[INFO] cloning repository https://github.com/kungfucop/learnrust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/kungfucop/learnrust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fkungfucop%2Flearnrust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fkungfucop%2Flearnrust'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 32196911f8c4a6b2bca270b67a25078567b89b2e
[INFO] checking kungfucop/learnrust against master#af4a5a13a15fa0c60e06321077ef452f769b42fd for pr-122960-3
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fkungfucop%2Flearnrust" "/workspace/builds/worker-1-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/kungfucop/learnrust on toolchain af4a5a13a15fa0c60e06321077ef452f769b42fd
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+af4a5a13a15fa0c60e06321077ef452f769b42fd" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/kungfucop/learnrust
[INFO] finished tweaking git repo https://github.com/kungfucop/learnrust
[INFO] tweaked toml for git repo https://github.com/kungfucop/learnrust written to /workspace/builds/worker-1-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/kungfucop/learnrust already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+af4a5a13a15fa0c60e06321077ef452f769b42fd" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded ferris-says v0.1.1
[INFO] [stderr]   Downloaded backtrace v0.3.26
[INFO] [stderr]   Downloaded libc v0.2.55
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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" "+af4a5a13a15fa0c60e06321077ef452f769b42fd" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 2a03049cbee0bb01a0c421d4d727fcacadd130e722377247c3e7a8d0f9ede900
[INFO] running `Command { std: "docker" "start" "-a" "2a03049cbee0bb01a0c421d4d727fcacadd130e722377247c3e7a8d0f9ede900", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "2a03049cbee0bb01a0c421d4d727fcacadd130e722377247c3e7a8d0f9ede900", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2a03049cbee0bb01a0c421d4d727fcacadd130e722377247c3e7a8d0f9ede900", kill_on_drop: false }`
[INFO] [stdout] 2a03049cbee0bb01a0c421d4d727fcacadd130e722377247c3e7a8d0f9ede900
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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=forbid" "-e" "RUSTDOCFLAGS=--cap-lints=forbid" "-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" "+af4a5a13a15fa0c60e06321077ef452f769b42fd" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 583f49f11b26b3fc2cb319c5a5522fa9a7fc2c52e1cb527a92f58d289206a785
[INFO] running `Command { std: "docker" "start" "-a" "583f49f11b26b3fc2cb319c5a5522fa9a7fc2c52e1cb527a92f58d289206a785", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.55
[INFO] [stderr]    Compiling backtrace-sys v0.1.28
[INFO] [stderr]     Checking rustc-demangle v0.1.14
[INFO] [stderr]     Checking bitflags v1.0.4
[INFO] [stderr]     Checking smallvec v0.4.5
[INFO] [stderr]    Compiling backtrace v0.3.26
[INFO] [stderr]     Checking textwrap v0.11.0
[INFO] [stderr]     Checking atty v0.2.11
[INFO] [stderr]     Checking clap v2.33.0
[INFO] [stderr]     Checking error-chain v0.10.0
[INFO] [stderr]     Checking ferris-says v0.1.1
[INFO] [stderr]     Checking Rust v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0583]: file not found for module `LearnErrorHandling`
[INFO] [stdout]  --> src/main.rs:8:1
[INFO] [stdout]   |
[INFO] [stdout] 8 | mod LearnErrorHandling;
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = help: to create the module `LearnErrorHandling`, create file "src/LearnErrorHandling.rs" or "src/LearnErrorHandling/mod.rs"
[INFO] [stdout]   = note: if there is a `mod LearnErrorHandling` elsewhere in the crate already, import it with `use crate::...` instead
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0583]: file not found for module `LearnErrorHandling`
[INFO] [stdout]  --> src/main.rs:8:1
[INFO] [stdout]   |
[INFO] [stdout] 8 | mod LearnErrorHandling;
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = help: to create the module `LearnErrorHandling`, create file "src/LearnErrorHandling.rs" or "src/LearnErrorHandling/mod.rs"
[INFO] [stdout]   = note: if there is a `mod LearnErrorHandling` elsewhere in the crate already, import it with `use crate::...` instead
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `core::fmt::Alignment::Left`
[INFO] [stdout]  --> src/main.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use core::fmt::Alignment::Left;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `core::fmt::Alignment::Left`
[INFO] [stdout]  --> src/main.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use core::fmt::Alignment::Left;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary parentheses around method argument
[INFO] [stdout]   --> src/LearnIterator.rs:45:32
[INFO] [stdout]    |
[INFO] [stdout] 45 |     let result = v.iter().find((|idx| { *idx % 2 == 0 }));
[INFO] [stdout]    |                                ^                       ^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_parens)]` on by default
[INFO] [stdout] help: remove these parentheses
[INFO] [stdout]    |
[INFO] [stdout] 45 -     let result = v.iter().find((|idx| { *idx % 2 == 0 }));
[INFO] [stdout] 45 +     let result = v.iter().find(|idx| { *idx % 2 == 0 });
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary parentheses around method argument
[INFO] [stdout]   --> src/LearnIterator.rs:45:32
[INFO] [stdout]    |
[INFO] [stdout] 45 |     let result = v.iter().find((|idx| { *idx % 2 == 0 }));
[INFO] [stdout]    |                                ^                       ^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_parens)]` on by default
[INFO] [stdout] help: remove these parentheses
[INFO] [stdout]    |
[INFO] [stdout] 45 -     let result = v.iter().find((|idx| { *idx % 2 == 0 }));
[INFO] [stdout] 45 +     let result = v.iter().find(|idx| { *idx % 2 == 0 });
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `Clone` is imported redundantly
[INFO] [stdout]  --> src/LearnTrait.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::clone::Clone;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^
[INFO] [stdout]  --> /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/prelude/mod.rs:134:13
[INFO] [stdout]   |
[INFO] [stdout]   = note: the item `Clone` is already defined here
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `Clone` is imported redundantly
[INFO] [stdout]  --> src/LearnTrait.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::clone::Clone;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^
[INFO] [stdout]  --> /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/prelude/mod.rs:134:13
[INFO] [stdout]   |
[INFO] [stdout]   = note: the item `Clone` is already defined here
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `PartialOrd` is imported redundantly
[INFO] [stdout]  --> src/LearnTrait.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | use std::cmp::PartialOrd;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]  --> /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/prelude/mod.rs:134:13
[INFO] [stdout]   |
[INFO] [stdout]   = note: the item `PartialOrd` is already defined here
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `String` is imported redundantly
[INFO] [stdout]  --> src/LearnTrait.rs:5:5
[INFO] [stdout]   |
[INFO] [stdout] 5 | use std::string::String;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]  --> /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/prelude/mod.rs:134:13
[INFO] [stdout]   |
[INFO] [stdout]   = note: the item `String` is already defined here
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `PartialOrd` is imported redundantly
[INFO] [stdout]  --> src/LearnTrait.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | use std::cmp::PartialOrd;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]  --> /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/prelude/mod.rs:134:13
[INFO] [stdout]   |
[INFO] [stdout]   = note: the item `PartialOrd` is already defined here
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `String` is imported redundantly
[INFO] [stdout]  --> src/LearnTrait.rs:5:5
[INFO] [stdout]   |
[INFO] [stdout] 5 | use std::string::String;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]  --> /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/prelude/mod.rs:134:13
[INFO] [stdout]   |
[INFO] [stdout]   = note: the item `String` is already defined here
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::string::ToString`
[INFO] [stdout]  --> src/LearnTrait.rs:6:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | use std::string::ToString;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::string::ToString`
[INFO] [stdout]  --> src/LearnTrait.rs:6:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | use std::string::ToString;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary parentheses around function argument
[INFO] [stdout]   --> src/LearnTrait.rs:60:27
[INFO] [stdout]    |
[INFO] [stdout] 60 |     traitReferenceSummary((student))
[INFO] [stdout]    |                           ^       ^
[INFO] [stdout]    |
[INFO] [stdout] help: remove these parentheses
[INFO] [stdout]    |
[INFO] [stdout] 60 -     traitReferenceSummary((student))
[INFO] [stdout] 60 +     traitReferenceSummary(student)
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary parentheses around function argument
[INFO] [stdout]   --> src/LearnTrait.rs:60:27
[INFO] [stdout]    |
[INFO] [stdout] 60 |     traitReferenceSummary((student))
[INFO] [stdout]    |                           ^       ^
[INFO] [stdout]    |
[INFO] [stdout] help: remove these parentheses
[INFO] [stdout]    |
[INFO] [stdout] 60 -     traitReferenceSummary((student))
[INFO] [stdout] 60 +     traitReferenceSummary(student)
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/LearnTrait.rs:115:17
[INFO] [stdout]     |
[INFO] [stdout] 115 | fn foo() -> Box<Fn(i32) -> i32> {
[INFO] [stdout]     |                 ^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) 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: if this is an object-safe trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 115 | fn foo() -> Box<dyn Fn(i32) -> i32> {
[INFO] [stdout]     |                 +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/LearnTrait.rs:115:17
[INFO] [stdout]     |
[INFO] [stdout] 115 | fn foo() -> Box<Fn(i32) -> i32> {
[INFO] [stdout]     |                 ^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2018) 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: if this is an object-safe trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 115 | fn foo() -> Box<dyn Fn(i32) -> i32> {
[INFO] [stdout]     |                 +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/Closure.rs:48:37
[INFO] [stdout]    |
[INFO] [stdout] 48 |     fn call_with_one(some_closure: &Fn(i32) -> i32) -> i32 {
[INFO] [stdout]    |                                     ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2018) 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: if this is an object-safe trait, use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 48 |     fn call_with_one(some_closure: &dyn Fn(i32) -> i32) -> i32 {
[INFO] [stdout]    |                                     +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/Closure.rs:62:32
[INFO] [stdout]    |
[INFO] [stdout] 62 |     fn callClousure(clousure: &Fn(i32) -> i32) -> i32 {
[INFO] [stdout]    |                                ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2018) 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: if this is an object-safe trait, use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 62 |     fn callClousure(clousure: &dyn Fn(i32) -> i32) -> i32 {
[INFO] [stdout]    |                                +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/Closure.rs:48:37
[INFO] [stdout]    |
[INFO] [stdout] 48 |     fn call_with_one(some_closure: &Fn(i32) -> i32) -> i32 {
[INFO] [stdout]    |                                     ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2018) 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: if this is an object-safe trait, use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 48 |     fn call_with_one(some_closure: &dyn Fn(i32) -> i32) -> i32 {
[INFO] [stdout]    |                                     +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/Closure.rs:72:25
[INFO] [stdout]    |
[INFO] [stdout] 72 |     fn factory() -> Box<Fn(i32) -> i32> {
[INFO] [stdout]    |                         ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2018) 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: if this is an object-safe trait, use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 72 |     fn factory() -> Box<dyn Fn(i32) -> i32> {
[INFO] [stdout]    |                         +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/Closure.rs:62:32
[INFO] [stdout]    |
[INFO] [stdout] 62 |     fn callClousure(clousure: &Fn(i32) -> i32) -> i32 {
[INFO] [stdout]    |                                ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2018) 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: if this is an object-safe trait, use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 62 |     fn callClousure(clousure: &dyn Fn(i32) -> i32) -> i32 {
[INFO] [stdout]    |                                +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/Closure.rs:72:25
[INFO] [stdout]    |
[INFO] [stdout] 72 |     fn factory() -> Box<Fn(i32) -> i32> {
[INFO] [stdout]    |                         ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2018) 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: if this is an object-safe trait, use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 72 |     fn factory() -> Box<dyn Fn(i32) -> i32> {
[INFO] [stdout]    |                         +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `idx`
[INFO] [stdout]   --> src/LearnIterator.rs:36:16
[INFO] [stdout]    |
[INFO] [stdout] 36 |         .map(|(idx, val)| val)
[INFO] [stdout]    |                ^^^ help: if this is intentional, prefix it with an underscore: `_idx`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `idx`
[INFO] [stdout]   --> src/LearnIterator.rs:36:16
[INFO] [stdout]    |
[INFO] [stdout] 36 |         .map(|(idx, val)| val)
[INFO] [stdout]    |                ^^^ help: if this is intentional, prefix it with an underscore: `_idx`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `list`
[INFO] [stdout]   --> src/LearnBox.rs:15:9
[INFO] [stdout]    |
[INFO] [stdout] 15 |     let list = List::Cons(1, Box::new(List::Cons(2, Box::new(List::Nil))));
[INFO] [stdout]    |         ^^^^ help: if this is intentional, prefix it with an underscore: `_list`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `list`
[INFO] [stdout]   --> src/LearnBox.rs:15:9
[INFO] [stdout]    |
[INFO] [stdout] 15 |     let list = List::Cons(1, Box::new(List::Cons(2, Box::new(List::Nil))));
[INFO] [stdout]    |         ^^^^ help: if this is intentional, prefix it with an underscore: `_list`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `item1`
[INFO] [stdout]   --> src/LearnTrait.rs:73:16
[INFO] [stdout]    |
[INFO] [stdout] 73 | pub fn notify2(item1: impl Summary, item2: impl Summary) {}
[INFO] [stdout]    |                ^^^^^ help: if this is intentional, prefix it with an underscore: `_item1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `item2`
[INFO] [stdout]   --> src/LearnTrait.rs:73:37
[INFO] [stdout]    |
[INFO] [stdout] 73 | pub fn notify2(item1: impl Summary, item2: impl Summary) {}
[INFO] [stdout]    |                                     ^^^^^ help: if this is intentional, prefix it with an underscore: `_item2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `item`
[INFO] [stdout]   --> src/LearnTrait.rs:75:38
[INFO] [stdout]    |
[INFO] [stdout] 75 | pub fn notify3<T: Summary + Display>(item: T) {}
[INFO] [stdout]    |                                      ^^^^ help: if this is intentional, prefix it with an underscore: `_item`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `t`
[INFO] [stdout]   --> src/LearnTrait.rs:77:24
[INFO] [stdout]    |
[INFO] [stdout] 77 | fn some_function<T, U>(t: T, u: U) -> i32
[INFO] [stdout]    |                        ^ help: if this is intentional, prefix it with an underscore: `_t`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `u`
[INFO] [stdout]   --> src/LearnTrait.rs:77:30
[INFO] [stdout]    |
[INFO] [stdout] 77 | fn some_function<T, U>(t: T, u: U) -> i32
[INFO] [stdout]    |                              ^ help: if this is intentional, prefix it with an underscore: `_u`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `lft`
[INFO] [stdout]    --> src/LearnTrait.rs:137:9
[INFO] [stdout]     |
[INFO] [stdout] 137 |     let lft = LifeTimeTrick { name:&name };
[INFO] [stdout]     |         ^^^ help: if this is intentional, prefix it with an underscore: `_lft`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s2`
[INFO] [stdout]   --> src/LearnOwnership.rs:19:9
[INFO] [stdout]    |
[INFO] [stdout] 19 |     let s2 = s1; // now s1 pointer is invalid
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `d3`
[INFO] [stdout]   --> src/LearnOwnership.rs:32:13
[INFO] [stdout]    |
[INFO] [stdout] 32 |         let d3: &mut i32 = &mut d1;
[INFO] [stdout]    |             ^^ help: if this is intentional, prefix it with an underscore: `_d3`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `d3`
[INFO] [stdout]   --> src/LearnOwnership.rs:36:9
[INFO] [stdout]    |
[INFO] [stdout] 36 |     let d3: &mut i32 = &mut d1;
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_d3`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `y2`
[INFO] [stdout]   --> src/LearnOwnership.rs:47:9
[INFO] [stdout]    |
[INFO] [stdout] 47 |     let y2 = &mut x2;
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_y2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `y3`
[INFO] [stdout]   --> src/LearnOwnership.rs:48:9
[INFO] [stdout]    |
[INFO] [stdout] 48 |     let y3 = &mut x2;// this mut is ok
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_y3`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `item1`
[INFO] [stdout]   --> src/LearnTrait.rs:73:16
[INFO] [stdout]    |
[INFO] [stdout] 73 | pub fn notify2(item1: impl Summary, item2: impl Summary) {}
[INFO] [stdout]    |                ^^^^^ help: if this is intentional, prefix it with an underscore: `_item1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `item2`
[INFO] [stdout]   --> src/LearnTrait.rs:73:37
[INFO] [stdout]    |
[INFO] [stdout] 73 | pub fn notify2(item1: impl Summary, item2: impl Summary) {}
[INFO] [stdout]    |                                     ^^^^^ help: if this is intentional, prefix it with an underscore: `_item2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `item`
[INFO] [stdout]   --> src/LearnTrait.rs:75:38
[INFO] [stdout]    |
[INFO] [stdout] 75 | pub fn notify3<T: Summary + Display>(item: T) {}
[INFO] [stdout]    |                                      ^^^^ help: if this is intentional, prefix it with an underscore: `_item`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `t`
[INFO] [stdout]   --> src/LearnTrait.rs:77:24
[INFO] [stdout]    |
[INFO] [stdout] 77 | fn some_function<T, U>(t: T, u: U) -> i32
[INFO] [stdout]    |                        ^ help: if this is intentional, prefix it with an underscore: `_t`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `u`
[INFO] [stdout]   --> src/LearnTrait.rs:77:30
[INFO] [stdout]    |
[INFO] [stdout] 77 | fn some_function<T, U>(t: T, u: U) -> i32
[INFO] [stdout]    |                              ^ help: if this is intentional, prefix it with an underscore: `_u`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/LearnOwnership.rs:107:22
[INFO] [stdout]     |
[INFO] [stdout] 107 | fn implicitLifecycle(x: &str) -> &str {
[INFO] [stdout]     |                      ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `lft`
[INFO] [stdout]    --> src/LearnTrait.rs:137:9
[INFO] [stdout]     |
[INFO] [stdout] 137 |     let lft = LifeTimeTrick { name:&name };
[INFO] [stdout]     |         ^^^ help: if this is intentional, prefix it with an underscore: `_lft`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `plus_num`
[INFO] [stdout]   --> src/Closure.rs:15:9
[INFO] [stdout]    |
[INFO] [stdout] 15 |     let plus_num = |x: i32| x + num;
[INFO] [stdout]    |         ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_plus_num`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `y`
[INFO] [stdout]   --> src/Closure.rs:17:9
[INFO] [stdout]    |
[INFO] [stdout] 17 |     let y = &mut num;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s2`
[INFO] [stdout]   --> src/LearnOwnership.rs:19:9
[INFO] [stdout]    |
[INFO] [stdout] 19 |     let s2 = s1; // now s1 pointer is invalid
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `num` is never read
[INFO] [stdout]   --> src/Closure.rs:24:28
[INFO] [stdout]    |
[INFO] [stdout] 24 |     let mut add = move |x| num = x + 2;
[INFO] [stdout]    |                            ^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout]    = note: `#[warn(unused_assignments)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `num`
[INFO] [stdout]   --> src/Closure.rs:24:28
[INFO] [stdout]    |
[INFO] [stdout] 24 |     let mut add = move |x| num = x + 2;
[INFO] [stdout]    |                            ^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: did you mean to capture by reference instead?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `d3`
[INFO] [stdout]   --> src/LearnOwnership.rs:32:13
[INFO] [stdout]    |
[INFO] [stdout] 32 |         let d3: &mut i32 = &mut d1;
[INFO] [stdout]    |             ^^ help: if this is intentional, prefix it with an underscore: `_d3`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `d3`
[INFO] [stdout]   --> src/LearnOwnership.rs:36:9
[INFO] [stdout]    |
[INFO] [stdout] 36 |     let d3: &mut i32 = &mut d1;
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_d3`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `y2`
[INFO] [stdout]   --> src/LearnOwnership.rs:47:9
[INFO] [stdout]    |
[INFO] [stdout] 47 |     let y2 = &mut x2;
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_y2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `y3`
[INFO] [stdout]   --> src/LearnOwnership.rs:48:9
[INFO] [stdout]    |
[INFO] [stdout] 48 |     let y3 = &mut x2;// this mut is ok
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_y3`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/LearnOwnership.rs:107:22
[INFO] [stdout]     |
[INFO] [stdout] 107 | fn implicitLifecycle(x: &str) -> &str {
[INFO] [stdout]     |                      ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `plus_num`
[INFO] [stdout]   --> src/Closure.rs:15:9
[INFO] [stdout]    |
[INFO] [stdout] 15 |     let plus_num = |x: i32| x + num;
[INFO] [stdout]    |         ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_plus_num`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `y`
[INFO] [stdout]   --> src/Closure.rs:17:9
[INFO] [stdout]    |
[INFO] [stdout] 17 |     let y = &mut num;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `num` is never read
[INFO] [stdout]   --> src/Closure.rs:24:28
[INFO] [stdout]    |
[INFO] [stdout] 24 |     let mut add = move |x| num = x + 2;
[INFO] [stdout]    |                            ^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout]    = note: `#[warn(unused_assignments)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `num`
[INFO] [stdout]   --> src/Closure.rs:24:28
[INFO] [stdout]    |
[INFO] [stdout] 24 |     let mut add = move |x| num = x + 2;
[INFO] [stdout]    |                            ^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: did you mean to capture by reference instead?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `baz`
[INFO] [stdout]   --> src/main.rs:42:9
[INFO] [stdout]    |
[INFO] [stdout] 42 |     let baz = Baz;
[INFO] [stdout]    |         ^^^ help: if this is intentional, prefix it with an underscore: `_baz`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error; 30 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0583`.
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `baz`
[INFO] [stdout]   --> src/main.rs:42:9
[INFO] [stdout]    |
[INFO] [stdout] 42 |     let baz = Baz;
[INFO] [stdout]    |         ^^^ help: if this is intentional, prefix it with an underscore: `_baz`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error; 30 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `Rust` (bin "Rust" test) due to 2 previous errors; 30 warnings emitted
[INFO] [stdout] For more information about this error, try `rustc --explain E0583`.
[INFO] [stdout] 
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: could not compile `Rust` (bin "Rust") due to 2 previous errors; 30 warnings emitted
[INFO] running `Command { std: "docker" "inspect" "583f49f11b26b3fc2cb319c5a5522fa9a7fc2c52e1cb527a92f58d289206a785", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "583f49f11b26b3fc2cb319c5a5522fa9a7fc2c52e1cb527a92f58d289206a785", kill_on_drop: false }`
[INFO] [stdout] 583f49f11b26b3fc2cb319c5a5522fa9a7fc2c52e1cb527a92f58d289206a785