Since March 13th, the build with an unusual CC/CXX is failing with: env RUSTFLAGS='-C opt-level=1 -C debuginfo=2 ' CARGO_TARGET_DIR=/data/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/toolkit/library RUSTC=/var/lib/jenkins/.cargo/bin/rustc MOZ_SRC=/data/jenkins/workspace/firefox-scan-build MOZ_DIST=/data/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist LIBCLANG_PATH="/usr/lib/llvm-6.0/lib" CLANG_PATH="/usr/lib/llvm-6.0/bin/clang" PKG_CONFIG_ALLOW_CROSS=1 RUST_BACKTRACE=full MOZ_TOPOBJDIR=/data/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu MOZ_CARGO_WRAP_LDFLAGS="-lpthread -Wl,-z,noexecstack -Wl,-z,text -Wl,-z,relro -Wl,--build-id -B /data/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/build/unix/gold -Wl,-rpath-link,/data/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/bin -Wl,-rpath-link,/usr/local/lib -fdiagnostics-color" MOZ_CARGO_WRAP_LD=" /usr/share/clang/scan-build-7/libexec/ccc-analyzer -std=gnu99" CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER=/data/jenkins/workspace/firefox-scan-build/build/cargo-linker /var/lib/jenkins/.cargo/bin/cargo rustc --frozen --manifest-path /data/jenkins/workspace/firefox-scan-build/toolkit/library/rust/Cargo.toml --color=always --lib --target=x86_64-unknown-linux-gnu --features "servo bindgen gecko_debug quantum_render cubeb_pulse_rust cubeb-remoting no-static-ideograph-encoder-tables" -- Compiling libloading v0.5.0 Compiling cubeb-sys v0.4.1 Compiling url v1.6.0 Compiling gleam v0.4.20 Compiling selectors v0.19.0 (file:///data/jenkins/workspace/firefox-scan-build/servo/components/selectors) Compiling cssparser-macros v0.3.0 [...] Compiling cstr-macros v0.1.2 error: failed to run custom build command for `libloading v0.5.0` process didn't exit successfully: `/data/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/toolkit/library/debug/build/libloading-3174efe20a262dee/build-script-build` (exit code: 101) --- stdout cargo:rustc-link-lib=dl TARGET = Some("x86_64-unknown-linux-gnu") OPT_LEVEL = Some("1") TARGET = Some("x86_64-unknown-linux-gnu") HOST = Some("x86_64-unknown-linux-gnu") TARGET = Some("x86_64-unknown-linux-gnu") TARGET = Some("x86_64-unknown-linux-gnu") HOST = Some("x86_64-unknown-linux-gnu") CC_x86_64-unknown-linux-gnu = None CC_x86_64_unknown_linux_gnu = None HOST_CC = None CC = Some(" /usr/share/clang/scan-build-7/libexec/ccc-analyzer -std=gnu99") TARGET = Some("x86_64-unknown-linux-gnu") HOST = Some("x86_64-unknown-linux-gnu") CFLAGS_x86_64-unknown-linux-gnu = None CFLAGS_x86_64_unknown_linux_gnu = None HOST_CFLAGS = None CFLAGS = None DEBUG = Some("true") running: " /usr/share/clang/scan-build-7/libexec/ccc-analyzer -std=gnu99" "-O1" "-ffunction-sections" "-fdata-sections" "-fPIC" "-g" "-m64" "-Wall" "-Wextra" "-o" "/data/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/toolkit/library/debug/build/libloading-485c286172c9e8bd/out/src/os/unix/global_static.o" "-c" "src/os/unix/global_static.c" --- stderr thread 'main' panicked at ' Internal error occurred: Failed to find tool. Is `ccc-analyzer -std=gnu99` installed? ', third_party/rust/cc/src/lib.rs:1984:5 stack backtrace: 0: 0x5606ea94f08b - std::sys::unix::backtrace::tracing::imp::unwind_backtrace::hb18bafd8df1a59a5 at /checkout/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49 1: 0x5606ea95598e - std::sys_common::backtrace::print::he2db06f5f327c580 at /checkout/src/libstd/sys_common/backtrace.rs:68 at /checkout/src/libstd/sys_common/backtrace.rs:57 2: 0x5606ea947340 - std::panicking::default_hook::{{closure}}::hef814c3eb720780d at /checkout/src/libstd/panicking.rs:381 3: 0x5606ea946e7c - std::panicking::default_hook::hf0d3601b84335f7c at /checkout/src/libstd/panicking.rs:397 4: 0x5606ea94772b - std::panicking::rust_panic_with_hook::hf9f34d7f0d667943 at /checkout/src/libstd/panicking.rs:577 5: 0x5606ea94757e - std::panicking::begin_panic::h215af23ff6354aaf at /checkout/src/libstd/panicking.rs:538 6: 0x5606ea9474ea - std::panicking::begin_panic_fmt::h752224a2c436be23 at /checkout/src/libstd/panicking.rs:522 7: 0x5606ea9320a8 - cc::fail::h867170849d987964 at third_party/rust/cc/src/lib.rs:1984 8: 0x5606ea92a61d - cc::Build::compile::h473be22458aa5d22 at third_party/rust/cc/src/lib.rs:875 9: 0x5606ea922139 - build_script_build::main::h7920b511dd924b32 at third_party/rust/libloading/build.rs:27 10: 0x5606ea9223b5 - std::rt::lang_start::{{closure}}::h9ca8055de38f8055 at /checkout/src/libstd/rt.rs:74 11: 0x5606ea947447 - std::panicking::try::do_call::h7d33aea9be52481f at /checkout/src/libstd/rt.rs:59 at /checkout/src/libstd/panicking.rs:480 12: 0x5606ea96790e - __rust_maybe_catch_panic at /checkout/src/libpanic_unwind/lib.rs:101 13: 0x5606ea94eda9 - std::rt::lang_start_internal::h16c0c37ef62d8e5a at /checkout/src/libstd/panicking.rs:459 at /checkout/src/libstd/panic.rs:365 at /checkout/src/libstd/rt.rs:58 14: 0x5606ea9223a7 - std::rt::lang_start::h90b178e1ae3c85cc at /checkout/src/libstd/rt.rs:74 15: 0x7fab05b6c2b0 - __libc_start_main 16: 0x5606ea9204d9 - _start 17: 0x0 - <unknown> warning: build failed, waiting for other jobs to finish... error: build failed /data/jenkins/workspace/firefox-scan-build/config/rules.mk:969: recipe for target 'force-cargo-library-build' failed I am building with scan-build-7 --show-description -analyzer-config stable-report-filename=true -v ./mach --log-no-times build -v Note that ccc-analyze isn't in the PATH (it is called with an absolute path instead).

The bug report in cc-rs for this is at https://github.com/alexcrichton/cc-rs/issues/300