[INFO] cloning repository https://github.com/panzi/rust-json-builder [INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/panzi/rust-json-builder" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fpanzi%2Frust-json-builder", kill_on_drop: false }` [INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fpanzi%2Frust-json-builder'... [INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }` [INFO] [stdout] 55a32321d40ad0f6ff02f1fba733afca27c31991 [INFO] testing panzi/rust-json-builder against 1.59.0 for beta-1.60-1 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fpanzi%2Frust-json-builder" "/workspace/builds/worker-29/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-29/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/panzi/rust-json-builder on toolchain 1.59.0 [INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.59.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/panzi/rust-json-builder [INFO] finished tweaking git repo https://github.com/panzi/rust-json-builder [INFO] tweaked toml for git repo https://github.com/panzi/rust-json-builder written to /workspace/builds/worker-29/source/Cargo.toml [INFO] crate git repo https://github.com/panzi/rust-json-builder already has a lockfile, it will not be regenerated [INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.59.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-29/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-29/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@sha256:0cd99ca24d8e8c98e67c542213511d985b8778b5bdcbb160e038429496686047" "/opt/rustwide/cargo-home/bin/cargo" "+1.59.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] 1c7a2a3e3b6732277827d232515e7273214d9cf1c69ecc3062a83d08be8123a3 [INFO] running `Command { std: "docker" "start" "-a" "1c7a2a3e3b6732277827d232515e7273214d9cf1c69ecc3062a83d08be8123a3", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "1c7a2a3e3b6732277827d232515e7273214d9cf1c69ecc3062a83d08be8123a3", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "1c7a2a3e3b6732277827d232515e7273214d9cf1c69ecc3062a83d08be8123a3", kill_on_drop: false }` [INFO] [stdout] 1c7a2a3e3b6732277827d232515e7273214d9cf1c69ecc3062a83d08be8123a3 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-29/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-29/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@sha256:0cd99ca24d8e8c98e67c542213511d985b8778b5bdcbb160e038429496686047" "/opt/rustwide/cargo-home/bin/cargo" "+1.59.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] 1b8083e9591497a380177d5f0258ec0356fcc71080885e72f338441fa813aeb5 [INFO] running `Command { std: "docker" "start" "-a" "1b8083e9591497a380177d5f0258ec0356fcc71080885e72f338441fa813aeb5", kill_on_drop: false }` [INFO] [stderr] Compiling json_builder v0.1.0 (/opt/rustwide/workdir) [INFO] [stdout] warning: unknown `doc` attribute `hide` [INFO] [stdout] --> src/json_builder.rs:510:7 [INFO] [stdout] | [INFO] [stdout] 510 | #[doc(hide)] [INFO] [stdout] | ^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(invalid_doc_attributes)]` on by default [INFO] [stdout] = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release! [INFO] [stdout] = note: for more information, see issue #82730 [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/json_builder.rs:365:27 [INFO] [stdout] | [INFO] [stdout] 365 | impl<'a> IntoJSON for &'a IntoJSON { [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 [INFO] [stdout] help: use `dyn` [INFO] [stdout] | [INFO] [stdout] 365 - impl<'a> IntoJSON for &'a IntoJSON { [INFO] [stdout] 365 + impl<'a> IntoJSON for &'a dyn IntoJSON { [INFO] [stdout] | [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/json_builder.rs:26:18 [INFO] [stdout] | [INFO] [stdout] 26 | writer: &'a mut Write, [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 [INFO] [stdout] help: use `dyn` [INFO] [stdout] | [INFO] [stdout] 26 - writer: &'a mut Write, [INFO] [stdout] 26 + writer: &'a mut dyn Write, [INFO] [stdout] | [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/json_builder.rs:66:42 [INFO] [stdout] | [INFO] [stdout] 66 | pub fn escape_json(s: &str, writer: &mut Write) -> std::io::Result<()> { [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 [INFO] [stdout] help: use `dyn` [INFO] [stdout] | [INFO] [stdout] 66 - pub fn escape_json(s: &str, writer: &mut Write) -> std::io::Result<()> { [INFO] [stdout] 66 + pub fn escape_json(s: &str, writer: &mut dyn Write) -> std::io::Result<()> { [INFO] [stdout] | [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/json_builder.rs:135:26 [INFO] [stdout] | [INFO] [stdout] 135 | pub fn new(writer: &mut Write) -> JSONBuilder { [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 [INFO] [stdout] help: use `dyn` [INFO] [stdout] | [INFO] [stdout] 135 - pub fn new(writer: &mut Write) -> JSONBuilder { [INFO] [stdout] 135 + pub fn new(writer: &mut dyn Write) -> JSONBuilder { [INFO] [stdout] | [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/json_builder.rs:144:33 [INFO] [stdout] | [INFO] [stdout] 144 | pub fn new_pretty(writer: &mut Write, indent_size: usize, tab_indent: bool) -> JSONBuilder { [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 [INFO] [stdout] help: use `dyn` [INFO] [stdout] | [INFO] [stdout] 144 - pub fn new_pretty(writer: &mut Write, indent_size: usize, tab_indent: bool) -> JSONBuilder { [INFO] [stdout] 144 + pub fn new_pretty(writer: &mut dyn Write, indent_size: usize, tab_indent: bool) -> JSONBuilder { [INFO] [stdout] | [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 6 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Finished dev [unoptimized + debuginfo] target(s) in 1.00s [INFO] running `Command { std: "docker" "inspect" "1b8083e9591497a380177d5f0258ec0356fcc71080885e72f338441fa813aeb5", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "1b8083e9591497a380177d5f0258ec0356fcc71080885e72f338441fa813aeb5", kill_on_drop: false }` [INFO] [stdout] 1b8083e9591497a380177d5f0258ec0356fcc71080885e72f338441fa813aeb5 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-29/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-29/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@sha256:0cd99ca24d8e8c98e67c542213511d985b8778b5bdcbb160e038429496686047" "/opt/rustwide/cargo-home/bin/cargo" "+1.59.0" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] 7dcecb983ff905d3cbf8eb99707cf5f50a59f7af88d2b8723b82129fc310cbd0 [INFO] running `Command { std: "docker" "start" "-a" "7dcecb983ff905d3cbf8eb99707cf5f50a59f7af88d2b8723b82129fc310cbd0", kill_on_drop: false }` [INFO] [stderr] Compiling json_builder v0.1.0 (/opt/rustwide/workdir) [INFO] [stdout] warning: unknown `doc` attribute `hide` [INFO] [stdout] --> src/json_builder.rs:510:7 [INFO] [stdout] | [INFO] [stdout] 510 | #[doc(hide)] [INFO] [stdout] | ^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(invalid_doc_attributes)]` on by default [INFO] [stdout] = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release! [INFO] [stdout] = note: for more information, see issue #82730 [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/json_builder.rs:365:27 [INFO] [stdout] | [INFO] [stdout] 365 | impl<'a> IntoJSON for &'a IntoJSON { [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 [INFO] [stdout] help: use `dyn` [INFO] [stdout] | [INFO] [stdout] 365 - impl<'a> IntoJSON for &'a IntoJSON { [INFO] [stdout] 365 + impl<'a> IntoJSON for &'a dyn IntoJSON { [INFO] [stdout] | [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/json_builder.rs:26:18 [INFO] [stdout] | [INFO] [stdout] 26 | writer: &'a mut Write, [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 [INFO] [stdout] help: use `dyn` [INFO] [stdout] | [INFO] [stdout] 26 - writer: &'a mut Write, [INFO] [stdout] 26 + writer: &'a mut dyn Write, [INFO] [stdout] | [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/json_builder.rs:66:42 [INFO] [stdout] | [INFO] [stdout] 66 | pub fn escape_json(s: &str, writer: &mut Write) -> std::io::Result<()> { [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 [INFO] [stdout] help: use `dyn` [INFO] [stdout] | [INFO] [stdout] 66 - pub fn escape_json(s: &str, writer: &mut Write) -> std::io::Result<()> { [INFO] [stdout] 66 + pub fn escape_json(s: &str, writer: &mut dyn Write) -> std::io::Result<()> { [INFO] [stdout] | [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/json_builder.rs:135:26 [INFO] [stdout] | [INFO] [stdout] 135 | pub fn new(writer: &mut Write) -> JSONBuilder { [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 [INFO] [stdout] help: use `dyn` [INFO] [stdout] | [INFO] [stdout] 135 - pub fn new(writer: &mut Write) -> JSONBuilder { [INFO] [stdout] 135 + pub fn new(writer: &mut dyn Write) -> JSONBuilder { [INFO] [stdout] | [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/json_builder.rs:144:33 [INFO] [stdout] | [INFO] [stdout] 144 | pub fn new_pretty(writer: &mut Write, indent_size: usize, tab_indent: bool) -> JSONBuilder { [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 [INFO] [stdout] help: use `dyn` [INFO] [stdout] | [INFO] [stdout] 144 - pub fn new_pretty(writer: &mut Write, indent_size: usize, tab_indent: bool) -> JSONBuilder { [INFO] [stdout] 144 + pub fn new_pretty(writer: &mut dyn Write, indent_size: usize, tab_indent: bool) -> JSONBuilder { [INFO] [stdout] | [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 6 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Finished test [unoptimized + debuginfo] target(s) in 0.59s [INFO] running `Command { std: "docker" "inspect" "7dcecb983ff905d3cbf8eb99707cf5f50a59f7af88d2b8723b82129fc310cbd0", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "7dcecb983ff905d3cbf8eb99707cf5f50a59f7af88d2b8723b82129fc310cbd0", kill_on_drop: false }` [INFO] [stdout] 7dcecb983ff905d3cbf8eb99707cf5f50a59f7af88d2b8723b82129fc310cbd0 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-29/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-29/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@sha256:0cd99ca24d8e8c98e67c542213511d985b8778b5bdcbb160e038429496686047" "/opt/rustwide/cargo-home/bin/cargo" "+1.59.0" "test" "--frozen", kill_on_drop: false }` [INFO] [stdout] 127b0297e85629d0da281dbc9b89dc04b7c602d325d4783005a41e9ed1e915a1 [INFO] running `Command { std: "docker" "start" "-a" "127b0297e85629d0da281dbc9b89dc04b7c602d325d4783005a41e9ed1e915a1", kill_on_drop: false }` [INFO] [stderr] warning: unknown `doc` attribute `hide` [INFO] [stderr] --> src/json_builder.rs:510:7 [INFO] [stderr] | [INFO] [stderr] 510 | #[doc(hide)] [INFO] [stderr] | ^^^^ [INFO] [stderr] | [INFO] [stderr] = note: `#[warn(invalid_doc_attributes)]` on by default [INFO] [stderr] = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release! [INFO] [stderr] = note: for more information, see issue #82730 [INFO] [stderr] [INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stderr] --> src/json_builder.rs:365:27 [INFO] [stderr] | [INFO] [stderr] 365 | impl<'a> IntoJSON for &'a IntoJSON { [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 [INFO] [stderr] help: use `dyn` [INFO] [stderr] | [INFO] [stderr] 365 - impl<'a> IntoJSON for &'a IntoJSON { [INFO] [stderr] 365 + impl<'a> IntoJSON for &'a dyn IntoJSON { [INFO] [stderr] | [INFO] [stderr] [INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stderr] --> src/json_builder.rs:26:18 [INFO] [stderr] | [INFO] [stderr] 26 | writer: &'a mut Write, [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 [INFO] [stderr] help: use `dyn` [INFO] [stderr] | [INFO] [stderr] 26 - writer: &'a mut Write, [INFO] [stderr] 26 + writer: &'a mut dyn Write, [INFO] [stderr] | [INFO] [stderr] [INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stderr] --> src/json_builder.rs:66:42 [INFO] [stderr] | [INFO] [stderr] 66 | pub fn escape_json(s: &str, writer: &mut Write) -> std::io::Result<()> { [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 [INFO] [stderr] help: use `dyn` [INFO] [stderr] | [INFO] [stderr] 66 - pub fn escape_json(s: &str, writer: &mut Write) -> std::io::Result<()> { [INFO] [stderr] 66 + pub fn escape_json(s: &str, writer: &mut dyn Write) -> std::io::Result<()> { [INFO] [stderr] | [INFO] [stderr] [INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stderr] --> src/json_builder.rs:135:26 [INFO] [stderr] | [INFO] [stderr] 135 | pub fn new(writer: &mut Write) -> JSONBuilder { [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 [INFO] [stderr] help: use `dyn` [INFO] [stderr] | [INFO] [stderr] 135 - pub fn new(writer: &mut Write) -> JSONBuilder { [INFO] [stderr] 135 + pub fn new(writer: &mut dyn Write) -> JSONBuilder { [INFO] [stderr] | [INFO] [stderr] [INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stderr] --> src/json_builder.rs:144:33 [INFO] [stderr] | [INFO] [stderr] 144 | pub fn new_pretty(writer: &mut Write, indent_size: usize, tab_indent: bool) -> JSONBuilder { [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 [INFO] [stderr] help: use `dyn` [INFO] [stderr] | [INFO] [stderr] 144 - pub fn new_pretty(writer: &mut Write, indent_size: usize, tab_indent: bool) -> JSONBuilder { [INFO] [stderr] 144 + pub fn new_pretty(writer: &mut dyn Write, indent_size: usize, tab_indent: bool) -> JSONBuilder { [INFO] [stderr] | [INFO] [stderr] [INFO] [stderr] warning: `json_builder` (bin "json_builder" test) generated 6 warnings [INFO] [stderr] Finished test [unoptimized + debuginfo] target(s) in 0.00s [INFO] [stderr] Running unittests (/opt/rustwide/target/debug/deps/json_builder-dd5c668a40d93a1f) [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" "127b0297e85629d0da281dbc9b89dc04b7c602d325d4783005a41e9ed1e915a1", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "127b0297e85629d0da281dbc9b89dc04b7c602d325d4783005a41e9ed1e915a1", kill_on_drop: false }` [INFO] [stdout] 127b0297e85629d0da281dbc9b89dc04b7c602d325d4783005a41e9ed1e915a1