[INFO] cloning repository https://github.com/40tude/err_for_blog_post
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/40tude/err_for_blog_post" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2F40tude%2Ferr_for_blog_post", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2F40tude%2Ferr_for_blog_post'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] dead48de7516fd941cd2af2dcd2f51c5a0d57540
[INFO] checking 40tude/err_for_blog_post against master#292be5c7c05138d753bbd4b30db7a3f1a5c914f7 for pr-148271
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2F40tude%2Ferr_for_blog_post" "/workspace/builds/worker-2-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-2-tc1/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/40tude/err_for_blog_post
[INFO] finished tweaking git repo https://github.com/40tude/err_for_blog_post
[INFO] tweaked toml for git repo https://github.com/40tude/err_for_blog_post written to /workspace/builds/worker-2-tc1/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/40tude/err_for_blog_post on toolchain 292be5c7c05138d753bbd4b30db7a3f1a5c914f7
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+292be5c7c05138d753bbd4b30db7a3f1a5c914f7" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/40tude/err_for_blog_post 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" "+292be5c7c05138d753bbd4b30db7a3f1a5c914f7" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded serde_derive v1.0.226
[INFO] [stderr]   Downloaded serde v1.0.226
[INFO] [stderr]   Downloaded serde_core v1.0.226
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+292be5c7c05138d753bbd4b30db7a3f1a5c914f7" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 9502660f455cf2c0dd37defcd010c942b46ecacff3c61331db32b0ec98164aec
[INFO] running `Command { std: "docker" "start" "-a" "9502660f455cf2c0dd37defcd010c942b46ecacff3c61331db32b0ec98164aec", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "9502660f455cf2c0dd37defcd010c942b46ecacff3c61331db32b0ec98164aec", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9502660f455cf2c0dd37defcd010c942b46ecacff3c61331db32b0ec98164aec", kill_on_drop: false }`
[INFO] [stdout] 9502660f455cf2c0dd37defcd010c942b46ecacff3c61331db32b0ec98164aec
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+292be5c7c05138d753bbd4b30db7a3f1a5c914f7" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] a91fb9b62eeeb1bf57d67e3b696ed5c5c93e8fb8037a46defedde58e5c89222f
[INFO] running `Command { std: "docker" "start" "-a" "a91fb9b62eeeb1bf57d67e3b696ed5c5c93e8fb8037a46defedde58e5c89222f", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.101
[INFO] [stderr]    Compiling unicode-ident v1.0.19
[INFO] [stderr]    Compiling thiserror v2.0.17
[INFO] [stderr]    Compiling serde_core v1.0.226
[INFO] [stderr]    Compiling serde_json v1.0.145
[INFO] [stderr]    Compiling serde v1.0.226
[INFO] [stderr]    Compiling anyhow v1.0.100
[INFO] [stderr]     Checking itoa v1.0.15
[INFO] [stderr]     Checking ryu v1.0.20
[INFO] [stderr]     Checking memchr v2.7.6
[INFO] [stderr]     Checking step_02 v0.1.0 (/opt/rustwide/workdir/02_production/02_project)
[INFO] [stderr]     Checking experimentation v0.1.0 (/opt/rustwide/workdir/01_experimentation)
[INFO] [stderr]     Checking step_00 v0.1.0 (/opt/rustwide/workdir/02_production/00_project)
[INFO] [stderr]     Checking step_01 v0.1.0 (/opt/rustwide/workdir/02_production/01_project)
[INFO] [stderr]    Compiling quote v1.0.40
[INFO] [stderr]    Compiling syn v2.0.106
[INFO] [stderr]    Compiling thiserror-impl v2.0.17
[INFO] [stderr]    Compiling serde_derive v1.0.226
[INFO] [stderr]     Checking step_04 v0.1.0 (/opt/rustwide/workdir/02_production/04_project)
[INFO] [stderr]     Checking step_05 v0.1.0 (/opt/rustwide/workdir/02_production/05_project)
[INFO] [stderr]     Checking step_03 v0.1.0 (/opt/rustwide/workdir/02_production/03_project)
[INFO] [stderr]     Checking step_06 v0.1.0 (/opt/rustwide/workdir/02_production/06_project)
[INFO] [stderr]     Checking u_are_errors v0.1.0 (/opt/rustwide/workdir/00_u_are_errors)
[INFO] [stdout] error[E0277]: the `?` operator can only be used on `Option`s, not `Result`s, in a function that returns `Option`
[INFO] [stdout]   --> 00_u_are_errors/examples/ex12.rs:11:42
[INFO] [stdout]    |
[INFO] [stdout]  7 | fn bad_example() -> Option<File> {
[INFO] [stdout]    | -------------------------------- this function returns an `Option`
[INFO] [stdout] ...
[INFO] [stdout] 11 |     let file = File::open("username.txt")?;
[INFO] [stdout]    |                                          ^ use `.ok()?` if you want to discard the `Result<Infallible, std::io::Error>` error information
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0277`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `u_are_errors` (example "ex12") due to 1 previous error
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stdout] error[E0308]: mismatched types
[INFO] [stdout]  --> 00_u_are_errors/examples/ex03.rs:5:28
[INFO] [stdout]   |
[INFO] [stdout] 5 |     let f: std::fs::File = std::fs::File::open("foo.txt");
[INFO] [stdout]   |            -------------   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `File`, found `Result<File, Error>`
[INFO] [stdout]   |            |
[INFO] [stdout]   |            expected due to this
[INFO] [stdout]   |
[INFO] [stdout]   = note: expected struct `File`
[INFO] [stdout]                found enum `Result<File, std::io::Error>`
[INFO] [stdout] help: consider using `Result::expect` to unwrap the `Result<File, std::io::Error>` value, panicking if the value is a `Result::Err`
[INFO] [stdout]   |
[INFO] [stdout] 5 |     let f: std::fs::File = std::fs::File::open("foo.txt").expect("REASON");
[INFO] [stdout]   |                                                          +++++++++++++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0308`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `u_are_errors` (example "ex03") due to 1 previous error
[INFO] running `Command { std: "docker" "inspect" "a91fb9b62eeeb1bf57d67e3b696ed5c5c93e8fb8037a46defedde58e5c89222f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a91fb9b62eeeb1bf57d67e3b696ed5c5c93e8fb8037a46defedde58e5c89222f", kill_on_drop: false }`
[INFO] [stdout] a91fb9b62eeeb1bf57d67e3b696ed5c5c93e8fb8037a46defedde58e5c89222f
