[INFO] updating cached repository https://github.com/ghotiphud/rust-intro
[INFO] running `"git" "-c" "credential.helper=" "-c" "credential.helper=/big/crater/work/cargo-home/bin/git-credential-null" "-c" "remote.origin.fetch=refs/heads/*:refs/heads/*" "fetch" "origin" "--force" "--prune"`
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] c72640c3eb4a803d29bd3eb29798bcb85e9b4054
[INFO] testing ghotiphud/rust-intro against 1.38.0 for beta-1.39-1
[INFO] running `"git" "clone" "work/cache/git-repos/https%3A%2F%2Fgithub.com%2Fghotiphud%2Frust-intro" "work/builds/worker-3/source"`
[INFO] [stderr] Cloning into 'work/builds/worker-3/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/ghotiphud/rust-intro on toolchain 1.38.0
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking git repo https://github.com/ghotiphud/rust-intro
[INFO] finished tweaking git repo https://github.com/ghotiphud/rust-intro
[INFO] tweaked toml for git repo https://github.com/ghotiphud/rust-intro written to work/builds/worker-3/source/Cargo.toml
[INFO] crate git repo https://github.com/ghotiphud/rust-intro already has a lockfile, it will not be regenerated
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"docker" "create" "-v" "/big/crater/work/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/big/crater/work/builds/worker-3/source:/opt/rustwide/workdir:ro,Z" "-v" "/big/crater/work/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/big/crater/work/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "MAP_USER_ID=1000" "-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" "--network" "none" "rustops/crates-build-env" "/opt/rustwide/cargo-home/bin/cargo" "+1.38.0" "build" "--frozen"`
[INFO] [stdout] 3e6e93bfac40469f0eaf48b77a0982b40d909369ef6f59cef15f0bb26410cb1b
[INFO] running `"docker" "start" "-a" "3e6e93bfac40469f0eaf48b77a0982b40d909369ef6f59cef15f0bb26410cb1b"`
[INFO] [stderr]    Compiling rust_intro v0.1.0 (/opt/rustwide/workdir)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stderr]  --> src/types.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(core_intrinsics)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `y`
[INFO] [stderr]  --> src/safety.rs:3:9
[INFO] [stderr]   |
[INFO] [stderr] 3 |     let y = &x[0]; //Borrow(Reference) the first element of x
[INFO] [stderr]   |         ^ help: consider prefixing with an underscore: `_y`
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]  --> src/safety.rs:2:9
[INFO] [stderr]   |
[INFO] [stderr] 2 |     let mut x = vec![10, 20]; //Create vec owned by x
[INFO] [stderr]   |         ----^
[INFO] [stderr]   |         |
[INFO] [stderr]   |         help: remove this `mut`
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_mut)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `y`
[INFO] [stderr]  --> src/main.rs:5:9
[INFO] [stderr]   |
[INFO] [stderr] 5 |     let y = &x[0]; //Borrow(Reference) the first element of x
[INFO] [stderr]   |         ^ help: consider prefixing with an underscore: `_y`
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0554`.
[INFO] [stderr] warning: function is never used: `iterator`
[INFO] [stderr]  --> src/main.rs:9:1
[INFO] [stderr]   |
[INFO] [stderr] 9 | fn iterator() {
[INFO] [stderr]   | ^^^^^^^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(dead_code)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: function is never used: `sum_pos`
[INFO] [stderr]   --> src/main.rs:16:1
[INFO] [stderr]    |
[INFO] [stderr] 16 | fn sum_pos(v: &Vec<i32>) -> i32 {
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: Could not compile `rust_intro`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] warning: unused return value of `std::iter::Iterator::collect` that must be used
[INFO] [stderr]    --> src/concurrent.rs:140:5
[INFO] [stderr]     |
[INFO] [stderr] 140 |     handles.into_iter().map(|h| h.join().unwrap()).collect::<Vec<_>>();
[INFO] [stderr]     |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stderr]     = note: if you really need to exhaust the iterator, consider `.for_each(drop)` instead
[INFO] [stderr] 
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "3e6e93bfac40469f0eaf48b77a0982b40d909369ef6f59cef15f0bb26410cb1b"`
[INFO] running `"docker" "rm" "-f" "3e6e93bfac40469f0eaf48b77a0982b40d909369ef6f59cef15f0bb26410cb1b"`
[INFO] [stdout] 3e6e93bfac40469f0eaf48b77a0982b40d909369ef6f59cef15f0bb26410cb1b