[INFO] crate cargo-external-doc 0.2.0 is already in cache
[INFO] checking cargo-external-doc-0.2.0 against try#1a608893c03d7722effeb0058e82770bd36b4b3c for pr-66504-1
[INFO] extracting crate cargo-external-doc 0.2.0 into /workspace/builds/worker-14/source
[INFO] validating manifest of crates.io crate cargo-external-doc 0.2.0 on toolchain 1a608893c03d7722effeb0058e82770bd36b4b3c
[INFO] running `"/workspace/cargo-home/bin/cargo" "+1a608893c03d7722effeb0058e82770bd36b4b3c" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking crates.io crate cargo-external-doc 0.2.0
[INFO] finished tweaking crates.io crate cargo-external-doc 0.2.0
[INFO] tweaked toml for crates.io crate cargo-external-doc 0.2.0 written to /workspace/builds/worker-14/source/Cargo.toml
[INFO] crate crates.io crate cargo-external-doc 0.2.0 already has a lockfile, it will not be regenerated
[INFO] running `"/workspace/cargo-home/bin/cargo" "+1a608893c03d7722effeb0058e82770bd36b4b3c" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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" "+1a608893c03d7722effeb0058e82770bd36b4b3c" "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] 607a258bbdd836acb07cac8de1369fa4c8219b008fe38b180a2a0f03b3d52fb3
[INFO] running `"docker" "start" "-a" "607a258bbdd836acb07cac8de1369fa4c8219b008fe38b180a2a0f03b3d52fb3"`
[INFO] [stderr]     Checking cfg-if v0.1.2
[INFO] [stderr]     Checking libc v0.2.39
[INFO] [stderr]     Checking num-traits v0.2.1
[INFO] [stderr]     Checking pest v0.3.3
[INFO] [stderr]     Checking quick-error v1.2.1
[INFO] [stderr]     Checking log v0.4.1
[INFO] [stderr]     Checking log v0.3.9
[INFO] [stderr]     Checking handlebars v0.22.0
[INFO] [stderr]     Checking rand v0.4.2
[INFO] [stderr]     Checking num-traits v0.1.43
[INFO] [stderr]     Checking serde_json v0.8.6
[INFO] [stderr]     Checking rand v0.3.22
[INFO] [stderr]     Checking tempfile v2.2.0
[INFO] [stderr]     Checking cargo-external-doc v0.2.0 (/opt/rustwide/workdir)
[INFO] [stderr] error[E0277]: cannot add-assign `&std::borrow::Cow<'_, str>` to `std::string::String`
[INFO] [stderr]    --> src/main.rs:131:22
[INFO] [stderr]     |
[INFO] [stderr] 131 |             doc_path += &subdir;
[INFO] [stderr]     |                      ^^ no implementation for `std::string::String += &std::borrow::Cow<'_, str>`
[INFO] [stderr]     |
[INFO] [stderr]     = help: the trait `std::ops::AddAssign<&std::borrow::Cow<'_, str>>` is not implemented for `std::string::String`
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0277`.
[INFO] [stderr] error: could not compile `cargo-external-doc`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error[E0277]: cannot add-assign `&std::borrow::Cow<'_, str>` to `std::string::String`
[INFO] [stderr]    --> src/main.rs:131:22
[INFO] [stderr]     |
[INFO] [stderr] 131 |             doc_path += &subdir;
[INFO] [stderr]     |                      ^^ no implementation for `std::string::String += &std::borrow::Cow<'_, str>`
[INFO] [stderr]     |
[INFO] [stderr]     = help: the trait `std::ops::AddAssign<&std::borrow::Cow<'_, str>>` is not implemented for `std::string::String`
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0277`.
[INFO] [stderr] error: could not compile `cargo-external-doc`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "607a258bbdd836acb07cac8de1369fa4c8219b008fe38b180a2a0f03b3d52fb3"`
[INFO] running `"docker" "rm" "-f" "607a258bbdd836acb07cac8de1369fa4c8219b008fe38b180a2a0f03b3d52fb3"`
[INFO] [stdout] 607a258bbdd836acb07cac8de1369fa4c8219b008fe38b180a2a0f03b3d52fb3