[INFO] fetching crate prefixopt 0.4.0...
[INFO] testing prefixopt-0.4.0 against beta-2022-04-10 for beta-1.61-1
[INFO] extracting crate prefixopt 0.4.0 into /workspace/builds/worker-45/source
[INFO] validating manifest of crates.io crate prefixopt 0.4.0 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 prefixopt 0.4.0
[INFO] finished tweaking crates.io crate prefixopt 0.4.0
[INFO] tweaked toml for crates.io crate prefixopt 0.4.0 written to /workspace/builds/worker-45/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-45/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-45/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] c6aa83a3bdff9cfaa9071f722a0e91373b4760fdff1019d5d88cfb350bdb9e2b
[INFO] running `Command { std: "docker" "start" "-a" "c6aa83a3bdff9cfaa9071f722a0e91373b4760fdff1019d5d88cfb350bdb9e2b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "c6aa83a3bdff9cfaa9071f722a0e91373b4760fdff1019d5d88cfb350bdb9e2b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c6aa83a3bdff9cfaa9071f722a0e91373b4760fdff1019d5d88cfb350bdb9e2b", kill_on_drop: false }`
[INFO] [stdout] c6aa83a3bdff9cfaa9071f722a0e91373b4760fdff1019d5d88cfb350bdb9e2b
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-45/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-45/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] 1cfb3342b5fef12b5e9bc6551ab22ed63cc4cbfac98a3204f23bf78be3c2c695
[INFO] running `Command { std: "docker" "start" "-a" "1cfb3342b5fef12b5e9bc6551ab22ed63cc4cbfac98a3204f23bf78be3c2c695", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling libc v0.2.123
[INFO] [stderr]    Compiling scopeguard v0.2.0
[INFO] [stderr]    Compiling map_in_place v0.1.0
[INFO] [stderr]    Compiling atty v0.2.14
[INFO] [stderr]    Compiling clap v2.34.0
[INFO] [stderr]    Compiling prefixopt v0.4.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/parsable.rs:56:42
[INFO] [stdout]    |
[INFO] [stdout] 56 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[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] 56 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 56 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/parsable.rs:80:42
[INFO] [stdout]    |
[INFO] [stdout] 80 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 80 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 80 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/parsable.rs:98:42
[INFO] [stdout]    |
[INFO] [stdout] 98 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 98 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 98 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/core.rs:15:42
[INFO] [stdout]    |
[INFO] [stdout] 15 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 15 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self;
[INFO] [stdout] 15 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self;
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/std_impl.rs:13:42
[INFO] [stdout]    |
[INFO] [stdout] 13 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 13 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 13 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/std_impl.rs:39:42
[INFO] [stdout]    |
[INFO] [stdout] 39 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 39 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 39 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]  --> src/core.rs:9:69
[INFO] [stdout]   |
[INFO] [stdout] 9 |         Self::Container::concat_prefix(&ConcatRef::from(&prefix as &Display))
[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] 9 -         Self::Container::concat_prefix(&ConcatRef::from(&prefix as &Display))
[INFO] [stdout] 9 +         Self::Container::concat_prefix(&ConcatRef::from(&prefix as &dyn Display))
[INFO] [stdout]   | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> bin/example_1.rs:53:42
[INFO] [stdout]    |
[INFO] [stdout] 53 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[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] 53 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 53 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> bin/example_1.rs:68:42
[INFO] [stdout]    |
[INFO] [stdout] 68 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 68 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 68 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 20.80s
[INFO] running `Command { std: "docker" "inspect" "1cfb3342b5fef12b5e9bc6551ab22ed63cc4cbfac98a3204f23bf78be3c2c695", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1cfb3342b5fef12b5e9bc6551ab22ed63cc4cbfac98a3204f23bf78be3c2c695", kill_on_drop: false }`
[INFO] [stdout] 1cfb3342b5fef12b5e9bc6551ab22ed63cc4cbfac98a3204f23bf78be3c2c695
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-45/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-45/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" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 4996ede46cc13bee44c06b3eaf3221d266f3b72b779f2b24f850c4bad8bfeb29
[INFO] running `Command { std: "docker" "start" "-a" "4996ede46cc13bee44c06b3eaf3221d266f3b72b779f2b24f850c4bad8bfeb29", kill_on_drop: false }`
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/parsable.rs:56:42
[INFO] [stdout]    |
[INFO] [stdout] 56 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[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] 56 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 56 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/parsable.rs:80:42
[INFO] [stdout]    |
[INFO] [stdout] 80 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 80 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 80 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/parsable.rs:98:42
[INFO] [stdout]    |
[INFO] [stdout] 98 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 98 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 98 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/core.rs:15:42
[INFO] [stdout]    |
[INFO] [stdout] 15 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 15 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self;
[INFO] [stdout] 15 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self;
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling prefixopt v0.4.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/std_impl.rs:13:42
[INFO] [stdout]    |
[INFO] [stdout] 13 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 13 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 13 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/std_impl.rs:39:42
[INFO] [stdout]    |
[INFO] [stdout] 39 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 39 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 39 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]  --> src/core.rs:9:69
[INFO] [stdout]   |
[INFO] [stdout] 9 |         Self::Container::concat_prefix(&ConcatRef::from(&prefix as &Display))
[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] 9 -         Self::Container::concat_prefix(&ConcatRef::from(&prefix as &Display))
[INFO] [stdout] 9 +         Self::Container::concat_prefix(&ConcatRef::from(&prefix as &dyn Display))
[INFO] [stdout]   | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> bin/example_1.rs:53:42
[INFO] [stdout]    |
[INFO] [stdout] 53 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[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] 53 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 53 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> bin/example_1.rs:68:42
[INFO] [stdout]    |
[INFO] [stdout] 68 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 68 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 68 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> bin/example_1.rs:53:42
[INFO] [stdout]    |
[INFO] [stdout] 53 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[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] 53 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 53 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> bin/example_1.rs:68:42
[INFO] [stdout]    |
[INFO] [stdout] 68 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 68 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 68 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/parsable.rs:56:42
[INFO] [stdout]    |
[INFO] [stdout] 56 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[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] 56 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 56 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/parsable.rs:80:42
[INFO] [stdout]    |
[INFO] [stdout] 80 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 80 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 80 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/parsable.rs:98:42
[INFO] [stdout]    |
[INFO] [stdout] 98 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 98 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 98 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/core.rs:15:42
[INFO] [stdout]    |
[INFO] [stdout] 15 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 15 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self;
[INFO] [stdout] 15 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self;
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/std_impl.rs:13:42
[INFO] [stdout]    |
[INFO] [stdout] 13 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 13 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 13 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/std_impl.rs:39:42
[INFO] [stdout]    |
[INFO] [stdout] 39 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> 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] 39 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stdout] 39 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]  --> src/core.rs:9:69
[INFO] [stdout]   |
[INFO] [stdout] 9 |         Self::Container::concat_prefix(&ConcatRef::from(&prefix as &Display))
[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] 9 -         Self::Container::concat_prefix(&ConcatRef::from(&prefix as &Display))
[INFO] [stdout] 9 +         Self::Container::concat_prefix(&ConcatRef::from(&prefix as &dyn Display))
[INFO] [stdout]   | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 1.26s
[INFO] [stderr]   Executable unittests src/lib.rs (/opt/rustwide/target/debug/deps/prefixopt-d551fe3c70eac5a1)
[INFO] [stderr]   Executable unittests bin/example_1.rs (/opt/rustwide/target/debug/deps/example_1-9a87fa61024e0199)
[INFO] [stderr]   Executable tests/stdlib.rs (/opt/rustwide/target/debug/deps/stdlib-c0ae56d518db5cfb)
[INFO] running `Command { std: "docker" "inspect" "4996ede46cc13bee44c06b3eaf3221d266f3b72b779f2b24f850c4bad8bfeb29", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "4996ede46cc13bee44c06b3eaf3221d266f3b72b779f2b24f850c4bad8bfeb29", kill_on_drop: false }`
[INFO] [stdout] 4996ede46cc13bee44c06b3eaf3221d266f3b72b779f2b24f850c4bad8bfeb29
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-45/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-45/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" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] bc3488e5c532f09e76477649dc9fefc881e810aa0790acef71490a02c082d9cb
[INFO] running `Command { std: "docker" "start" "-a" "bc3488e5c532f09e76477649dc9fefc881e810aa0790acef71490a02c082d9cb", kill_on_drop: false }`
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> src/parsable.rs:56:42
[INFO] [stderr]    |
[INFO] [stderr] 56 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr]    |                                          ^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 56 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr] 56 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> src/parsable.rs:80:42
[INFO] [stderr]    |
[INFO] [stderr] 80 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr]    |                                          ^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 80 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr] 80 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> src/parsable.rs:98:42
[INFO] [stderr]    |
[INFO] [stderr] 98 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr]    |                                          ^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 98 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr] 98 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> src/core.rs:15:42
[INFO] [stderr]    |
[INFO] [stderr] 15 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self;
[INFO] [stderr]    |                                          ^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 15 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self;
[INFO] [stderr] 15 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self;
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> src/std_impl.rs:13:42
[INFO] [stderr]    |
[INFO] [stderr] 13 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr]    |                                          ^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 13 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr] 13 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> src/std_impl.rs:39:42
[INFO] [stderr]    |
[INFO] [stderr] 39 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr]    |                                          ^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 39 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr] 39 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]  --> src/core.rs:9:69
[INFO] [stderr]   |
[INFO] [stderr] 9 |         Self::Container::concat_prefix(&ConcatRef::from(&prefix as &Display))
[INFO] [stderr]   |                                                                     ^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]   |
[INFO] [stderr] 9 -         Self::Container::concat_prefix(&ConcatRef::from(&prefix as &Display))
[INFO] [stderr] 9 +         Self::Container::concat_prefix(&ConcatRef::from(&prefix as &dyn Display))
[INFO] [stderr]   | 
[INFO] [stderr] 
[INFO] [stderr] warning: `prefixopt` (lib) generated 7 warnings
[INFO] [stderr] warning: `prefixopt` (lib test) generated 7 warnings (7 duplicates)
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> bin/example_1.rs:53:42
[INFO] [stderr]    |
[INFO] [stderr] 53 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr]    |                                          ^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 53 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr] 53 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> bin/example_1.rs:68:42
[INFO] [stderr]    |
[INFO] [stderr] 68 |     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr]    |                                          ^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 68 -     fn concat_prefix(prefix: &ConcatRef<&Display>) -> Self {
[INFO] [stderr] 68 +     fn concat_prefix(prefix: &ConcatRef<&dyn Display>) -> Self {
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: `prefixopt` (bin "example_1" test) generated 2 warnings
[INFO] [stderr] warning: `prefixopt` (bin "example_1") generated 2 warnings (2 duplicates)
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.05s
[INFO] [stderr]      Running unittests src/lib.rs (/opt/rustwide/target/debug/deps/prefixopt-d551fe3c70eac5a1)
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stderr]      Running unittests bin/example_1.rs (/opt/rustwide/target/debug/deps/example_1-9a87fa61024e0199)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] [stderr]      Running tests/stdlib.rs (/opt/rustwide/target/debug/deps/stdlib-c0ae56d518db5cfb)
[INFO] [stdout] 
[INFO] [stdout] running 4 tests
[INFO] [stdout] test test_box_no_opt ... ok
[INFO] [stdout] test test_option_none ... ok
[INFO] [stdout] test test_box ... ok
[INFO] [stdout] test test_option_some ... ok
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 4 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] [stderr]    Doc-tests prefixopt
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "bc3488e5c532f09e76477649dc9fefc881e810aa0790acef71490a02c082d9cb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "bc3488e5c532f09e76477649dc9fefc881e810aa0790acef71490a02c082d9cb", kill_on_drop: false }`
[INFO] [stdout] bc3488e5c532f09e76477649dc9fefc881e810aa0790acef71490a02c082d9cb