[INFO] cloning repository https://github.com/tommy725/learning-systems-programming-in-rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/tommy725/learning-systems-programming-in-rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ftommy725%2Flearning-systems-programming-in-rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ftommy725%2Flearning-systems-programming-in-rust'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] ac1eab723f744319f9dbc259652b6f2349e0a88f
[INFO] checking tommy725/learning-systems-programming-in-rust against try#4f260f0f20b3133d20cfb50353c0221943af5796+rustflags=-Dunmustuse_in_always_ok for pr-148577
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ftommy725%2Flearning-systems-programming-in-rust" "/workspace/builds/worker-6-tc2/source", kill_on_drop: false }`
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[INFO] [stderr] done.
[INFO] removed /workspace/builds/worker-6-tc2/source/rust-toolchain
[INFO] started tweaking git repo https://github.com/tommy725/learning-systems-programming-in-rust
[INFO] finished tweaking git repo https://github.com/tommy725/learning-systems-programming-in-rust
[INFO] tweaked toml for git repo https://github.com/tommy725/learning-systems-programming-in-rust written to /workspace/builds/worker-6-tc2/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/tommy725/learning-systems-programming-in-rust on toolchain 4f260f0f20b3133d20cfb50353c0221943af5796
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+4f260f0f20b3133d20cfb50353c0221943af5796" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/tommy725/learning-systems-programming-in-rust 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" "+4f260f0f20b3133d20cfb50353c0221943af5796" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+4f260f0f20b3133d20cfb50353c0221943af5796" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 8e8a4a2902eb84d04fb23d8615720160704d4561a6de56c2b81c61d35149a00e
[INFO] running `Command { std: "docker" "start" "-a" "8e8a4a2902eb84d04fb23d8615720160704d4561a6de56c2b81c61d35149a00e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "8e8a4a2902eb84d04fb23d8615720160704d4561a6de56c2b81c61d35149a00e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8e8a4a2902eb84d04fb23d8615720160704d4561a6de56c2b81c61d35149a00e", kill_on_drop: false }`
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[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-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=forbid -Dunmustuse_in_always_ok" "-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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+4f260f0f20b3133d20cfb50353c0221943af5796" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 104015ab36144f617e7e8c5afd76aa632d315c64b58dbdc681c5efa065a95d7e
[INFO] running `Command { std: "docker" "start" "-a" "104015ab36144f617e7e8c5afd76aa632d315c64b58dbdc681c5efa065a95d7e", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.95
[INFO] [stderr]    Compiling syn v1.0.72
[INFO] [stderr]     Checking crc32fast v1.2.1
[INFO] [stderr]    Compiling proc-macro2 v1.0.26
[INFO] [stderr]    Compiling bzip2-sys v0.1.10+1.0.8
[INFO] [stderr]    Compiling httparse v1.4.1
[INFO] [stderr]    Compiling memoffset v0.6.4
[INFO] [stderr]    Compiling crossbeam-utils v0.8.5
[INFO] [stderr]    Compiling crossbeam-epoch v0.9.5
[INFO] [stderr]     Checking lib v0.1.0 (/opt/rustwide/workdir/lib)
[INFO] [stderr]    Compiling serde v1.0.126
[INFO] [stderr]    Compiling sysinfo v0.18.1
[INFO] [stderr]    Compiling quote v1.0.9
[INFO] [stderr]     Checking crossbeam-channel v0.5.1
[INFO] [stderr]     Checking lock_api v0.4.4
[INFO] [stderr]    Compiling tokio v1.6.0
[INFO] [stderr]     Checking crossbeam-deque v0.8.0
[INFO] [stderr]     Checking slab v0.4.3
[INFO] [stderr]     Checking lazycell v1.3.0
[INFO] [stderr]     Checking chapter9 v0.1.0 (/opt/rustwide/workdir/chapter9)
[INFO] [stderr]     Checking chapter6 v0.1.0 (/opt/rustwide/workdir/chapter6)
[INFO] [stderr]     Checking chapter15 v0.1.0 (/opt/rustwide/workdir/chapter15)
[INFO] [stderr]     Checking chapter5 v0.1.0 (/opt/rustwide/workdir/chapter5)
[INFO] [stderr]     Checking chapter12 v0.1.0 (/opt/rustwide/workdir/chapter12)
[INFO] [stderr]     Checking chapter13 v0.1.0 (/opt/rustwide/workdir/chapter13)
[INFO] [stderr]     Checking chapter16 v0.1.0 (/opt/rustwide/workdir/chapter16)
[INFO] [stderr]     Checking appendix v0.1.0 (/opt/rustwide/workdir/appendix)
[INFO] [stderr]     Checking time v0.1.43
[INFO] [stderr]     Checking flate2 v1.0.20
[INFO] [stderr]     Checking getrandom v0.2.2
[INFO] [stderr]     Checking num_cpus v1.13.0
[INFO] [stderr]     Checking nix v0.21.0
[INFO] [stderr]     Checking bzip2 v0.3.3
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[INFO] [stderr]     Checking parking_lot v0.11.1
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[INFO] [stderr]     Checking rand v0.8.3
[INFO] [stderr]     Checking iovec v0.1.4
[INFO] [stderr]     Checking net2 v0.2.37
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[INFO] [stderr]     Checking nix v0.20.0
[INFO] [stderr]     Checking memmap2 v0.2.2
[INFO] [stderr]     Checking chapter7 v0.1.0 (/opt/rustwide/workdir/chapter7)
[INFO] [stderr]     Checking mio-extras v2.0.6
[INFO] [stderr]     Checking chapter17 v0.1.0 (/opt/rustwide/workdir/chapter17)
[INFO] [stderr]     Checking chapter14 v0.1.0 (/opt/rustwide/workdir/chapter14)
[INFO] [stderr]     Checking notify v4.0.17
[INFO] [stderr]     Checking chapter8 v0.1.0 (/opt/rustwide/workdir/chapter8)
[INFO] [stderr]     Checking chapter1 v0.1.0 (/opt/rustwide/workdir/chapter1)
[INFO] [stderr]     Checking serde_json v1.0.64
[INFO] [stderr]    Compiling thiserror-impl v1.0.24
[INFO] [stderr]    Compiling tokio-macros v1.2.0
[INFO] [stderr]     Checking chapter11 v0.1.0 (/opt/rustwide/workdir/chapter11)
[INFO] [stdout] warning: unreachable expression
[INFO] [stdout]   --> chapter11/src/11_8/main.rs:32:82
[INFO] [stdout]    |
[INFO] [stdout] 32 |             execve(&dir, &[dir.clone(), arg], &[env]).expect("execution failed.");
[INFO] [stdout]    |             ---------------------------------------------------------------------^ unreachable expression
[INFO] [stdout]    |             |
[INFO] [stdout]    |             any code following this expression is unreachable
[INFO] [stdout]    |
[INFO] [stdout] note: this expression has type `Infallible`, which is uninhabited
[INFO] [stdout]   --> chapter11/src/11_8/main.rs:32:13
[INFO] [stdout]    |
[INFO] [stdout] 32 |             execve(&dir, &[dir.clone(), arg], &[env]).expect("execution failed.");
[INFO] [stdout]    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    = note: `#[warn(unreachable_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unreachable expression
[INFO] [stdout]   --> chapter11/src/11_8/main.rs:32:82
[INFO] [stdout]    |
[INFO] [stdout] 32 |             execve(&dir, &[dir.clone(), arg], &[env]).expect("execution failed.");
[INFO] [stdout]    |             ---------------------------------------------------------------------^ unreachable expression
[INFO] [stdout]    |             |
[INFO] [stdout]    |             any code following this expression is unreachable
[INFO] [stdout]    |
[INFO] [stdout] note: this expression has type `Infallible`, which is uninhabited
[INFO] [stdout]   --> chapter11/src/11_8/main.rs:32:13
[INFO] [stdout]    |
[INFO] [stdout] 32 |             execve(&dir, &[dir.clone(), arg], &[env]).expect("execution failed.");
[INFO] [stdout]    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    = note: `#[warn(unreachable_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Checking chapter2 v0.1.0 (/opt/rustwide/workdir/chapter2)
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]  --> chapter2/src/2_4_3/main.rs:6:13
[INFO] [stdout]   |
[INFO] [stdout] 6 |     IoError(std::io::Error),
[INFO] [stdout]   |     ------- ^^^^^^^^^^^^^^
[INFO] [stdout]   |     |
[INFO] [stdout]   |     field in this variant
[INFO] [stdout]   |
[INFO] [stdout]   = note: `BufferError` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] help: consider changing the field to be of unit type to suppress this warning while preserving the field numbering, or remove the field
[INFO] [stdout]   |
[INFO] [stdout] 6 -     IoError(std::io::Error),
[INFO] [stdout] 6 +     IoError(()),
[INFO] [stdout]   |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]  --> chapter2/src/2_4_3/main.rs:7:14
[INFO] [stdout]   |
[INFO] [stdout] 7 |     StrError(str::Utf8Error),
[INFO] [stdout]   |     -------- ^^^^^^^^^^^^^^
[INFO] [stdout]   |     |
[INFO] [stdout]   |     field in this variant
[INFO] [stdout]   |
[INFO] [stdout]   = note: `BufferError` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] help: consider changing the field to be of unit type to suppress this warning while preserving the field numbering, or remove the field
[INFO] [stdout]   |
[INFO] [stdout] 7 -     StrError(str::Utf8Error),
[INFO] [stdout] 7 +     StrError(()),
[INFO] [stdout]   |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]  --> chapter2/src/2_4_3/main.rs:6:13
[INFO] [stdout]   |
[INFO] [stdout] 6 |     IoError(std::io::Error),
[INFO] [stdout]   |     ------- ^^^^^^^^^^^^^^
[INFO] [stdout]   |     |
[INFO] [stdout]   |     field in this variant
[INFO] [stdout]   |
[INFO] [stdout]   = note: `BufferError` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] help: consider changing the field to be of unit type to suppress this warning while preserving the field numbering, or remove the field
[INFO] [stdout]   |
[INFO] [stdout] 6 -     IoError(std::io::Error),
[INFO] [stdout] 6 +     IoError(()),
[INFO] [stdout]   |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]  --> chapter2/src/2_4_3/main.rs:7:14
[INFO] [stdout]   |
[INFO] [stdout] 7 |     StrError(str::Utf8Error),
[INFO] [stdout]   |     -------- ^^^^^^^^^^^^^^
[INFO] [stdout]   |     |
[INFO] [stdout]   |     field in this variant
[INFO] [stdout]   |
[INFO] [stdout]   = note: `BufferError` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] help: consider changing the field to be of unit type to suppress this warning while preserving the field numbering, or remove the field
[INFO] [stdout]   |
[INFO] [stdout] 7 -     StrError(str::Utf8Error),
[INFO] [stdout] 7 +     StrError(()),
[INFO] [stdout]   |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Checking thiserror v1.0.24
[INFO] [stderr]     Checking zip v0.5.12
[INFO] [stderr]     Checking chapter10 v0.1.0 (/opt/rustwide/workdir/chapter10)
[INFO] [stderr]     Checking chapter3 v0.1.0 (/opt/rustwide/workdir/chapter3)
[INFO] [stdout] warning: fields `name` and `value` are never read
[INFO] [stdout]  --> chapter3/src/3_4_3/main.rs:8:5
[INFO] [stdout]   |
[INFO] [stdout] 7 | struct HeaderOwn {
[INFO] [stdout]   |        --------- fields in this struct
[INFO] [stdout] 8 |     name: String,
[INFO] [stdout]   |     ^^^^
[INFO] [stdout] 9 |     value: String,
[INFO] [stdout]   |     ^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `HeaderOwn` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: this type will no longer be must used: Result<String, Infallible>
[INFO] [stdout]   --> chapter3/src/3_6_2/main.rs:17:35
[INFO] [stdout]    |
[INFO] [stdout] 17 |         ($(iter.next().map(|word| word.parse::<$x>().ok().expect(&format!("couldn't parse {}", word))).unwrap(),)*)
[INFO] [stdout]    |                                   ^^^^^^^^^^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 24 |     let (i, f, g, s) = scan!(SOURCE, char::is_whitespace, i32, f64, f64, String);
[INFO] [stdout]    |                        --------------------------------------------------------- in this macro invocation
[INFO] [stdout]    |
[INFO] [stdout]    = note: requested on the command line with `-D unmustuse-in-always-ok`
[INFO] [stdout]    = note: this error originates in the macro `scan` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `chapter3` (bin "3_6_2") due to 1 previous error
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] running `Command { std: "docker" "inspect" "104015ab36144f617e7e8c5afd76aa632d315c64b58dbdc681c5efa065a95d7e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "104015ab36144f617e7e8c5afd76aa632d315c64b58dbdc681c5efa065a95d7e", kill_on_drop: false }`
[INFO] [stdout] 104015ab36144f617e7e8c5afd76aa632d315c64b58dbdc681c5efa065a95d7e