[INFO] fetching crate png2aa 0.1.2...
[INFO] testing png2aa-0.1.2 against 1.75.0 for beta-1.76-1
[INFO] extracting crate png2aa 0.1.2 into /workspace/builds/worker-2-tc1/source
[INFO] validating manifest of crates.io crate png2aa 0.1.2 on toolchain 1.75.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.75.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate png2aa 0.1.2
[INFO] finished tweaking crates.io crate png2aa 0.1.2
[INFO] tweaked toml for crates.io crate png2aa 0.1.2 written to /workspace/builds/worker-2-tc1/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.75.0" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Updating crates.io index
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.75.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded gif v0.9.2
[INFO] [stderr]   Downloaded png v0.11.0
[INFO] [stderr]   Downloaded inflate v0.3.4
[INFO] [stderr]   Downloaded image v0.18.0
[INFO] [stderr]   Downloaded string-error v0.1.0
[INFO] [stderr]   Downloaded ndarray v0.10.14
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+1.75.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] f0b4954c613f89610005f6588647450a960cfa362a9538a245142a72604a6d36
[INFO] running `Command { std: "docker" "start" "-a" "f0b4954c613f89610005f6588647450a960cfa362a9538a245142a72604a6d36", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "f0b4954c613f89610005f6588647450a960cfa362a9538a245142a72604a6d36", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f0b4954c613f89610005f6588647450a960cfa362a9538a245142a72604a6d36", kill_on_drop: false }`
[INFO] [stdout] f0b4954c613f89610005f6588647450a960cfa362a9538a245142a72604a6d36
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+1.75.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 210c4968d0ec768d364be0f83b76b9b856437ba727cf38cb1c8fe2c37fac6cf6
[INFO] running `Command { std: "docker" "start" "-a" "210c4968d0ec768d364be0f83b76b9b856437ba727cf38cb1c8fe2c37fac6cf6", kill_on_drop: false }`
[INFO] [stderr]    Compiling num-traits v0.2.17
[INFO] [stderr]    Compiling num-integer v0.1.45
[INFO] [stderr]    Compiling either v1.9.0
[INFO] [stderr]    Compiling num-iter v0.1.43
[INFO] [stderr]    Compiling byteorder v1.5.0
[INFO] [stderr]    Compiling adler32 v1.2.0
[INFO] [stderr]    Compiling matrixmultiply v0.1.15
[INFO] [stderr]    Compiling bitflags v1.3.2
[INFO] [stderr]    Compiling lzw v0.10.0
[INFO] [stderr]    Compiling rawpointer v0.1.0
[INFO] [stderr]    Compiling ndarray v0.10.14
[INFO] [stderr]    Compiling color_quant v1.1.0
[INFO] [stderr]    Compiling safemem v0.2.0
[INFO] [stderr]    Compiling scoped_threadpool v0.1.9
[INFO] [stderr]    Compiling getopts v0.2.21
[INFO] [stderr]    Compiling string-error v0.1.0
[INFO] [stderr]    Compiling inflate v0.3.4
[INFO] [stderr]    Compiling deflate v0.7.20
[INFO] [stderr]    Compiling base64 v0.6.0
[INFO] [stderr]    Compiling gif v0.9.2
[INFO] [stderr]    Compiling rayon v1.8.0
[INFO] [stderr]    Compiling itertools v0.7.11
[INFO] [stderr]    Compiling num-traits v0.1.43
[INFO] [stderr]    Compiling num-complex v0.1.43
[INFO] [stderr]    Compiling enum_primitive v0.1.1
[INFO] [stderr]    Compiling num-rational v0.1.42
[INFO] [stderr]    Compiling png v0.11.0
[INFO] [stderr]    Compiling jpeg-decoder v0.1.22
[INFO] [stderr]    Compiling image v0.18.0
[INFO] [stderr]    Compiling png2aa v0.1.2 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused `#[macro_use]` import
[INFO] [stdout]  --> src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #[macro_use] extern crate ndarray;
[INFO] [stdout]   | ^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/utils.rs:21:33
[INFO] [stdout]    |
[INFO] [stdout] 21 | pub fn read_png(image_file: Box<Read>) -> Result<Array3<f32>, Box<Error>> {
[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]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 21 | pub fn read_png(image_file: Box<dyn Read>) -> Result<Array3<f32>, Box<Error>> {
[INFO] [stdout]    |                                 +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/utils.rs:21:67
[INFO] [stdout]    |
[INFO] [stdout] 21 | pub fn read_png(image_file: Box<Read>) -> Result<Array3<f32>, Box<Error>> {
[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] 21 | pub fn read_png(image_file: Box<Read>) -> Result<Array3<f32>, Box<dyn Error>> {
[INFO] [stdout]    |                                                                   +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/utils.rs:38:44
[INFO] [stdout]    |
[INFO] [stdout] 38 | pub fn write_grayscale_png(image_file: Box<Write>, img: &Array2<f32>) -> Result<(), Box<Error>> {
[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] 38 | pub fn write_grayscale_png(image_file: Box<dyn Write>, img: &Array2<f32>) -> Result<(), Box<Error>> {
[INFO] [stdout]    |                                            +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/utils.rs:38:89
[INFO] [stdout]    |
[INFO] [stdout] 38 | pub fn write_grayscale_png(image_file: Box<Write>, img: &Array2<f32>) -> Result<(), Box<Error>> {
[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] 38 | pub fn write_grayscale_png(image_file: Box<Write>, img: &Array2<f32>) -> Result<(), Box<dyn Error>> {
[INFO] [stdout]    |                                                                                         +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 5 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/cli.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(slice_patterns)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove the attribute
[INFO] [stdout]   |
[INFO] [stdout]   = help: the feature `slice_patterns` has been stable since `1.42.0` and no longer requires an attribute to enable
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the feature `slice_patterns` has been stable since 1.42.0 and no longer requires an attribute to enable
[INFO] [stdout]  --> src/cli.rs:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(slice_patterns)]
[INFO] [stdout]   |            ^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(stable_features)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error; 1 warning 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 `png2aa` (bin "png2aa") due to 2 previous errors; 1 warning emitted
[INFO] running `Command { std: "docker" "inspect" "210c4968d0ec768d364be0f83b76b9b856437ba727cf38cb1c8fe2c37fac6cf6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "210c4968d0ec768d364be0f83b76b9b856437ba727cf38cb1c8fe2c37fac6cf6", kill_on_drop: false }`
[INFO] [stdout] 210c4968d0ec768d364be0f83b76b9b856437ba727cf38cb1c8fe2c37fac6cf6
[INFO] testing png2aa-0.1.2 against beta-2023-12-22 for beta-1.76-1
[INFO] extracting crate png2aa 0.1.2 into /workspace/builds/worker-2-tc2/source
[INFO] validating manifest of crates.io crate png2aa 0.1.2 on toolchain beta-2023-12-22
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2023-12-22" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate png2aa 0.1.2
[INFO] finished tweaking crates.io crate png2aa 0.1.2
[INFO] tweaked toml for crates.io crate png2aa 0.1.2 written to /workspace/builds/worker-2-tc2/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2023-12-22" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2023-12-22" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2023-12-22" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 5d9e965e385e1c62186a00b4c21156bdb7a8f6381f12020ef831586a0ec922ae
[INFO] running `Command { std: "docker" "start" "-a" "5d9e965e385e1c62186a00b4c21156bdb7a8f6381f12020ef831586a0ec922ae", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "5d9e965e385e1c62186a00b4c21156bdb7a8f6381f12020ef831586a0ec922ae", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5d9e965e385e1c62186a00b4c21156bdb7a8f6381f12020ef831586a0ec922ae", kill_on_drop: false }`
[INFO] [stdout] 5d9e965e385e1c62186a00b4c21156bdb7a8f6381f12020ef831586a0ec922ae
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2023-12-22" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] da446d5ffefc847c8cd550a0944609a6d1ccffd16667b3d6d50efdae5cc7057b
[INFO] running `Command { std: "docker" "start" "-a" "da446d5ffefc847c8cd550a0944609a6d1ccffd16667b3d6d50efdae5cc7057b", kill_on_drop: false }`
[INFO] [stderr]    Compiling num-traits v0.2.17
[INFO] [stderr]    Compiling num-integer v0.1.45
[INFO] [stderr]    Compiling either v1.9.0
[INFO] [stderr]    Compiling num-iter v0.1.43
[INFO] [stderr]    Compiling byteorder v1.5.0
[INFO] [stderr]    Compiling adler32 v1.2.0
[INFO] [stderr]    Compiling matrixmultiply v0.1.15
[INFO] [stderr]    Compiling rawpointer v0.1.0
[INFO] [stderr]    Compiling ndarray v0.10.14
[INFO] [stderr]    Compiling lzw v0.10.0
[INFO] [stderr]    Compiling color_quant v1.1.0
[INFO] [stderr]    Compiling bitflags v1.3.2
[INFO] [stderr]    Compiling scoped_threadpool v0.1.9
[INFO] [stderr]    Compiling safemem v0.2.0
[INFO] [stderr]    Compiling getopts v0.2.21
[INFO] [stderr]    Compiling string-error v0.1.0
[INFO] [stderr]    Compiling inflate v0.3.4
[INFO] [stderr]    Compiling rayon v1.8.0
[INFO] [stderr]    Compiling itertools v0.7.11
[INFO] [stderr]    Compiling gif v0.9.2
[INFO] [stderr]    Compiling deflate v0.7.20
[INFO] [stderr]    Compiling base64 v0.6.0
[INFO] [stderr]    Compiling num-traits v0.1.43
[INFO] [stderr]    Compiling num-complex v0.1.43
[INFO] [stderr]    Compiling enum_primitive v0.1.1
[INFO] [stderr]    Compiling num-rational v0.1.42
[INFO] [stderr]    Compiling png v0.11.0
[INFO] [stderr]    Compiling jpeg-decoder v0.1.22
[INFO] [stderr]    Compiling image v0.18.0
[INFO] [stderr]    Compiling png2aa v0.1.2 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused `#[macro_use]` import
[INFO] [stdout]  --> src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #[macro_use] extern crate ndarray;
[INFO] [stdout]   | ^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/utils.rs:21:33
[INFO] [stdout]    |
[INFO] [stdout] 21 | pub fn read_png(image_file: Box<Read>) -> Result<Array3<f32>, Box<Error>> {
[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]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 21 | pub fn read_png(image_file: Box<dyn Read>) -> Result<Array3<f32>, Box<Error>> {
[INFO] [stdout]    |                                 +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/utils.rs:21:67
[INFO] [stdout]    |
[INFO] [stdout] 21 | pub fn read_png(image_file: Box<Read>) -> Result<Array3<f32>, Box<Error>> {
[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] 21 | pub fn read_png(image_file: Box<Read>) -> Result<Array3<f32>, Box<dyn Error>> {
[INFO] [stdout]    |                                                                   +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/utils.rs:38:44
[INFO] [stdout]    |
[INFO] [stdout] 38 | pub fn write_grayscale_png(image_file: Box<Write>, img: &Array2<f32>) -> Result<(), Box<Error>> {
[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] 38 | pub fn write_grayscale_png(image_file: Box<dyn Write>, img: &Array2<f32>) -> Result<(), Box<Error>> {
[INFO] [stdout]    |                                            +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/utils.rs:38:89
[INFO] [stdout]    |
[INFO] [stdout] 38 | pub fn write_grayscale_png(image_file: Box<Write>, img: &Array2<f32>) -> Result<(), Box<Error>> {
[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] 38 | pub fn write_grayscale_png(image_file: Box<Write>, img: &Array2<f32>) -> Result<(), Box<dyn Error>> {
[INFO] [stdout]    |                                                                                         +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 5 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/cli.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(slice_patterns)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove the attribute
[INFO] [stdout]   |
[INFO] [stdout]   = help: the feature `slice_patterns` has been stable since `1.42.0` and no longer requires an attribute to enable
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the feature `slice_patterns` has been stable since 1.42.0 and no longer requires an attribute to enable
[INFO] [stdout]  --> src/cli.rs:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(slice_patterns)]
[INFO] [stdout]   |            ^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(stable_features)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error; 1 warning 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 `png2aa` (bin "png2aa") due to 2 previous errors; 1 warning emitted
[INFO] running `Command { std: "docker" "inspect" "da446d5ffefc847c8cd550a0944609a6d1ccffd16667b3d6d50efdae5cc7057b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "da446d5ffefc847c8cd550a0944609a6d1ccffd16667b3d6d50efdae5cc7057b", kill_on_drop: false }`
[INFO] [stdout] da446d5ffefc847c8cd550a0944609a6d1ccffd16667b3d6d50efdae5cc7057b
