[INFO] cloning repository https://github.com/mingyuan-f/rust_lab
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/mingyuan-f/rust_lab" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmingyuan-f%2Frust_lab", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmingyuan-f%2Frust_lab'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] af85057659389538381af39e3d67127776a3500b
[INFO] checking mingyuan-f/rust_lab against master#ab37a83ae2c829b8597bdcda8244964ebc60b495 for pr-99943
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmingyuan-f%2Frust_lab" "/workspace/builds/worker-4/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/mingyuan-f/rust_lab on toolchain ab37a83ae2c829b8597bdcda8244964ebc60b495
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+ab37a83ae2c829b8597bdcda8244964ebc60b495" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/mingyuan-f/rust_lab
[INFO] finished tweaking git repo https://github.com/mingyuan-f/rust_lab
[INFO] tweaked toml for git repo https://github.com/mingyuan-f/rust_lab written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] crate git repo https://github.com/mingyuan-f/rust_lab already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+ab37a83ae2c829b8597bdcda8244964ebc60b495" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded metatype v0.2.1
[INFO] [stderr]   Downloaded serde_traitobject v0.2.7
[INFO] [stderr]   Downloaded palaver v0.2.8
[INFO] [stderr]   Downloaded build_id v0.2.1
[INFO] [stderr]   Downloaded soa_derive v0.12.0
[INFO] [stderr]   Downloaded relative v0.2.2
[INFO] [stderr]   Downloaded soa_derive_internal v0.12.0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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@sha256:3d1cd00eb6e6ea2a7969240779edeaeff35b24be85036c63b883ba933028a15f" "/opt/rustwide/cargo-home/bin/cargo" "+ab37a83ae2c829b8597bdcda8244964ebc60b495" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 901b948aea729a7deca37fa936f799eeda6e4636fcb1ea819cde2f6ca8aa3af6
[INFO] running `Command { std: "docker" "start" "-a" "901b948aea729a7deca37fa936f799eeda6e4636fcb1ea819cde2f6ca8aa3af6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "901b948aea729a7deca37fa936f799eeda6e4636fcb1ea819cde2f6ca8aa3af6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "901b948aea729a7deca37fa936f799eeda6e4636fcb1ea819cde2f6ca8aa3af6", kill_on_drop: false }`
[INFO] [stdout] 901b948aea729a7deca37fa936f799eeda6e4636fcb1ea819cde2f6ca8aa3af6
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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@sha256:3d1cd00eb6e6ea2a7969240779edeaeff35b24be85036c63b883ba933028a15f" "/opt/rustwide/cargo-home/bin/cargo" "+ab37a83ae2c829b8597bdcda8244964ebc60b495" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] bea800ab0777884ce07c69107aa96ca8f748ba724bfe997d41f0ec5f7053ccc7
[INFO] running `Command { std: "docker" "start" "-a" "bea800ab0777884ce07c69107aa96ca8f748ba724bfe997d41f0ec5f7053ccc7", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.43
[INFO] [stderr]    Compiling unicode-ident v1.0.3
[INFO] [stderr]    Compiling quote v1.0.21
[INFO] [stderr]    Compiling syn v1.0.99
[INFO] [stderr]    Compiling typenum v1.15.0
[INFO] [stderr]    Compiling serde_derive v1.0.144
[INFO] [stderr]    Compiling semver-parser v0.7.0
[INFO] [stderr]    Compiling version_check v0.9.4
[INFO] [stderr]    Compiling libc v0.2.132
[INFO] [stderr]    Compiling serde v1.0.144
[INFO] [stderr]     Checking byteorder v1.4.3
[INFO] [stderr]    Compiling nix v0.15.0
[INFO] [stderr]     Checking stable_deref_trait v1.2.0
[INFO] [stderr]    Compiling heapless v0.5.6
[INFO] [stderr]     Checking bitflags v1.3.2
[INFO] [stderr]     Checking nom v2.2.1
[INFO] [stderr]    Compiling build_id v0.2.1
[INFO] [stderr]     Checking void v1.0.2
[INFO] [stderr]     Checking cfg-if v0.1.10
[INFO] [stderr]     Checking static_assertions v1.1.0
[INFO] [stderr]    Compiling semver v0.9.0
[INFO] [stderr]     Checking hash32 v0.1.1
[INFO] [stderr]     Checking lazy_static v1.4.0
[INFO] [stderr]     Checking cfg-if v1.0.0
[INFO] [stderr]    Compiling relative v0.2.2
[INFO] [stderr]     Checking once_cell v1.14.0
[INFO] [stderr]    Compiling erased-serde v0.3.23
[INFO] [stderr]     Checking twox-hash v1.6.3
[INFO] [stderr]    Compiling rustc_version v0.2.3
[INFO] [stderr]    Compiling serde_json v1.0.85
[INFO] [stderr]     Checking ryu v1.0.11
[INFO] [stderr]     Checking metatype v0.2.1
[INFO] [stderr]     Checking itoa v1.0.3
[INFO] [stderr]    Compiling generic-array v0.14.6
[INFO] [stderr]    Compiling procinfo v0.4.2
[INFO] [stderr]     Checking generic-array v0.13.3
[INFO] [stderr]     Checking generic-array v0.12.4
[INFO] [stderr]     Checking as-slice v0.1.5
[INFO] [stderr]    Compiling soa_derive_internal v0.12.0
[INFO] [stderr]     Checking palaver v0.2.8
[INFO] [stderr]     Checking soa_derive v0.12.0
[INFO] [stderr]     Checking uuid v0.8.2
[INFO] [stderr]     Checking serde_traitobject v0.2.7
[INFO] [stderr]     Checking rust_lab v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]   --> examples/trait.rs:53:9
[INFO] [stdout]    |
[INFO] [stdout] 53 |     let a: Vec<Box<dyn Debug>> = vec![Box::new(D {})];
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `MyStruct3` is never constructed
[INFO] [stdout]   --> examples/vtable.rs:16:8
[INFO] [stdout]    |
[INFO] [stdout] 16 | struct MyStruct3;
[INFO] [stdout]    |        ^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `aa`
[INFO] [stdout]  --> examples/ownership.rs:9:13
[INFO] [stdout]   |
[INFO] [stdout] 9 |         let aa = a.clone();
[INFO] [stdout]   |             ^^ help: if this is intentional, prefix it with an underscore: `_aa`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `a` is never read
[INFO] [stdout]  --> examples/ownership.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | struct A {
[INFO] [stdout]   |        - field in this struct
[INFO] [stdout] 3 |     a: i32,
[INFO] [stdout]   |     ^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `A` has derived impls for the traits `Clone` and `Debug`, but these are intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `value` is never read
[INFO] [stdout]  --> examples/thread.rs:8:5
[INFO] [stdout]   |
[INFO] [stdout] 7 | struct Value {
[INFO] [stdout]   |        ----- field in this struct
[INFO] [stdout] 8 |     value: i32,
[INFO] [stdout]   |     ^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `Value` has derived impls for the traits `Clone` and `Debug`, but these are intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `ref_value` is never read
[INFO] [stdout]   --> examples/thread.rs:16:5
[INFO] [stdout]    |
[INFO] [stdout] 14 | struct S<'v> {
[INFO] [stdout]    |        - field in this struct
[INFO] [stdout] 15 |     value: Value,
[INFO] [stdout] 16 |     ref_value: &'v Value,
[INFO] [stdout]    |     ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]   --> examples/trait_use.rs:20:9
[INFO] [stdout]    |
[INFO] [stdout] 20 |     let a: &dyn TA = &s;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `r1`
[INFO] [stdout]  --> examples/reference_rule.rs:4:9
[INFO] [stdout]   |
[INFO] [stdout] 4 |     let r1 = &s;
[INFO] [stdout]   |         ^^ help: if this is intentional, prefix it with an underscore: `_r1`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `r2`
[INFO] [stdout]  --> examples/reference_rule.rs:5:9
[INFO] [stdout]   |
[INFO] [stdout] 5 |     let r2 = &s; // no problem
[INFO] [stdout]   |         ^^ help: if this is intentional, prefix it with an underscore: `_r2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `r3`
[INFO] [stdout]  --> examples/reference_rule.rs:6:9
[INFO] [stdout]   |
[INFO] [stdout] 6 |     let r3 = &mut s; // BIG PROBLEM
[INFO] [stdout]   |         ^^ help: if this is intentional, prefix it with an underscore: `_r3`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `i`
[INFO] [stdout]   --> examples/reference_rule.rs:12:9
[INFO] [stdout]    |
[INFO] [stdout] 12 |     for i in 0..10 {
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_i`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> examples/reference_rule.rs:10:9
[INFO] [stdout]    |
[INFO] [stdout] 10 |     let mut v = vec![10, 9, 8];
[INFO] [stdout]    |         ----^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 5 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: fields `x` and `y` are never read
[INFO] [stdout]   --> examples/iterator.rs:48:5
[INFO] [stdout]    |
[INFO] [stdout] 47 | struct Vector2 {
[INFO] [stdout]    |        ------- fields in this struct
[INFO] [stdout] 48 |     x: i32,
[INFO] [stdout]    |     ^
[INFO] [stdout] 49 |     y: i32,
[INFO] [stdout]    |     ^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `Vector2` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 13.28s
[INFO] running `Command { std: "docker" "inspect" "bea800ab0777884ce07c69107aa96ca8f748ba724bfe997d41f0ec5f7053ccc7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "bea800ab0777884ce07c69107aa96ca8f748ba724bfe997d41f0ec5f7053ccc7", kill_on_drop: false }`
[INFO] [stdout] bea800ab0777884ce07c69107aa96ca8f748ba724bfe997d41f0ec5f7053ccc7