From a try log[1]; [task 2018-08-21T04:26:56.995Z] 04:26:56 INFO - env RUSTC_BOOTSTRAP=1 RUSTFLAGS='-C opt-level=2 -C debuginfo=2 ' RUSTC_WRAPPER='/builds/worker/workspace/build/src/sccache2/sccache' CARGO_TARGET_DIR=. RUSTC=/builds/worker/workspace/build/src/rustc/bin/rustc RUSTDOC=/builds/worker/workspace/build/src/rustc/bin/rustdoc RUSTFMT=/builds/worker/workspace/build/src/rustc/bin/rustfmt CC_x86_64_apple_darwin=" /builds/worker/workspace/build/src/sccache2/sccache /builds/worker/workspace/build/src/clang/bin/clang -target x86_64-apple-darwin11 -B /builds/worker/workspace/build/src/cctools/bin -isysroot /builds/worker/workspace/build/src/MacOSX10.11.sdk -std=gnu99" CXX_x86_64_apple_darwin=" /builds/worker/workspace/build/src/sccache2/sccache /builds/worker/workspace/build/src/clang/bin/clang++ -target x86_64-apple-darwin11 -B /builds/worker/workspace/build/src/cctools/bin -isysroot /builds/worker/workspace/build/src/MacOSX10.11.sdk" CFLAGS_x86_64_apple_darwin="-fvisibility=hidden -fvisibility-inlines-hidden -DDEBUG=1 -I/builds/worker/workspace/build/src/devtools/shared/adb/test -I/builds/worker/workspace/build/src/obj-firefox/devtools/shared/adb/test -I/builds/worker/workspace/build/src/obj-firefox/dist/include -I/builds/worker/workspace/build/src/obj-firefox/dist/include/nspr -I/builds/worker/workspace/build/src/obj-firefox/dist/include/nss -fPIC -include /builds/worker/workspace/build/src/obj-firefox/mozilla-config.h -DMOZILLA_CLIENT -Qunused-arguments -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -Qunused-arguments -Wall -Wempty-body -Wignored-qualifiers -Wpointer-arith -Wsign-compare -Wtype-limits -Wunreachable-code -Wunreachable-code-return -Wclass-varargs -Wloop-analysis -Werror=non-literal-null-conversion -Wstring-conversion -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wformat -Wformat-security -Wno-gnu-zero-variadic-macro-arguments -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fno-strict-aliasing -ffunction-sections -fdata-sections -fno-math-errno -pthread -pipe -g -Xclang -load -Xclang /builds/worker/workspace/build/src/obj-firefox/build/clang-plugin/libclang-plugin.so -Xclang -add-plugin -Xclang moz-check -O3 -fno-omit-frame-pointer -Werror" CXXFLAGS_x86_64_apple_darwin="-fvisibility=hidden -fvisibility-inlines-hidden -DDEBUG=1 -I/builds/worker/workspace/build/src/devtools/shared/adb/test -I/builds/worker/workspace/build/src/obj-firefox/devtools/shared/adb/test -I/builds/worker/workspace/build/src/obj-firefox/dist/include -I/builds/worker/workspace/build/src/obj-firefox/dist/include/nspr -I/builds/worker/workspace/build/src/obj-firefox/dist/include/nss -fPIC -DMOZILLA_CLIENT -include /builds/worker/workspace/build/src/obj-firefox/mozilla-config.h -Qunused-arguments -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -Qunused-arguments -Wall -Wempty-body -Wignored-qualifiers -Woverloaded-virtual -Wpointer-arith -Wsign-compare -Wtype-limits -Wunreachable-code -Wunreachable-code-return -Wwrite-strings -Wno-invalid-offsetof -Wclass-varargs -Wloop-analysis -Wc++1z-compat -Wcomma -Wimplicit-fallthrough -Werror=non-literal-null-conversion -Wstring-conversion -Wno-inline-new-delete -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wformat -Wformat-security -Wno-gnu-zero-variadic-macro-arguments -Wno-unknown-warning-option -Wno-return-type-c-linkage -fno-sized-deallocation -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fno-exceptions -fno-strict-aliasing -stdlib=libc++ -fno-rtti -ffunction-sections -fdata-sections -fno-exceptions -fno-math-errno -pthread -pipe -g -Xclang -load -Xclang /builds/worker/workspace/build/src/obj-firefox/build/clang-plugin/libclang-plugin.so -Xclang -add-plugin -Xclang moz-check -O3 -fno-omit-frame-pointer -Werror" AR_x86_64_apple_darwin="/builds/worker/workspace/build/src/cctools/bin/x86_64-apple-darwin11-ar" MOZ_SRC=/builds/worker/workspace/build/src MOZ_DIST=/builds/worker/workspace/build/src/obj-firefox/dist LIBCLANG_PATH="/builds/worker/workspace/build/src/clang/lib" CLANG_PATH="/builds/worker/workspace/build/src/clang/bin/clang" PKG_CONFIG_ALLOW_CROSS=1 RUST_BACKTRACE=full MOZ_TOPOBJDIR=/builds/worker/workspace/build/src/obj-firefox CARGO_INCREMENTAL=0 MOZ_CARGO_WRAP_LDFLAGS="-Wl,-syslibroot,/builds/worker/workspace/build/src/MacOSX10.11.sdk -Wl,-dead_strip -Wl,-executable_path,/builds/worker/workspace/build/src/obj-firefox/dist/bin -Wl,-dead_strip" MOZ_CARGO_WRAP_LD=" /builds/worker/workspace/build/src/sccache2/sccache /builds/worker/workspace/build/src/clang/bin/clang -target x86_64-apple-darwin11 -B /builds/worker/workspace/build/src/cctools/bin -isysroot /builds/worker/workspace/build/src/MacOSX10.11.sdk -std=gnu99" CARGO_TARGET_X86_64_APPLE_DARWIN_LINKER=/builds/worker/workspace/build/src/build/cargo-linker /builds/worker/workspace/build/src/rustc/bin/cargo rustc --frozen --manifest-path /builds/worker/workspace/build/src/devtools/shared/adb/test/Cargo.toml -vv --bin adb --target=x86_64-apple-darwin [task 2018-08-21T04:26:56.995Z] 04:26:56 INFO - Compiling adb v1.0.0 (file:///builds/worker/workspace/build/src/devtools/shared/adb/test) [task 2018-08-21T04:26:56.996Z] 04:26:56 INFO - Running `/builds/worker/workspace/build/src/sccache2/sccache /builds/worker/workspace/build/src/rustc/bin/rustc --crate-name adb devtools/shared/adb/test/adb.rs --crate-type bin --emit=dep-info,link -C opt-level=1 -C panic=abort -C debuginfo=2 -C debug-assertions=on -C metadata=771b9fbad85f2cf4 -C extra-filename=-771b9fbad85f2cf4 --out-dir /builds/worker/workspace/build/src/obj-firefox/devtools/shared/adb/test/./x86_64-apple-darwin/debug/deps --target x86_64-apple-darwin -C linker=/builds/worker/workspace/build/src/build/cargo-linker -L dependency=/builds/worker/workspace/build/src/obj-firefox/devtools/shared/adb/test/./x86_64-apple-darwin/debug/deps -L dependency=/builds/worker/workspace/build/src/obj-firefox/devtools/shared/adb/test/./debug/deps -C opt-level=2 -C debuginfo=2` [task 2018-08-21T04:26:56.996Z] 04:26:56 INFO - error: failed to run dsymutil: No such file or directory (os error 2) [task 2018-08-21T04:26:56.996Z] 04:26:56 INFO - error: aborting due to previous error [1] https://treeherder.mozilla.org/logviewer.html#?job_id=195004452&repo=try&lineNumber=27383

There's a patch for this in bug 1417646.