[INFO] cloning repository https://github.com/elycruz/rust-book
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/elycruz/rust-book" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Felycruz%2Frust-book", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Felycruz%2Frust-book'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 437000fc30c4b3e08e8c37934a38856fc5960efd
[INFO] checking elycruz/rust-book against master#385fa9d845dd326c6bbfd58c22244215e431948a for absurd-question-mark-desugar
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Felycruz%2Frust-book" "/workspace/builds/worker-3-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/elycruz/rust-book on toolchain 385fa9d845dd326c6bbfd58c22244215e431948a
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+385fa9d845dd326c6bbfd58c22244215e431948a" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/elycruz/rust-book
[INFO] finished tweaking git repo https://github.com/elycruz/rust-book
[INFO] tweaked toml for git repo https://github.com/elycruz/rust-book written to /workspace/builds/worker-3-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/elycruz/rust-book 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" "+385fa9d845dd326c6bbfd58c22244215e431948a" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded wasi v0.5.0
[INFO] [stderr]   Downloaded getrandom v0.1.11
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-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" "+385fa9d845dd326c6bbfd58c22244215e431948a" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 5b845aba34f89a5de31deee0becde7194e6f51fba52793085326f4d38f8404eb
[INFO] running `Command { std: "docker" "start" "-a" "5b845aba34f89a5de31deee0becde7194e6f51fba52793085326f4d38f8404eb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "5b845aba34f89a5de31deee0becde7194e6f51fba52793085326f4d38f8404eb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5b845aba34f89a5de31deee0becde7194e6f51fba52793085326f4d38f8404eb", kill_on_drop: false }`
[INFO] [stdout] 5b845aba34f89a5de31deee0becde7194e6f51fba52793085326f4d38f8404eb
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-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" "+385fa9d845dd326c6bbfd58c22244215e431948a" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] c9869fdfea952c2e3e88222cde2925f9d9053842850e1a1247e6cc904d5b1b97
[INFO] running `Command { std: "docker" "start" "-a" "c9869fdfea952c2e3e88222cde2925f9d9053842850e1a1247e6cc904d5b1b97", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.62
[INFO] [stderr]    Compiling getrandom v0.1.11
[INFO] [stderr]    Compiling memchr v2.2.1
[INFO] [stderr]     Checking cfg-if v0.1.9
[INFO] [stderr]     Checking ppv-lite86 v0.2.5
[INFO] [stderr]    Compiling bitflags v1.1.0
[INFO] [stderr]     Checking unicode-width v0.1.6
[INFO] [stderr]     Checking thread_local v0.3.6
[INFO] [stderr]     Checking regex-syntax v0.6.11
[INFO] [stderr]     Checking textwrap v0.11.0
[INFO] [stderr]     Checking vec_map v0.8.1
[INFO] [stderr]     Checking c2-chacha v0.2.2
[INFO] [stderr]     Checking aho-corasick v0.7.6
[INFO] [stderr]     Checking atty v0.2.13
[INFO] [stderr]     Checking clap v2.33.0
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking rand_chacha v0.2.1
[INFO] [stderr]     Checking rand v0.7.0
[INFO] [stderr]     Checking regex v1.2.1
[INFO] [stderr]     Checking rust-book v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `std::thread::JoinHandle`
[INFO] [stdout]  --> chp16/chp16_1.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use std::thread::JoinHandle;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `String` is imported redundantly
[INFO] [stdout]  --> chp8/main.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::string::String;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]  --> /rustc/385fa9d845dd326c6bbfd58c22244215e431948a/library/std/src/prelude/mod.rs:134:13
[INFO] [stdout]   |
[INFO] [stdout]   = note: the item `String` is already defined here
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `mean` is never used
[INFO] [stdout]  --> chp8/mean_and_mode.rs:3:4
[INFO] [stdout]   |
[INFO] [stdout] 3 | fn mean(v: &Vec<f64>) -> f64 {
[INFO] [stdout]   |    ^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `mode` is never used
[INFO] [stdout]   --> chp8/mean_and_mode.rs:11:4
[INFO] [stdout]    |
[INFO] [stdout] 11 | fn mode(vs: &Vec<f64>) -> f64 {
[INFO] [stdout]    |    ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: panic message is not a string literal
[INFO] [stdout]   --> chp8/mean_and_mode.rs:45:26
[INFO] [stdout]    |
[INFO] [stdout] 45 |         Err(e) => panic!(e)
[INFO] [stdout]    |                          ^
[INFO] [stdout]    |
[INFO] [stdout]    = note: this usage of `panic!()` is deprecated; it will be a hard error in Rust 2021
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/panic-macro-consistency.html>
[INFO] [stdout]    = note: `#[warn(non_fmt_panics)]` on by default
[INFO] [stdout] help: add a "{}" format string to `Display` the message
[INFO] [stdout]    |
[INFO] [stdout] 45 |         Err(e) => panic!("{}", e)
[INFO] [stdout]    |                          +++++
[INFO] [stdout] help: or use std::panic::panic_any instead
[INFO] [stdout]    |
[INFO] [stdout] 45 |         Err(e) => std::panic::panic_any(e)
[INFO] [stdout]    |                   ~~~~~~~~~~~~~~~~~~~~~
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `String` is imported redundantly
[INFO] [stdout]  --> chp2/guessing_game.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use std::string::String;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]  --> /rustc/385fa9d845dd326c6bbfd58c22244215e431948a/library/std/src/prelude/mod.rs:134:13
[INFO] [stdout]   |
[INFO] [stdout]   = note: the item `String` is already defined here
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `rand` is imported redundantly
[INFO] [stdout]  --> chp2/guessing_game.rs:4:5
[INFO] [stdout]   |
[INFO] [stdout] 4 | use rand;
[INFO] [stdout]   |     ^^^^ the item `rand` is already defined by prelude
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `String` is imported redundantly
[INFO] [stdout]  --> chp8/main.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::string::String;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]  --> /rustc/385fa9d845dd326c6bbfd58c22244215e431948a/library/std/src/prelude/mod.rs:134:13
[INFO] [stdout]   |
[INFO] [stdout]   = note: the item `String` is already defined here
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `String` is imported redundantly
[INFO] [stdout]  --> chp3/twelve_days_of_christmas.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::string::String;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]  --> /rustc/385fa9d845dd326c6bbfd58c22244215e431948a/library/std/src/prelude/mod.rs:134:13
[INFO] [stdout]   |
[INFO] [stdout]   = note: the item `String` is already defined here
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `maximum` is never used
[INFO] [stdout]   --> chp8/main.rs:45:4
[INFO] [stdout]    |
[INFO] [stdout] 45 | fn maximum<T: Ord + Debug>(xs: &Vec<T>) -> Option<&T> {
[INFO] [stdout]    |    ^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: panic message is not a string literal
[INFO] [stdout]   --> chp8/mean_and_mode.rs:45:26
[INFO] [stdout]    |
[INFO] [stdout] 45 |         Err(e) => panic!(e)
[INFO] [stdout]    |                          ^
[INFO] [stdout]    |
[INFO] [stdout]    = note: this usage of `panic!()` is deprecated; it will be a hard error in Rust 2021
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/panic-macro-consistency.html>
[INFO] [stdout]    = note: `#[warn(non_fmt_panics)]` on by default
[INFO] [stdout] help: add a "{}" format string to `Display` the message
[INFO] [stdout]    |
[INFO] [stdout] 45 |         Err(e) => panic!("{}", e)
[INFO] [stdout]    |                          +++++
[INFO] [stdout] help: or use std::panic::panic_any instead
[INFO] [stdout]    |
[INFO] [stdout] 45 |         Err(e) => std::panic::panic_any(e)
[INFO] [stdout]    |                   ~~~~~~~~~~~~~~~~~~~~~
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::thread::JoinHandle`
[INFO] [stdout]  --> chp16/chp16_1.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use std::thread::JoinHandle;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::collections::HashMap`
[INFO] [stdout]    --> chp8/company_directory.rs:178:9
[INFO] [stdout]     |
[INFO] [stdout] 178 |     use std::collections::HashMap;
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `String` is imported redundantly
[INFO] [stdout]  --> chp2/guessing_game.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use std::string::String;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]  --> /rustc/385fa9d845dd326c6bbfd58c22244215e431948a/library/std/src/prelude/mod.rs:134:13
[INFO] [stdout]   |
[INFO] [stdout]   = note: the item `String` is already defined here
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `rand` is imported redundantly
[INFO] [stdout]  --> chp2/guessing_game.rs:4:5
[INFO] [stdout]   |
[INFO] [stdout] 4 | use rand;
[INFO] [stdout]   |     ^^^^ the item `rand` is already defined by prelude
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `String` is imported redundantly
[INFO] [stdout]  --> chp3/twelve_days_of_christmas.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::string::String;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]  --> /rustc/385fa9d845dd326c6bbfd58c22244215e431948a/library/std/src/prelude/mod.rs:134:13
[INFO] [stdout]   |
[INFO] [stdout]   = note: the item `String` is already defined here
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: static `FIVE_O` is never used
[INFO] [stdout]  --> chp3/fib_lib.rs:5:8
[INFO] [stdout]   |
[INFO] [stdout] 5 | static FIVE_O: f64 = 5.0;
[INFO] [stdout]   |        ^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: static `O_FIVE` is never used
[INFO] [stdout]  --> chp3/fib_lib.rs:7:8
[INFO] [stdout]   |
[INFO] [stdout] 7 | static O_FIVE: f64 = 0.5;
[INFO] [stdout]   |        ^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `get_phi` is never used
[INFO] [stdout]   --> chp3/fib_lib.rs:12:4
[INFO] [stdout]    |
[INFO] [stdout] 12 | fn get_phi() -> f64 {
[INFO] [stdout]    |    ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `nth_fib` is never used
[INFO] [stdout]   --> chp3/fib_lib.rs:31:8
[INFO] [stdout]    |
[INFO] [stdout] 31 | pub fn nth_fib(nth: i32) -> i64 {
[INFO] [stdout]    |        ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 4 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 8.83s
[INFO] running `Command { std: "docker" "inspect" "c9869fdfea952c2e3e88222cde2925f9d9053842850e1a1247e6cc904d5b1b97", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c9869fdfea952c2e3e88222cde2925f9d9053842850e1a1247e6cc904d5b1b97", kill_on_drop: false }`
[INFO] [stdout] c9869fdfea952c2e3e88222cde2925f9d9053842850e1a1247e6cc904d5b1b97