[INFO] fetching crate nibble 0.1.0...
[INFO] testing nibble-0.1.0 against beta-2022-04-10 for beta-1.61-1
[INFO] extracting crate nibble 0.1.0 into /workspace/builds/worker-26/source
[INFO] validating manifest of crates.io crate nibble 0.1.0 on toolchain beta-2022-04-10
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2022-04-10" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate nibble 0.1.0
[INFO] finished tweaking crates.io crate nibble 0.1.0
[INFO] tweaked toml for crates.io crate nibble 0.1.0 written to /workspace/builds/worker-26/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2022-04-10" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2022-04-10" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-26/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-26/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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2022-04-10" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 63dc8671c861695f401c34f2a38a55be4333f1f04a2df6af867e062f838470d5
[INFO] running `Command { std: "docker" "start" "-a" "63dc8671c861695f401c34f2a38a55be4333f1f04a2df6af867e062f838470d5", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "63dc8671c861695f401c34f2a38a55be4333f1f04a2df6af867e062f838470d5", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "63dc8671c861695f401c34f2a38a55be4333f1f04a2df6af867e062f838470d5", kill_on_drop: false }`
[INFO] [stdout] 63dc8671c861695f401c34f2a38a55be4333f1f04a2df6af867e062f838470d5
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-26/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-26/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" "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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2022-04-10" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 7fd5dc5388639577f076c68af24475050e01b76f61c1bcd8f005156984b4d6fc
[INFO] running `Command { std: "docker" "start" "-a" "7fd5dc5388639577f076c68af24475050e01b76f61c1bcd8f005156984b4d6fc", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling arrayvec v0.4.12
[INFO] [stderr]    Compiling nodrop v0.1.14
[INFO] [stderr]    Compiling num-traits v0.2.14
[INFO] [stderr]    Compiling num-traits v0.1.43
[INFO] [stderr]    Compiling nibble v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]   --> src/base.rs:87:17
[INFO] [stdout]    |
[INFO] [stdout] 87 |             b'0'...b'9' => Some(Self::from_lo(b - b'0')),
[INFO] [stdout]    |                 ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(ellipsis_inclusive_range_patterns)]` on by default
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]   --> src/base.rs:88:17
[INFO] [stdout]    |
[INFO] [stdout] 88 |             b'A'...b'F' => Some(Self::from_lo(b - b'A' + 0xA)),
[INFO] [stdout]    |                 ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]   --> src/base.rs:89:17
[INFO] [stdout]    |
[INFO] [stdout] 89 |             b'a'...b'f' => Some(Self::from_lo(b - b'a' + 0xa)),
[INFO] [stdout]    |                 ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]   --> src/base.rs:98:16
[INFO] [stdout]    |
[INFO] [stdout] 98 |             0x0...0x9 => b'0' + val,
[INFO] [stdout]    |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]   --> src/base.rs:99:16
[INFO] [stdout]    |
[INFO] [stdout] 99 |             0xa...0xf => b'a' + val - 0xa,
[INFO] [stdout]    |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/base.rs:108:16
[INFO] [stdout]     |
[INFO] [stdout] 108 |             0x0...0x9 => b'0' + val,
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/base.rs:109:16
[INFO] [stdout]     |
[INFO] [stdout] 109 |             0xA...0xF => b'A' + val - 0xA,
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/base.rs:120:16
[INFO] [stdout]     |
[INFO] [stdout] 120 |             '0'...'9' => Some(Self::from_lo(u32::from(c) as u8 - b'0')),
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/base.rs:121:16
[INFO] [stdout]     |
[INFO] [stdout] 121 |             'A'...'F' => Some(Self::from_lo(u32::from(c) as u8 - b'A' + 0xA)),
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: `...` range patterns are deprecated
[INFO] [stdout]    --> src/base.rs:122:16
[INFO] [stdout]     |
[INFO] [stdout] 122 |             'a'...'f' => Some(Self::from_lo(u32::from(c) as u8 - b'a' + 0xa)),
[INFO] [stdout]     |                ^^^ help: use `..=` for an inclusive range
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:227:20
[INFO] [stdout]     |
[INFO] [stdout] 227 |     hi: Option<&'a u4>,
[INFO] [stdout]     |                    ^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 227 -     hi: Option<&'a u4>,
[INFO] [stdout] 227 +     hi: Option<&'a dyn u4>,
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:228:20
[INFO] [stdout]     |
[INFO] [stdout] 228 |     lo: Option<&'a u4>,
[INFO] [stdout]     |                    ^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 228 -     lo: Option<&'a u4>,
[INFO] [stdout] 228 +     lo: Option<&'a dyn u4>,
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:253:20
[INFO] [stdout]     |
[INFO] [stdout] 253 |     hi: Option<&'a U4Cell>,
[INFO] [stdout]     |                    ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 253 -     hi: Option<&'a U4Cell>,
[INFO] [stdout] 253 +     hi: Option<&'a dyn U4Cell>,
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:254:20
[INFO] [stdout]     |
[INFO] [stdout] 254 |     lo: Option<&'a U4Cell>,
[INFO] [stdout]     |                    ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 254 -     lo: Option<&'a U4Cell>,
[INFO] [stdout] 254 +     lo: Option<&'a dyn U4Cell>,
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/lib.rs:6:12
[INFO] [stdout]   |
[INFO] [stdout] 6 | #![feature(try_from)]
[INFO] [stdout]   |            ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/lib.rs:8:12
[INFO] [stdout]   |
[INFO] [stdout] 8 | #![feature(trace_macros)]
[INFO] [stdout]   |            ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the feature `try_from` has been stable since 1.34.0 and no longer requires an attribute to enable
[INFO] [stdout]  --> src/lib.rs:6:12
[INFO] [stdout]   |
[INFO] [stdout] 6 | #![feature(try_from)]
[INFO] [stdout]   |            ^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(stable_features)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/common.rs:85:62
[INFO] [stdout]    |
[INFO] [stdout] 85 | pub(crate) fn get_nib_ref(slice: &[u4x2], nibidx: usize) -> &u4 {
[INFO] [stdout]    |                                                              ^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 85 - pub(crate) fn get_nib_ref(slice: &[u4x2], nibidx: usize) -> &u4 {
[INFO] [stdout] 85 + pub(crate) fn get_nib_ref(slice: &[u4x2], nibidx: usize) -> &dyn u4 {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/common.rs:94:66
[INFO] [stdout]    |
[INFO] [stdout] 94 | pub(crate) fn get_nib_mut(slice: &mut [u4x2], nibidx: usize) -> &U4Cell {
[INFO] [stdout]    |                                                                  ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 94 - pub(crate) fn get_nib_mut(slice: &mut [u4x2], nibidx: usize) -> &U4Cell {
[INFO] [stdout] 94 + pub(crate) fn get_nib_mut(slice: &mut [u4x2], nibidx: usize) -> &dyn U4Cell {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/array.rs:196:50
[INFO] [stdout]     |
[INFO] [stdout] 196 | impl<'a, A: Array<Item = u4x2>> FromIterator<&'a u4> for NibArrayVec<A> {
[INFO] [stdout]     |                                                  ^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 196 - impl<'a, A: Array<Item = u4x2>> FromIterator<&'a u4> for NibArrayVec<A> {
[INFO] [stdout] 196 + impl<'a, A: Array<Item = u4x2>> FromIterator<&'a dyn u4> for NibArrayVec<A> {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/array.rs:217:44
[INFO] [stdout]     |
[INFO] [stdout] 217 | impl<'a, A: Array<Item = u4x2>> Extend<&'a u4> for NibArrayVec<A> {
[INFO] [stdout]     |                                            ^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 217 - impl<'a, A: Array<Item = u4x2>> Extend<&'a u4> for NibArrayVec<A> {
[INFO] [stdout] 217 + impl<'a, A: Array<Item = u4x2>> Extend<&'a dyn u4> for NibArrayVec<A> {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/array.rs:197:45
[INFO] [stdout]     |
[INFO] [stdout] 197 |     fn from_iter<I: IntoIterator<Item = &'a u4>>(iter: I) -> Self {
[INFO] [stdout]     |                                             ^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 197 -     fn from_iter<I: IntoIterator<Item = &'a u4>>(iter: I) -> Self {
[INFO] [stdout] 197 +     fn from_iter<I: IntoIterator<Item = &'a dyn u4>>(iter: I) -> Self {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/array.rs:218:42
[INFO] [stdout]     |
[INFO] [stdout] 218 |     fn extend<I: IntoIterator<Item = &'a u4>>(&mut self, iter: I) {
[INFO] [stdout]     |                                          ^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 218 -     fn extend<I: IntoIterator<Item = &'a u4>>(&mut self, iter: I) {
[INFO] [stdout] 218 +     fn extend<I: IntoIterator<Item = &'a dyn u4>>(&mut self, iter: I) {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/iter.rs:141:21
[INFO] [stdout]     |
[INFO] [stdout] 141 |     type Item = &'a u4;
[INFO] [stdout]     |                     ^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 141 -     type Item = &'a u4;
[INFO] [stdout] 141 +     type Item = &'a dyn u4;
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/iter.rs:142:38
[INFO] [stdout]     |
[INFO] [stdout] 142 |     fn next(&mut self) -> Option<&'a u4> {
[INFO] [stdout]     |                                      ^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 142 -     fn next(&mut self) -> Option<&'a u4> {
[INFO] [stdout] 142 +     fn next(&mut self) -> Option<&'a dyn u4> {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/iter.rs:163:43
[INFO] [stdout]     |
[INFO] [stdout] 163 |     fn next_back(&mut self) -> Option<&'a u4> {
[INFO] [stdout]     |                                           ^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 163 -     fn next_back(&mut self) -> Option<&'a u4> {
[INFO] [stdout] 163 +     fn next_back(&mut self) -> Option<&'a dyn u4> {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/iter.rs:212:21
[INFO] [stdout]     |
[INFO] [stdout] 212 |     type Item = &'a U4Cell;
[INFO] [stdout]     |                     ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 212 -     type Item = &'a U4Cell;
[INFO] [stdout] 212 +     type Item = &'a dyn U4Cell;
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/iter.rs:213:38
[INFO] [stdout]     |
[INFO] [stdout] 213 |     fn next(&mut self) -> Option<&'a U4Cell> {
[INFO] [stdout]     |                                      ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 213 -     fn next(&mut self) -> Option<&'a U4Cell> {
[INFO] [stdout] 213 +     fn next(&mut self) -> Option<&'a dyn U4Cell> {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/iter.rs:234:43
[INFO] [stdout]     |
[INFO] [stdout] 234 |     fn next_back(&mut self) -> Option<&'a U4Cell> {
[INFO] [stdout]     |                                           ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 234 -     fn next_back(&mut self) -> Option<&'a U4Cell> {
[INFO] [stdout] 234 +     fn next_back(&mut self) -> Option<&'a dyn U4Cell> {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:296:26
[INFO] [stdout]     |
[INFO] [stdout] 296 |     fn swap(&self, nib: &U4Cell);
[INFO] [stdout]     |                          ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 296 -     fn swap(&self, nib: &U4Cell);
[INFO] [stdout] 296 +     fn swap(&self, nib: &dyn U4Cell);
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:231:21
[INFO] [stdout]     |
[INFO] [stdout] 231 |     type Item = &'a u4;
[INFO] [stdout]     |                     ^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 231 -     type Item = &'a u4;
[INFO] [stdout] 231 +     type Item = &'a dyn u4;
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:232:38
[INFO] [stdout]     |
[INFO] [stdout] 232 |     fn next(&mut self) -> Option<&'a u4> {
[INFO] [stdout]     |                                      ^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 232 -     fn next(&mut self) -> Option<&'a u4> {
[INFO] [stdout] 232 +     fn next(&mut self) -> Option<&'a dyn u4> {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:240:43
[INFO] [stdout]     |
[INFO] [stdout] 240 |     fn next_back(&mut self) -> Option<&'a u4> {
[INFO] [stdout]     |                                           ^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 240 -     fn next_back(&mut self) -> Option<&'a u4> {
[INFO] [stdout] 240 +     fn next_back(&mut self) -> Option<&'a dyn u4> {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:257:21
[INFO] [stdout]     |
[INFO] [stdout] 257 |     type Item = &'a U4Cell;
[INFO] [stdout]     |                     ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 257 -     type Item = &'a U4Cell;
[INFO] [stdout] 257 +     type Item = &'a dyn U4Cell;
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:258:38
[INFO] [stdout]     |
[INFO] [stdout] 258 |     fn next(&mut self) -> Option<&'a U4Cell> {
[INFO] [stdout]     |                                      ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 258 -     fn next(&mut self) -> Option<&'a U4Cell> {
[INFO] [stdout] 258 +     fn next(&mut self) -> Option<&'a dyn U4Cell> {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:266:43
[INFO] [stdout]     |
[INFO] [stdout] 266 |     fn next_back(&mut self) -> Option<&'a U4Cell> {
[INFO] [stdout]     |                                           ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 266 -     fn next_back(&mut self) -> Option<&'a U4Cell> {
[INFO] [stdout] 266 +     fn next_back(&mut self) -> Option<&'a dyn U4Cell> {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:327:26
[INFO] [stdout]     |
[INFO] [stdout] 327 |     fn swap(&self, nib: &U4Cell) {
[INFO] [stdout]     |                          ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 327 -     fn swap(&self, nib: &U4Cell) {
[INFO] [stdout] 327 +     fn swap(&self, nib: &dyn U4Cell) {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/pair.rs:367:26
[INFO] [stdout]     |
[INFO] [stdout] 367 |     fn swap(&self, nib: &U4Cell) {
[INFO] [stdout]     |                          ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 367 -     fn swap(&self, nib: &U4Cell) {
[INFO] [stdout] 367 +     fn swap(&self, nib: &dyn U4Cell) {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/slice.rs:66:35
[INFO] [stdout]    |
[INFO] [stdout] 66 |     fn get(&self, idx: usize) -> &u4 {
[INFO] [stdout]    |                                   ^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 66 -     fn get(&self, idx: usize) -> &u4 {
[INFO] [stdout] 66 +     fn get(&self, idx: usize) -> &dyn u4 {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/slice.rs:160:43
[INFO] [stdout]     |
[INFO] [stdout] 160 |     fn get_mut(&mut self, idx: usize) -> &U4Cell {
[INFO] [stdout]     |                                           ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 160 -     fn get_mut(&mut self, idx: usize) -> &U4Cell {
[INFO] [stdout] 160 +     fn get_mut(&mut self, idx: usize) -> &dyn U4Cell {
[INFO] [stdout]     | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 previous errors; 38 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `nibble` due to 3 previous errors; 38 warnings emitted
[INFO] running `Command { std: "docker" "inspect" "7fd5dc5388639577f076c68af24475050e01b76f61c1bcd8f005156984b4d6fc", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7fd5dc5388639577f076c68af24475050e01b76f61c1bcd8f005156984b4d6fc", kill_on_drop: false }`
[INFO] [stdout] 7fd5dc5388639577f076c68af24475050e01b76f61c1bcd8f005156984b4d6fc