Error building dependencies with a custom `build.rs` script

Hi, I'm trying to build a Cargo workspace which depends on the ring crate. This crate has a custom build.rs script, and my Yocto build fails with the following output:

|   CC = Some(/home/builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/wrappers/cc-wrapper.sh)                                     [7/1944]
|   RUSTC_WRAPPER = None
|   cargo:rerun-if-env-changed=CC_ENABLE_DEBUG_OUTPUT
|   cargo:rerun-if-env-changed=CRATE_CC_NO_DEFAULTS
|   CRATE_CC_NO_DEFAULTS = None
|   DEBUG = Some(true)
|   CARGO_CFG_TARGET_FEATURE = Some(fxsr,sse,sse2)
|   cargo:rerun-if-env-changed=CFLAGS
|   CFLAGS = Some( -O2 -pipe -g -feliminate-unused-debug-types -fcanon-prefix-map  -fmacro-prefix-map=/home/builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-
flight-software/git/git=/usr/src/debug/cybeesat-flight-software/git  -fdebug-prefix-map=/home/builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-softwar
e/git/git=/usr/src/debug/cybeesat-flight-software/git  -fmacro-prefix-map=/home/builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/target=/
usr/src/debug/cybeesat-flight-software/git  -fdebug-prefix-map=/home/builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/target=/usr/src/deb
ug/cybeesat-flight-software/git  -fdebug-prefix-map=/home/builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/recipe-sysroot=  -fmacro-prefi
x-map=/home/builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/recipe-sysroot=  -fdebug-prefix-map=/home/builder/cybeesat/build/tmp/work/co
rtexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/recipe-sysroot-native= )
|   cargo:rerun-if-env-changed=CC_SHELL_ESCAPED_FLAGS
|   CC_SHELL_ESCAPED_FLAGS = None
|   cargo:rerun-if-env-changed=HOST_CFLAGS
|   HOST_CFLAGS = Some()
|   cargo:rerun-if-env-changed=CFLAGS_x86_64_unknown_linux_gnu
|   CFLAGS_x86_64_unknown_linux_gnu = None
|   cargo:rerun-if-env-changed=CFLAGS_x86_64-unknown-linux-gnu
|   CFLAGS_x86_64-unknown-linux-gnu = None
|   CARGO_ENCODED_RUSTFLAGS = Some()
|   cargo:warning=arm-poky-linux-gnueabi-gcc: error: unrecognized command-line option '-m64'
|
|   --- stderr
|
|
|   error occurred in cc-rs: command did not execute successfully (status code exit status: 1): LC_ALL="C" "/home/builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cyb
eesat-flight-software/git/wrappers/cc-wrapper.sh" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "/home/builder/cybeesat/build/tmp/work
/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/cargo_home/registry/src/index.crates.io-1949cf8c6b5b557f/ring-0.17.14/include" "-I" "/home/builder/cybeesat/build/tmp/w
ork/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/cargo_home/registry/src/index.crates.io-1949cf8c6b5b557f/ring-0.17.14/pregenerated" "-fvisibility=hidden" "-std=c1x"
 "-Wall" "-Wbad-function-cast" "-Wcast-align" "-Wcast-qual" "-Wconversion" "-Wmissing-field-initializers" "-Wmissing-include-dirs" "-Wnested-externs" "-Wredundant-decls" "-Wshadow" "-Wsign-com
pare" "-Wsign-conversion" "-Wstrict-prototypes" "-Wundef" "-Wuninitialized" "-g3" "-DNDEBUG" "-O2" "-pipe" "-g" "-feliminate-unused-debug-types" "-fcanon-prefix-map" "-fmacro-prefix-map=/home/
builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/git=/usr/src/debug/cybeesat-flight-software/git" "-fdebug-prefix-map=/home/builder/cybee
sat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/git=/usr/src/debug/cybeesat-flight-software/git" "-fmacro-prefix-map=/home/builder/cybeesat/build/tmp
/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/target=/usr/src/debug/cybeesat-flight-software/git" "-fdebug-prefix-map=/home/builder/cybeesat/build/tmp/work/cort
exa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/target=/usr/src/debug/cybeesat-flight-software/git" "-fdebug-prefix-map=/home/builder/cybeesat/build/tmp/work/cortexa5t2hf-n
eon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/recipe-sysroot=" "-fmacro-prefix-map=/home/builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-
software/git/recipe-sysroot=" "-fdebug-prefix-map=/home/builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/recipe-sysroot-native=" "-o" "/h
ome/builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/target/release/build/ring-b223ecc4d5a766a0/out/25ac62e5b3c53843-curve25519.o" "-c" "
/home/builder/cybeesat/build/tmp/work/cortexa5t2hf-neon-vfpv4-poky-linux-gnueabi/cybeesat-flight-software/git/cargo_home/registry/src/index.crates.io-1949cf8c6b5b557f/ring-0.17.14/crypto/curve
25519/curve25519.c"

My recipe is very simple:

SUMMARY = "CyBEEsat Flight Software"
HOMEPAGE = "https://gitlab.com/rccn/missions/cybeesat/"
LICENSE = "GPL"

inherit cargo_bin

# Enable network for the compile task allowing cargo to download dependencies
do_compile[network] = "1"

SRC_URI = "gitsm://gitlab.com/rccn/missions/cybeesat.git;protocol=https;branch=main"
SRCREV="3db10d6228be6452fad99c0cd8c336d2e42331ee"
S = "${WORKDIR}/git"
LIC_FILES_CHKSUM = "file://LICENSE;md5=79409ca9a2f1e5e21d07bb10c0f5c7b7"

I'm not sure if this is a general problem when building build scripts (which are compiled for the host architecture), something specific to my setup, or something else entirely. Any help would be greatly appreciated. Thanks!

Start with the provided Yocto recipe and the ring crate's build.rs, then inspect the Cargo build invocation around cc-rs and the target settings. Reproduce the failure for the stated ARM target; done means the workspace builds successfully without the compiler receiving an incompatible -m64 option.