirv_headers v1.5.0
[INFO] [stderr]     Checking ordered-float v1.1.0
[INFO] [stderr]     Checking tracing-core v0.1.17
[INFO] [stderr]    Compiling winit v0.23.0
[INFO] [stderr]    Compiling gcc v0.3.55
[INFO] [stderr]     Checking pin-project-lite v0.2.0
[INFO] [stderr]    Compiling gdk v0.13.2
[INFO] [stderr]     Checking memalloc v0.1.0
[INFO] [stderr]    Compiling atk v0.9.0
[INFO] [stderr]     Checking inplace_it v0.3.2
[INFO] [stderr]     Checking tracing v0.1.22
[INFO] [stderr]     Checking mio-extras v2.0.6
[INFO] [stderr]    Compiling proc-macro-crate v0.1.5
[INFO] [stderr]     Checking alsa v0.4.3
[INFO] [stderr]     Checking glyph_brush_draw_cache v0.1.3
[INFO] [stderr]     Checking piet v0.2.0-pre6
[INFO] [stderr]     Checking symphonia v0.1.0
[INFO] [stderr]     Checking synthesizer-io-core v0.1.0 (https://github.com/raphlinus/synthesizer-io#8bb4f5f5)
[INFO] [stderr]    Compiling synstructure v0.12.4
[INFO] [stderr]     Checking gfx-memory v0.2.2
[INFO] [stderr]     Checking glyph_brush v0.7.0
[INFO] [stderr]     Checking gfx-backend-empty v0.6.0
[INFO] [stderr]    Compiling nfd v0.0.4
[INFO] [stderr]     Checking gfx-descriptor v0.2.0
[INFO] [stderr]    Compiling glutin_egl_sys v0.1.5
[INFO] [stderr]     Checking wayland-cursor v0.28.2
[INFO] [stderr]    Compiling glutin_glx_sys v0.1.7
[INFO] [stderr]     Checking wgpu-types v0.6.1
[INFO] [stderr]    Compiling gtk v0.9.2
[INFO] [stderr]    Compiling time v0.2.23
[INFO] [stderr]     Checking ringbuf v0.2.2
[INFO] [stderr]     Checking wmidi v4.0.1
[INFO] [stderr]     Checking shared_library v0.1.9
[INFO] [stderr]     Checking type-map v0.3.0
[INFO] [stderr]     Checking euclid v0.22.1
[INFO] [stderr]     Checking typed-arena v2.0.1
[INFO] [stderr]     Checking stable_deref_trait v1.2.0
[INFO] [stderr]     Checking osmesa-sys v0.1.2
[INFO] [stderr]     Checking midir v0.7.0
[INFO] [stderr]     Checking wayland-egl v0.28.2
[INFO] [stderr]     Checking fluent-langneg v0.13.0
[INFO] [stderr]     Checking intl-memoizer v0.5.0
[INFO] [stderr]     Checking intl_pluralrules v7.0.0
[INFO] [stderr]     Checking keyboard-types v0.5.0
[INFO] [stderr]     Checking glow v0.6.1
[INFO] [stderr]     Checking fluent-syntax v0.9.3
[INFO] [stderr]     Checking simple_logger v1.11.0
[INFO] [stderr]     Checking guillotiere v0.6.0
[INFO] [stderr]    Compiling thiserror-impl v1.0.22
[INFO] [stderr]    Compiling strum_macros v0.18.0
[INFO] [stderr]    Compiling pin-project-internal v1.0.2
[INFO] [stderr]    Compiling futures-macro v0.3.8
[INFO] [stderr]    Compiling glib-macros v0.10.1
[INFO] [stderr]    Compiling bytemuck_derive v1.0.0
[INFO] [stderr]    Compiling time-macros-impl v0.1.1
[INFO] [stderr]    Compiling rental-impl v0.5.5
[INFO] [stderr]    Compiling zerocopy-derive v0.2.0
[INFO] [stderr]    Compiling druid-derive v0.3.1 (https://github.com/linebender/druid?rev=6fd8ff9c6dd4f8c628347ca7eda4f5d762ae3001#6fd8ff9c)
[INFO] [stderr]     Checking bytemuck v1.4.1
[INFO] [stderr]     Checking time-macros v0.1.1
[INFO] [stderr]     Checking glow_glyph v0.4.0
[INFO] [stderr]     Checking zerocopy v0.3.0
[INFO] [stderr]    Compiling thiserror v1.0.22
[INFO] [stderr]    Compiling system-deps v1.3.2
[INFO] [stderr]     Checking naga v0.2.0
[INFO] [stderr]     Checking pin-project v1.0.2
[INFO] [stderr]     Checking futures-util v0.3.8
[INFO] [stderr]     Checking kteach-core v0.1.0 (/opt/rustwide/workdir/kteach-core)
[INFO] [stderr]  Documenting kteach-core v0.1.0 (/opt/rustwide/workdir/kteach-core)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> kteach-core/src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(associated_type_bounds)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling glib-sys v0.10.1
[INFO] [stderr]    Compiling gobject-sys v0.10.0
[INFO] [stderr]    Compiling gio-sys v0.10.1
[INFO] [stderr]    Compiling cairo-sys-rs v0.10.0
[INFO] [stderr]    Compiling pango-sys v0.10.0
[INFO] [stderr]    Compiling gdk-pixbuf-sys v0.10.0
[INFO] [stderr]    Compiling gdk-sys v0.10.0
[INFO] [stderr]    Compiling atk-sys v0.10.0
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> kteach-core/src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(associated_type_bounds)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not document `kteach-core`
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type lib --crate-name kteach_core kteach-core/src/lib.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --document-private-items -C metadata=ff22800b5b139bb7 -L dependency=/opt/rustwide/target/debug/deps --extern cpal=/opt/rustwide/target/debug/deps/libcpal-6bab52cf99869aeb.rmeta --extern midir=/opt/rustwide/target/debug/deps/libmidir-d5cc920871e9330a.rmeta --extern ringbuf=/opt/rustwide/target/debug/deps/libringbuf-22c8e53c37548b46.rmeta --extern symphonia=/opt/rustwide/target/debug/deps/libsymphonia-1155003915eec80b.rmeta --extern synthesizer_io_core=/opt/rustwide/target/debug/deps/libsynthesizer_io_core-e70178bb8f33bfac.rmeta --extern time=/opt/rustwide/target/debug/deps/libtime-517afb1f9aa4be36.rmeta --extern wmidi=/opt/rustwide/target/debug/deps/libwmidi-ee00946057cd6d25.rmeta --cap-lints=warn --crate-version 0.1.0` (exit status: 1)
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `kteach-core` (lib) due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "b73606036de41f6febd6ff1a8ed4f09b4ac481f8c43c574e863797e2ce84f6fd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b73606036de41f6febd6ff1a8ed4f09b4ac481f8c43c574e863797e2ce84f6fd", kill_on_drop: false }`
[INFO] [stdout] b73606036de41f6febd6ff1a8ed4f09b4ac481f8c43c574e863797e2ce84f6fd
