[INFO] fetching crate rustovio 0.1.0... [INFO] testing rustovio-0.1.0 against master#cdb45c87e2cd43495379f7e867e3cc15dcee9f93 for pr-145838-1 [INFO] extracting crate rustovio 0.1.0 into /workspace/builds/worker-0-tc1/source [INFO] started tweaking crates.io crate rustovio 0.1.0 [INFO] finished tweaking crates.io crate rustovio 0.1.0 [INFO] tweaked toml for crates.io crate rustovio 0.1.0 written to /workspace/builds/worker-0-tc1/source/Cargo.toml [INFO] validating manifest of crates.io crate rustovio 0.1.0 on toolchain cdb45c87e2cd43495379f7e867e3cc15dcee9f93 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+cdb45c87e2cd43495379f7e867e3cc15dcee9f93" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] crate crates.io crate rustovio 0.1.0 already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+cdb45c87e2cd43495379f7e867e3cc15dcee9f93" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] [stderr] Downloading crates ... [INFO] [stderr] Downloaded clang-sys v1.2.0 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/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" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:7ad1b28ee6f5f7f699f6cf7015098d6ccdd96d6f2d78dd06228f5b4c9faf309c" "/opt/rustwide/cargo-home/bin/cargo" "+cdb45c87e2cd43495379f7e867e3cc15dcee9f93" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] c33bfd6713a45ec3faf2f7e8f2e5f4a28c939432afe15b13407fb5497b204915 [INFO] running `Command { std: "docker" "start" "-a" "c33bfd6713a45ec3faf2f7e8f2e5f4a28c939432afe15b13407fb5497b204915", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "c33bfd6713a45ec3faf2f7e8f2e5f4a28c939432afe15b13407fb5497b204915", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "c33bfd6713a45ec3faf2f7e8f2e5f4a28c939432afe15b13407fb5497b204915", kill_on_drop: false }` [INFO] [stdout] c33bfd6713a45ec3faf2f7e8f2e5f4a28c939432afe15b13407fb5497b204915 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/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" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "RUSTDOCFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:7ad1b28ee6f5f7f699f6cf7015098d6ccdd96d6f2d78dd06228f5b4c9faf309c" "/opt/rustwide/cargo-home/bin/cargo" "+cdb45c87e2cd43495379f7e867e3cc15dcee9f93" "build" "--frozen" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] 44035ddebc81fd5064724bece9b62d752999368ea10fa6280ec18c8f5190927a [INFO] running `Command { std: "docker" "start" "-a" "44035ddebc81fd5064724bece9b62d752999368ea10fa6280ec18c8f5190927a", kill_on_drop: false }` [INFO] [stderr] Compiling libc v0.2.97 [INFO] [stderr] Compiling memchr v2.4.0 [INFO] [stderr] Compiling glob v0.3.0 [INFO] [stderr] Compiling cfg-if v1.0.0 [INFO] [stderr] Compiling bitflags v1.2.1 [INFO] [stderr] Compiling proc-macro2 v1.0.27 [INFO] [stderr] Compiling unicode-width v0.1.8 [INFO] [stderr] Compiling regex-syntax v0.6.25 [INFO] [stderr] Compiling vec_map v0.8.2 [INFO] [stderr] Compiling termcolor v1.1.2 [INFO] [stderr] Compiling humantime v2.1.0 [INFO] [stderr] Compiling bindgen v0.58.1 [INFO] [stderr] Compiling ansi_term v0.11.0 [INFO] [stderr] Compiling nom v5.1.2 [INFO] [stderr] Compiling log v0.4.14 [INFO] [stderr] Compiling strsim v0.8.0 [INFO] [stderr] Compiling lazycell v1.3.0 [INFO] [stderr] Compiling textwrap v0.11.0 [INFO] [stderr] Compiling libloading v0.7.0 [INFO] [stderr] Compiling cc v1.0.68 [INFO] [stderr] Compiling peeking_take_while v0.1.2 [INFO] [stderr] Compiling rustc-hash v1.1.0 [INFO] [stderr] Compiling lazy_static v1.4.0 [INFO] [stderr] Compiling shlex v1.0.0 [INFO] [stderr] Compiling clang-sys v1.2.0 [INFO] [stderr] Compiling aho-corasick v0.7.18 [INFO] [stderr] Compiling quote v1.0.9 [INFO] [stderr] Compiling cmake v0.1.45 [INFO] [stderr] Compiling atty v0.2.14 [INFO] [stderr] Compiling which v3.1.1 [INFO] [stderr] Compiling clap v2.33.3 [INFO] [stderr] Compiling regex v1.5.4 [INFO] [stderr] Compiling cexpr v0.4.0 [INFO] [stderr] Compiling env_logger v0.8.4 [INFO] [stderr] Compiling rustovio v0.1.0 (/opt/rustwide/workdir) [INFO] [stderr] error: failed to run custom build command for `rustovio v0.1.0 (/opt/rustwide/workdir)` [INFO] [stderr] note: To improve backtraces for build dependencies, set the CARGO_PROFILE_DEV_BUILD_OVERRIDE_DEBUG=true environment variable to enable debug information generation. [INFO] [stderr] [INFO] [stderr] Caused by: [INFO] [stderr] process didn't exit successfully: `/opt/rustwide/target/debug/build/rustovio-9563a85666df2046/build-script-build` (exit status: 101) [INFO] [stderr] --- stdout [INFO] [stderr] running: cd "/opt/rustwide/target/debug/build/rustovio-1cdf46600b81d39b/out/build" && CMAKE_PREFIX_PATH="" "cmake" "/opt/rustwide/workdir/verovio/cmake" "-DBUILD_AS_WASM=ON" "-DCMAKE_INSTALL_PREFIX=/opt/rustwide/target/debug/build/rustovio-1cdf46600b81d39b/out" "-DCMAKE_C_FLAGS= -ffunction-sections -fdata-sections -fPIC -m64" "-DCMAKE_C_COMPILER=/usr/bin/cc" "-DCMAKE_CXX_FLAGS= -ffunction-sections -fdata-sections -fPIC -m64" "-DCMAKE_CXX_COMPILER=/usr/bin/c++" "-DCMAKE_ASM_FLAGS= -ffunction-sections -fdata-sections -fPIC -m64" "-DCMAKE_ASM_COMPILER=/usr/bin/cc" "-DCMAKE_BUILD_TYPE=Debug" [INFO] [stderr] -- The C compiler identification is GNU 13.3.0 [INFO] [stderr] -- The CXX compiler identification is GNU 13.3.0 [INFO] [stderr] -- Detecting C compiler ABI info [INFO] [stderr] -- Detecting C compiler ABI info - done [INFO] [stderr] -- Check for working C compiler: /usr/bin/cc - skipped [INFO] [stderr] -- Detecting C compile features [INFO] [stderr] -- Detecting C compile features - done [INFO] [stderr] -- Detecting CXX compiler ABI info [INFO] [stderr] -- Detecting CXX compiler ABI info - done [INFO] [stderr] -- Check for working CXX compiler: /usr/bin/c++ - skipped [INFO] [stderr] -- Detecting CXX compile features [INFO] [stderr] -- Detecting CXX compile features - done [INFO] [stderr] -- Enabling debug information [INFO] [stderr] -- ***** Building Verovio as WASM BC ***** [INFO] [stderr] -- Configuring done (0.8s) [INFO] [stderr] -- Generating done (0.0s) [INFO] [stderr] -- Build files have been written to: /opt/rustwide/target/debug/build/rustovio-1cdf46600b81d39b/out/build [INFO] [stderr] running: cd "/opt/rustwide/target/debug/build/rustovio-1cdf46600b81d39b/out/build" && MAKEFLAGS="-j --jobserver-fds=8,9 --jobserver-auth=8,9" "cmake" "--build" "." "--config" "Debug" "--" [INFO] [stderr] [ 1%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/anchoredtext.cpp.o [INFO] [stderr] [ 1%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/tools/c_wrapper.cpp.o [INFO] [stderr] [ 1%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/annot.cpp.o [INFO] [stderr] [ 1%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/beam.cpp.o [INFO] [stderr] [ 2%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/app.cpp.o [INFO] [stderr] [ 3%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/bboxdevicecontext.cpp.o [INFO] [stderr] [ 3%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/boundary.cpp.o [INFO] [stderr] [ 4%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/arpeg.cpp.o [INFO] [stderr] [ 4%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/areaposinterface.cpp.o [INFO] [stderr] [ 4%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/artic.cpp.o [INFO] [stderr] [ 1%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/barline.cpp.o [INFO] [stderr] [ 5%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/att.cpp.o [INFO] [stderr] [ 6%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/add.cpp.o [INFO] [stderr] [ 6%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/abbr.cpp.o [INFO] [stderr] [ 6%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/accid.cpp.o [INFO] [stderr] [ 7%] Building CXX object CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/beatrpt.cpp.o [INFO] [stderr] [INFO] [stderr] --- stderr [INFO] [stderr] fatal: not a git repository (or any parent up to mount point /opt/rustwide) [INFO] [stderr] Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set). [INFO] [stderr] ../tools/get_git_commit.sh: 12: cannot create ./include/vrv/git_commit.h: Read-only file system [INFO] [stderr] ../tools/get_git_commit.sh: 13: cannot create ./include/vrv/git_commit.h: Read-only file system [INFO] [stderr] ../tools/get_git_commit.sh: 14: cannot create ./include/vrv/git_commit.h: Read-only file system [INFO] [stderr] ../tools/get_git_commit.sh: 15: cannot create ./include/vrv/git_commit.h: Read-only file system [INFO] [stderr] ../tools/get_git_commit.sh: 16: cannot create ./include/vrv/git_commit.h: Read-only file system [INFO] [stderr] ../tools/get_git_commit.sh: 17: cannot create ./include/vrv/git_commit.h: Read-only file system [INFO] [stderr] CMake Warning: [INFO] [stderr] Manually-specified variables were not used by the project: [INFO] [stderr] [INFO] [stderr] CMAKE_ASM_COMPILER [INFO] [stderr] CMAKE_ASM_FLAGS [INFO] [stderr] [INFO] [stderr] [INFO] [stderr] c++: fatal error: Killed signal terminated program cc1plus [INFO] [stderr] compilation terminated. [INFO] [stderr] gmake[2]: *** [CMakeFiles/verovio.dir/build.make:272: CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/beatrpt.cpp.o] Error 1 [INFO] [stderr] gmake[2]: *** Waiting for unfinished jobs.... [INFO] [stderr] c++: fatal error: Killed signal terminated program cc1plus [INFO] [stderr] compilation terminated. [INFO] [stderr] gmake[2]: *** [CMakeFiles/verovio.dir/build.make:258: CMakeFiles/verovio.dir/opt/rustwide/workdir/verovio/src/beam.cpp.o] Error 1 [INFO] [stderr] gmake[1]: *** [CMakeFiles/Makefile2:110: CMakeFiles/verovio.dir/all] Error 2 [INFO] [stderr] gmake: *** [Makefile:136: all] Error 2 [INFO] [stderr] [INFO] [stderr] thread 'main' (680) panicked at /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/cmake-0.1.45/src/lib.rs:894:5: [INFO] [stderr] [INFO] [stderr] command did not execute successfully, got: exit status: 2 [INFO] [stderr] [INFO] [stderr] build script failed, must exit now [INFO] [stderr] stack backtrace: [INFO] [stderr] 0: 0x5680eb70b942 - std::backtrace_rs::backtrace::libunwind::trace::h7cddb8376417e7cc [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/../../backtrace/src/backtrace/libunwind.rs:117:9 [INFO] [stderr] 1: 0x5680eb70b942 - std::backtrace_rs::backtrace::trace_unsynchronized::hb4e41acf4b349ff1 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/../../backtrace/src/backtrace/mod.rs:66:14 [INFO] [stderr] 2: 0x5680eb70b942 - std::sys::backtrace::_print_fmt::h1222b80910ba6eb5 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/sys/backtrace.rs:66:9 [INFO] [stderr] 3: 0x5680eb70b942 - ::fmt::h5bb8a979ba5db788 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/sys/backtrace.rs:39:26 [INFO] [stderr] 4: 0x5680eb71d44f - core::fmt::rt::Argument::fmt::h2ee2c138a50a7796 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/core/src/fmt/rt.rs:173:76 [INFO] [stderr] 5: 0x5680eb71d44f - core::fmt::write::h1e0dbf07fe3990bd [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/core/src/fmt/mod.rs:1468:25 [INFO] [stderr] 6: 0x5680eb6dadf3 - std::io::default_write_fmt::hb0810a37865e52a5 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/io/mod.rs:639:11 [INFO] [stderr] 7: 0x5680eb6dadf3 - std::io::Write::write_fmt::h12c8908aaac7ca22 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/io/mod.rs:1954:13 [INFO] [stderr] 8: 0x5680eb6e61e2 - std::sys::backtrace::BacktraceLock::print::h788d486777205086 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/sys/backtrace.rs:42:9 [INFO] [stderr] 9: 0x5680eb6e91af - std::panicking::default_hook::{{closure}}::ha7bdfeb5949fc0fa [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/panicking.rs:301:27 [INFO] [stderr] 10: 0x5680eb6e9009 - std::panicking::default_hook::h6dad75ec721846f4 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/panicking.rs:328:9 [INFO] [stderr] 11: 0x5680eb6e9785 - std::panicking::panic_with_hook::hba00e869ada17676 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/panicking.rs:834:13 [INFO] [stderr] 12: 0x5680eb6e961a - std::panicking::panic_handler::{{closure}}::h3d21149c258e5ceb [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/panicking.rs:707:13 [INFO] [stderr] 13: 0x5680eb6e6319 - std::sys::backtrace::__rust_end_short_backtrace::h4f5d9b9dfb3e6ec1 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/sys/backtrace.rs:174:18 [INFO] [stderr] 14: 0x5680eb6cebbd - __rustc[9a7a9f9af7564de1]::rust_begin_unwind [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/panicking.rs:698:5 [INFO] [stderr] 15: 0x5680eb727510 - core::panicking::panic_fmt::h78e817a90331d98b [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/core/src/panicking.rs:75:14 [INFO] [stderr] 16: 0x5680eb68762b - cmake::fail::h7d3d1e9bd3c1ab8c [INFO] [stderr] 17: 0x5680eb6872ea - cmake::run::h67384bbc8eb138dc [INFO] [stderr] 18: 0x5680eb68c14d - cmake::Config::build::hf6c41a77949dfe24 [INFO] [stderr] 19: 0x5680eb3128c9 - build_script_build::main::h0978e977744458bd [INFO] [stderr] 20: 0x5680eb313673 - core::ops::function::FnOnce::call_once::hc6c0cca30fd90561 [INFO] [stderr] 21: 0x5680eb3135b6 - std::sys::backtrace::__rust_begin_short_backtrace::h27cc2e27e9281d3f [INFO] [stderr] 22: 0x5680eb313539 - std::rt::lang_start::{{closure}}::hde59b57eef3452d8 [INFO] [stderr] 23: 0x5680eb6dc810 - core::ops::function::impls:: for &F>::call_once::h1dc0a50e6295ec78 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/core/src/ops/function.rs:290:21 [INFO] [stderr] 24: 0x5680eb6dc810 - std::panicking::catch_unwind::do_call::h209f742e9999044e [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/panicking.rs:590:40 [INFO] [stderr] 25: 0x5680eb6dc810 - std::panicking::catch_unwind::h508c6e2aa6d72749 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/panicking.rs:553:19 [INFO] [stderr] 26: 0x5680eb6dc810 - std::panic::catch_unwind::hebcbb24aa9914693 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/panic.rs:359:14 [INFO] [stderr] 27: 0x5680eb6dc810 - std::rt::lang_start_internal::{{closure}}::h703cbe32967ef209 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/rt.rs:175:24 [INFO] [stderr] 28: 0x5680eb6dc810 - std::panicking::catch_unwind::do_call::hf50f2a30bce4e10b [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/panicking.rs:590:40 [INFO] [stderr] 29: 0x5680eb6dc810 - std::panicking::catch_unwind::hac448d7e3b12daa3 [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/panicking.rs:553:19 [INFO] [stderr] 30: 0x5680eb6dc810 - std::panic::catch_unwind::ha9d74a13d77f299c [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/panic.rs:359:14 [INFO] [stderr] 31: 0x5680eb6dc810 - std::rt::lang_start_internal::ha26d244788d1956d [INFO] [stderr] at /rustc/cdb45c87e2cd43495379f7e867e3cc15dcee9f93/library/std/src/rt.rs:171:5 [INFO] [stderr] 32: 0x5680eb313521 - std::rt::lang_start::h38a704520b9a96c3 [INFO] [stderr] 33: 0x5680eb314fe5 - main [INFO] [stderr] 34: 0x7065972281ca - [INFO] [stderr] 35: 0x70659722828b - __libc_start_main [INFO] [stderr] 36: 0x5680eb3125b5 - _start [INFO] [stderr] 37: 0x0 - [INFO] running `Command { std: "docker" "inspect" "44035ddebc81fd5064724bece9b62d752999368ea10fa6280ec18c8f5190927a", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "44035ddebc81fd5064724bece9b62d752999368ea10fa6280ec18c8f5190927a", kill_on_drop: false }` [INFO] [stdout] 44035ddebc81fd5064724bece9b62d752999368ea10fa6280ec18c8f5190927a