[INFO] cloning repository https://github.com/bookinstock/rust_example
[INFO] running `"git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/bookinstock/rust_example" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbookinstock%2Frust_example"`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbookinstock%2Frust_example'...
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] c83d144f2d500cd60a59da5019b4bc5ca7d2d36f
[INFO] checking bookinstock/rust_example against master#3dbade652ed8ebac70f903e01f51cd92c4e4302c for pr-69741
[INFO] running `"git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbookinstock%2Frust_example" "/workspace/builds/worker-4/source"`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/bookinstock/rust_example on toolchain 3dbade652ed8ebac70f903e01f51cd92c4e4302c
[INFO] running `"/workspace/cargo-home/bin/cargo" "+3dbade652ed8ebac70f903e01f51cd92c4e4302c" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking git repo https://github.com/bookinstock/rust_example
[INFO] finished tweaking git repo https://github.com/bookinstock/rust_example
[INFO] tweaked toml for git repo https://github.com/bookinstock/rust_example written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] crate git repo https://github.com/bookinstock/rust_example already has a lockfile, it will not be regenerated
[INFO] running `"/workspace/cargo-home/bin/cargo" "+3dbade652ed8ebac70f903e01f51cd92c4e4302c" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"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" "MAP_USER_ID=0" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-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" "+3dbade652ed8ebac70f903e01f51cd92c4e4302c" "check" "--frozen" "--all" "--all-targets"`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] dffc645811b6c5f48354ab94e8cc2cbae1759ac4fc7293f34d236866ff0c3f4c
[INFO] running `"docker" "start" "-a" "dffc645811b6c5f48354ab94e8cc2cbae1759ac4fc7293f34d236866ff0c3f4c"`
[INFO] [stderr]     Checking rust_example v0.1.0 (/opt/rustwide/workdir)
[INFO] [stderr] error[E0601]: `main` function not found in crate `std`
[INFO] [stderr]   --> src/bin/std.rs:64:4
[INFO] [stderr]    |
[INFO] [stderr] 64 | */
[INFO] [stderr]    |    ^ consider adding a `main` function to `src/bin/std.rs`
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0601`.
[INFO] [stderr] error: could not compile `rust_example`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error[E0433]: failed to resolve: use of undeclared type or module `futures`
[INFO] [stderr]   --> src/bin/async.rs:10:5
[INFO] [stderr]    |
[INFO] [stderr] 10 | use futures::executor::block_on;
[INFO] [stderr]    |     ^^^^^^^ use of undeclared type or module `futures`
[INFO] [stderr] 
[INFO] [stderr] error[E0433]: failed to resolve: use of undeclared type or module `futures`
[INFO] [stderr]   --> src/bin/async.rs:10:5
[INFO] [stderr]    |
[INFO] [stderr] 10 | use futures::executor::block_on;
[INFO] [stderr]    |     ^^^^^^^ use of undeclared type or module `futures`
[INFO] [stderr] 
[INFO] [stderr] error[E0425]: cannot find function `block_on` in this scope
[INFO] [stderr]   --> src/bin/async.rs:18:5
[INFO] [stderr]    |
[INFO] [stderr] 18 |     block_on(future); // `future` is run and "hello, world!" is printed
[INFO] [stderr]    |     ^^^^^^^^ not found in this scope
[INFO] [stderr] 
[INFO] [stderr] error[E0425]: cannot find function `block_on` in this scope
[INFO] [stderr]   --> src/bin/async.rs:18:5
[INFO] [stderr]    |
[INFO] [stderr] 18 |     block_on(future); // `future` is run and "hello, world!" is printed
[INFO] [stderr]    |     ^^^^^^^^ not found in this scope
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 2 previous errors
[INFO] [stderr] 
[INFO] [stderr] Some errors have detailed explanations: E0425, E0433.
[INFO] [stderr] For more information about an error, try `rustc --explain E0425`.
[INFO] [stderr] error: aborting due to 2 previous errors
[INFO] [stderr] 
[INFO] [stderr] Some errors have detailed explanations: E0425, E0433.
[INFO] [stderr] For more information about an error, try `rustc --explain E0425`.
[INFO] [stderr] error: could not compile `rust_example`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: could not compile `rust_example`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] warning: unused label
[INFO] [stderr]    --> src/bin/control_flow.rs:119:9
[INFO] [stderr]     |
[INFO] [stderr] 119 |         'inner: loop {
[INFO] [stderr]     |         ^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: `#[warn(unused_labels)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: path statement with no effect
[INFO] [stderr]   --> src/bin/expression.rs:18:5
[INFO] [stderr]    |
[INFO] [stderr] 18 |     x;
[INFO] [stderr]    |     ^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(path_statements)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused arithmetic operation that must be used
[INFO] [stderr]   --> src/bin/expression.rs:19:5
[INFO] [stderr]    |
[INFO] [stderr] 19 |     x + 1;
[INFO] [stderr]    |     ^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused arithmetic operation that must be used
[INFO] [stderr]   --> src/bin/expression.rs:36:9
[INFO] [stderr]    |
[INFO] [stderr] 36 |         2 * x;
[INFO] [stderr]    |         ^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: unreachable statement
[INFO] [stderr]    --> src/bin/control_flow.rs:125:9
[INFO] [stderr]     |
[INFO] [stderr] 122 |             break 'outer;
[INFO] [stderr]     |             ------------ any code following this expression is unreachable
[INFO] [stderr] ...
[INFO] [stderr] 125 |         println!("never reach");
[INFO] [stderr]     |         ^^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
[INFO] [stderr]     |
[INFO] [stderr]     = note: `#[warn(unreachable_code)]` on by default
[INFO] [stderr]     = note: this warning originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stderr] 
[INFO] [stderr] warning: struct is never constructed: `Nil`
[INFO] [stderr]   --> src/bin/custom_type.rs:30:8
[INFO] [stderr]    |
[INFO] [stderr] 30 | struct Nil;
[INFO] [stderr]    |        ^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(dead_code)]` on by default
[INFO] [stderr] 
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "dffc645811b6c5f48354ab94e8cc2cbae1759ac4fc7293f34d236866ff0c3f4c"`
[INFO] running `"docker" "rm" "-f" "dffc645811b6c5f48354ab94e8cc2cbae1759ac4fc7293f34d236866ff0c3f4c"`
[INFO] [stdout] dffc645811b6c5f48354ab94e8cc2cbae1759ac4fc7293f34d236866ff0c3f4c