[INFO] cloning repository https://github.com/vedranvinko/oscar
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/vedranvinko/oscar" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fvedranvinko%2Foscar", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fvedranvinko%2Foscar'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 580f1c03d30f09afd9a3056db7eae2b13b492d46
[INFO] testing vedranvinko/oscar against master#8534be72fc3b9c5f2f2dc4e4ee7b651a008e9a3e for pr-74409
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fvedranvinko%2Foscar" "/workspace/builds/worker-9/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-9/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/vedranvinko/oscar on toolchain 8534be72fc3b9c5f2f2dc4e4ee7b651a008e9a3e
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+8534be72fc3b9c5f2f2dc4e4ee7b651a008e9a3e" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/vedranvinko/oscar
[INFO] finished tweaking git repo https://github.com/vedranvinko/oscar
[INFO] tweaked toml for git repo https://github.com/vedranvinko/oscar written to /workspace/builds/worker-9/source/Cargo.toml
[INFO] crate git repo https://github.com/vedranvinko/oscar already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+8534be72fc3b9c5f2f2dc4e4ee7b651a008e9a3e" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--network" "none" "rustops/crates-build-env@sha256:d9fbb4e2287ab3795bdefaf705efb7541a8875c13bce71e067d6b01dc5ed759b" "/opt/rustwide/cargo-home/bin/cargo" "+8534be72fc3b9c5f2f2dc4e4ee7b651a008e9a3e" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 2bfd8ac4c389984a50db8edeeaf8816c70c04f5d4143daf14f5421752b3144e7
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "2bfd8ac4c389984a50db8edeeaf8816c70c04f5d4143daf14f5421752b3144e7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "2bfd8ac4c389984a50db8edeeaf8816c70c04f5d4143daf14f5421752b3144e7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2bfd8ac4c389984a50db8edeeaf8816c70c04f5d4143daf14f5421752b3144e7", kill_on_drop: false }`
[INFO] [stdout] 2bfd8ac4c389984a50db8edeeaf8816c70c04f5d4143daf14f5421752b3144e7
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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@sha256:d9fbb4e2287ab3795bdefaf705efb7541a8875c13bce71e067d6b01dc5ed759b" "/opt/rustwide/cargo-home/bin/cargo" "+8534be72fc3b9c5f2f2dc4e4ee7b651a008e9a3e" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 2bbd0ce2b771d70a2cd1d15aeaa3499d90ff449e838c13568c83bb42da6e0795
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "2bbd0ce2b771d70a2cd1d15aeaa3499d90ff449e838c13568c83bb42da6e0795", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.18
[INFO] [stderr]    Compiling unicode-xid v0.2.0
[INFO] [stderr]    Compiling syn v1.0.31
[INFO] [stderr]    Compiling gimli v0.21.0
[INFO] [stderr]    Compiling log v0.4.8
[INFO] [stderr]    Compiling serde v1.0.112
[INFO] [stderr]    Compiling vec_map v0.8.2
[INFO] [stderr]    Compiling strsim v0.8.0
[INFO] [stderr]    Compiling xml-rs v0.8.3
[INFO] [stderr]    Compiling ansi_term v0.11.0
[INFO] [stderr]    Compiling atty v0.2.14
[INFO] [stderr]    Compiling clap v2.33.1
[INFO] [stderr]    Compiling quote v1.0.7
[INFO] [stderr]    Compiling addr2line v0.12.1
[INFO] [stderr]    Compiling backtrace v0.3.49
[INFO] [stderr]    Compiling error-chain v0.10.0
[INFO] [stderr]    Compiling serde_derive v1.0.112
[INFO] [stderr]    Compiling serde-xml-rs v0.3.1
[INFO] [stderr]    Compiling oscar v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `serde_xml_rs::from_reader`
[INFO] [stdout]  --> src/main.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | use serde_xml_rs::from_reader;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `std::ops::Try`)
[INFO] [stdout]   --> src/main.rs:15:20
[INFO] [stdout]    |
[INFO] [stdout] 14 | / fn read_file(f: String) -> String {
[INFO] [stdout] 15 | |     let mut file = File::open(f)?;
[INFO] [stdout]    | |                    ^^^^^^^^^^^^^^ cannot use the `?` operator in a function that returns `std::string::String`
[INFO] [stdout] 16 | |     let mut content = String::new();
[INFO] [stdout] 17 | |     file.read_to_string(&mut content)?;
[INFO] [stdout] 18 | |
[INFO] [stdout] 19 | |     content
[INFO] [stdout] 20 | | }
[INFO] [stdout]    | |_- this function should return `Result` or `Option` to accept `?`
[INFO] [stdout]    |
[INFO] [stdout]    = help: the trait `std::ops::Try` is not implemented for `std::string::String`
[INFO] [stdout]    = note: required by `std::ops::Try::from_error`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `std::ops::Try`)
[INFO] [stdout]   --> src/main.rs:17:5
[INFO] [stdout]    |
[INFO] [stdout] 14 | / fn read_file(f: String) -> String {
[INFO] [stdout] 15 | |     let mut file = File::open(f)?;
[INFO] [stdout] 16 | |     let mut content = String::new();
[INFO] [stdout] 17 | |     file.read_to_string(&mut content)?;
[INFO] [stdout]    | |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot use the `?` operator in a function that returns `std::string::String`
[INFO] [stdout] 18 | |
[INFO] [stdout] 19 | |     content
[INFO] [stdout] 20 | | }
[INFO] [stdout]    | |_- this function should return `Result` or `Option` to accept `?`
[INFO] [stdout]    |
[INFO] [stdout]    = help: the trait `std::ops::Try` is not implemented for `std::string::String`
[INFO] [stdout]    = note: required by `std::ops::Try::from_error`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 previous errors; 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0277`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `oscar`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "2bbd0ce2b771d70a2cd1d15aeaa3499d90ff449e838c13568c83bb42da6e0795", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2bbd0ce2b771d70a2cd1d15aeaa3499d90ff449e838c13568c83bb42da6e0795", kill_on_drop: false }`
[INFO] [stdout] 2bbd0ce2b771d70a2cd1d15aeaa3499d90ff449e838c13568c83bb42da6e0795