Closed
Description
Currently the cross-compile assistance does not set any env vars in this branch:
libcnb.rs/libcnb-package/src/cross_compile.rs
Lines 49 to 53 in 4ec39b6
Whilst some compiles will succeed with that implementation (since Rust will automatically use musl-gcc if it's found), it breaks when cross-compiling for a different architecture.
All musl-gcc does is compile using musl rather than glibc, using the same architecture as the host. (As opposed to the wrappers like x86_64-unknown-linux-musl which also target the different architecture.)
In addition, since none of the CC_* type env vars are set, if the buildpack uses any Rust dependencies that contain C components (such as the ring crate used for TLS), then the build will fail like so:
The following warnings were emitted during compilation:
warning: cc1: error: unrecognized command-line option '-m64'
error: failed to run custom build command for `libz-sys v1.1.12`
Caused by:
process didn't exit successfully: `/buildpacks-python/target/debug/build/libz-sys-bfd25c9fd11b1325/build-script-build` (exit status: 1)
--- stdout
cargo:rerun-if-env-changed=LIBZ_SYS_STATIC
cargo:rerun-if-changed=build.rs
cargo:rerun-if-env-changed=ZLIB_NO_PKG_CONFIG
cargo:rerun-if-env-changed=PKG_CONFIG_ALLOW_CROSS_x86_64-unknown-linux-musl
cargo:rerun-if-env-changed=PKG_CONFIG_ALLOW_CROSS_x86_64_unknown_linux_musl
cargo:rerun-if-env-changed=TARGET_PKG_CONFIG_ALLOW_CROSS
cargo:rerun-if-env-changed=PKG_CONFIG_ALLOW_CROSS
cargo:rerun-if-env-changed=PKG_CONFIG_x86_64-unknown-linux-musl
cargo:rerun-if-env-changed=PKG_CONFIG_x86_64_unknown_linux_musl
cargo:rerun-if-env-changed=TARGET_PKG_CONFIG
cargo:rerun-if-env-changed=PKG_CONFIG
cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64-unknown-linux-musl
cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64_unknown_linux_musl
cargo:rerun-if-env-changed=TARGET_PKG_CONFIG_SYSROOT_DIR
cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR
cargo-warning=pkg-config has not been configured to support cross-compilation.
Install a sysroot for the target platform and configure it via
PKG_CONFIG_SYSROOT_DIR and PKG_CONFIG_PATH, or install a
cross-compiling wrapper for pkg-config and set it via
PKG_CONFIG environment variable.
TARGET = Some("x86_64-unknown-linux-musl")
OPT_LEVEL = Some("0")
HOST = Some("aarch64-unknown-linux-gnu")
cargo:rerun-if-env-changed=CC_x86_64-unknown-linux-musl
CC_x86_64-unknown-linux-musl = None
cargo:rerun-if-env-changed=CC_x86_64_unknown_linux_musl
CC_x86_64_unknown_linux_musl = None
cargo:rerun-if-env-changed=TARGET_CC
TARGET_CC = None
cargo:rerun-if-env-changed=CC
CC = None
RUSTC_LINKER = None
cargo:rerun-if-env-changed=CROSS_COMPILE
CROSS_COMPILE = None
cargo:rerun-if-env-changed=CRATE_CC_NO_DEFAULTS
CRATE_CC_NO_DEFAULTS = None
DEBUG = Some("false")
CARGO_CFG_TARGET_FEATURE = Some("fxsr,sse,sse2")
cargo:rerun-if-env-changed=CFLAGS_x86_64-unknown-linux-musl
CFLAGS_x86_64-unknown-linux-musl = None
cargo:rerun-if-env-changed=CFLAGS_x86_64_unknown_linux_musl
CFLAGS_x86_64_unknown_linux_musl = None
cargo:rerun-if-env-changed=TARGET_CFLAGS
TARGET_CFLAGS = None
cargo:rerun-if-env-changed=CFLAGS
CFLAGS = None
running: "musl-gcc" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-I" "src/zlib" "-fvisibility=hidden" "-DZ_SOLO" "-DSTDC" "-D_LARGEFILE64_SOURCE" "-D_POSIX_SOURCE" "-o" "/buildpacks-python/target/x86_64-unknown-linux-musl/debug/build/libz-sys-672d486ba2008913/out/lib/src/zlib/adler32.o" "-c" "src/zlib/adler32.c"
cargo:warning=cc1: error: unrecognized command-line option '-m64'
exit status: 1
--- stderr
error occurred: Command "musl-gcc" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-I" "src/zlib" "-fvisibility=hidden" "-DZ_SOLO" "-DSTDC" "-D_LARGEFILE64_SOURCE" "-D_POSIX_SOURCE" "-o" "/buildpacks-python/target/x86_64-unknown-linux-musl/debug/build/libz-sys-672d486ba2008913/out/lib/src/zlib/adler32.o" "-c" "src/zlib/adler32.c" with args "musl-gcc" did not execute successfully (status code exit status: 1).