It would be easier to diagnose bug 1409276 if we could see what compile commands Rust build scripts were running. It turns out that running `cargo build -vv` will in fact print the build script output during the build, and the cc crate prints a line for each compile it runs, so that ought to be sufficient: https://doc.rust-lang.org/beta/cargo/reference/build-scripts.html#outputs-of-the-build-script

That does the trick: [task 2018-07-03T19:47:15.791Z] 19:47:15 INFO - Running `/builds/worker/workspace/build/src/obj-firefox/testing/geckodriver/./release/build/bzip2-sys-8bf6e02f8bc93b0c/build-script-build` [task 2018-07-03T19:47:15.791Z] 19:47:15 INFO - TARGET = Some("x86_64-unknown-linux-gnu") [task 2018-07-03T19:47:15.791Z] 19:47:15 INFO - OPT_LEVEL = Some("2") [task 2018-07-03T19:47:15.792Z] 19:47:15 INFO - TARGET = Some("x86_64-unknown-linux-gnu") [task 2018-07-03T19:47:15.792Z] 19:47:15 INFO - HOST = Some("x86_64-unknown-linux-gnu") [task 2018-07-03T19:47:15.792Z] 19:47:15 INFO - TARGET = Some("x86_64-unknown-linux-gnu") [task 2018-07-03T19:47:15.792Z] 19:47:15 INFO - TARGET = Some("x86_64-unknown-linux-gnu") [task 2018-07-03T19:47:15.792Z] 19:47:15 INFO - HOST = Some("x86_64-unknown-linux-gnu") [task 2018-07-03T19:47:15.792Z] 19:47:15 INFO - CC_x86_64-unknown-linux-gnu = None [task 2018-07-03T19:47:15.792Z] 19:47:15 INFO - CC_x86_64_unknown_linux_gnu = None [task 2018-07-03T19:47:15.793Z] 19:47:15 INFO - HOST_CC = None [task 2018-07-03T19:47:15.793Z] 19:47:15 INFO - CC = None [task 2018-07-03T19:47:15.793Z] 19:47:15 INFO - HOST = Some("x86_64-unknown-linux-gnu") [task 2018-07-03T19:47:15.793Z] 19:47:15 INFO - TARGET = Some("x86_64-unknown-linux-gnu") [task 2018-07-03T19:47:15.793Z] 19:47:15 INFO - HOST = Some("x86_64-unknown-linux-gnu") [task 2018-07-03T19:47:15.793Z] 19:47:15 INFO - CFLAGS_x86_64-unknown-linux-gnu = None [task 2018-07-03T19:47:15.793Z] 19:47:15 INFO - CFLAGS_x86_64_unknown_linux_gnu = None [task 2018-07-03T19:47:15.793Z] 19:47:15 INFO - HOST_CFLAGS = None [task 2018-07-03T19:47:15.794Z] 19:47:15 INFO - CFLAGS = None [task 2018-07-03T19:47:15.794Z] 19:47:15 INFO - DEBUG = Some("false") [task 2018-07-03T19:47:15.794Z] 19:47:15 INFO - running: "cc" "-O2" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-I" "bzip2-1.0.6" "-DBZ_NO_STDIO" "-o" "/builds/worker/workspace/build/src/obj-firefox/testing/geckodriver/./x86_64-unknown-linux-gnu/release/build/bzip2-sys-32cb3989ac669bdd/out/bzip2-1.0.6/blocksort.o" "-c" "bzip2-1.0.6/blocksort.c" Unfortunately it means we also get a ton of less useful log spew like: [task 2018-07-03T19:53:34.548Z] 19:53:34 INFO - cargo:rerun-if-changed=properties/shorthands/position.mako.rs

Comment on attachment 8989958 [details] bug 1473121 - Pass -vv to cargo build instead of just --verbose when verbose output is requested. https://reviewboard.mozilla.org/r/254958/#review261938

Pushed by gszorc@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/8d7d5087a505 Pass -vv to cargo build instead of just --verbose when verbose output is requested. r=gps