[INFO] updating cached repository embed-rs/stm32f7-discovery2
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/embed-rs/stm32f7-discovery2
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/embed-rs/stm32f7-discovery2" "work/ex/beta-1.38-1/sources/1.37.0/gh/embed-rs/stm32f7-discovery2"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/embed-rs/stm32f7-discovery2'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/embed-rs/stm32f7-discovery2" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/embed-rs/stm32f7-discovery2"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/embed-rs/stm32f7-discovery2'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 2d3892b8ba283c5abe99d05300f05e60091fe60e
[INFO] sha for GitHub repo embed-rs/stm32f7-discovery2: 2d3892b8ba283c5abe99d05300f05e60091fe60e
[INFO] validating manifest of embed-rs/stm32f7-discovery2 on toolchain 1.37.0
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of embed-rs/stm32f7-discovery2 on toolchain beta-2019-08-13
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing embed-rs/stm32f7-discovery2
[INFO] finished frobbing embed-rs/stm32f7-discovery2
[INFO] frobbed toml for embed-rs/stm32f7-discovery2 written to work/ex/beta-1.38-1/sources/1.37.0/gh/embed-rs/stm32f7-discovery2/Cargo.toml
[INFO] started frobbing embed-rs/stm32f7-discovery2
[INFO] finished frobbing embed-rs/stm32f7-discovery2
[INFO] frobbed toml for embed-rs/stm32f7-discovery2 written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/embed-rs/stm32f7-discovery2/Cargo.toml
[INFO] crate embed-rs/stm32f7-discovery2 already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr] error: failed to run `rustc` to learn about target-specific information
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustc - --crate-name ___ --print=file-names --target stm32f7 --crate-type bin --crate-type rlib --crate-type dylib --crate-type cdylib --crate-type staticlib --crate-type proc-macro` (exit code: 1)
[INFO] [stderr] --- stderr
[INFO] [stderr] error: Error loading target specification: Field target-c-int-width in target specification is required
[INFO] [stderr]   |
[INFO] [stderr]   = help: Use `--print target-list` for a list of built-in targets
[INFO] [stderr] 
[INFO] [stderr] 
[ERROR] this task or one of its parent failed!
[ERROR] command `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"` failed