Cross-compilation failure: aws-lc-sys uses wrong linker despite correct environment variables

[brndnmtthws]

Summary

Cross-compiling static musl binaries that include aws-lc-rs fails during the aws-lc-sys build process. The build script uses incompatible host libraries with the target linker, despite correct cross-compilation environment setup.

Environment

• aws-lc-sys version: v0.29.0
• Host: x86_64-unknown-linux-gnu
• Target: aarch64-unknown-linux-musl
• Toolchain: Nix with clang cross-compilation setup

Problem Description

I'm trying to cross-compile static musl binaries that include aws-lc-rs. A build-time test is failing when building aws-lc-sys, blocking the build. The failure appears to be caused by aws-lc-sys using incompatible libraries during linking.

The environment is properly configured with target-specific compilers and linkers:

• CC_aarch64-unknown-linux-musl: /nix/store/.../aarch64-unknown-linux-musl-cc
• CXX_aarch64-unknown-linux-musl: /nix/store/.../aarch64-unknown-linux-musl-c++
• CARGO_TARGET_AARCH64_UNKNOWN_LINUX_MUSL_LINKER: /nix/store/.../aarch64-unknown-linux-musl-ld

However, the build fails with linker errors indicating aws-lc-sys is attempting to link against incompatible host libraries.

Error Details

error: failed to run custom build command for `aws-lc-sys v0.29.0`
...
thread 'main' panicked at aws-lc-sys-0.29.0/builder/cc_builder.rs:471:9:
...
/nix/store/.../aarch64-unknown-linux-musl-ld: skipping incompatible .../libgcc_s.so.1 when searching for libgcc_s.so.1
/nix/store/.../aarch64-unknown-linux-musl-ld: cannot find libgcc_s.so.1: No such file or directory
clang: error: linker command failed with exit code 1

The logs show that aws-lc-sys correctly detects and uses the target-specific compilers, but the linking phase fails because it's searching for host architecture libraries that are incompatible with the aarch64 target.

Reproduction Steps

I've created a minimal reproduction case that demonstrates this cross-compilation issue.

Prerequisites

• Nix package manager

Reproduce the Issue

# Download the reproduction environment
curl -O https://gist.githubusercontent.com/brndnmtthws/c5c5ae64b538703ac7eb8425afb7f069/raw/flake.nix

# Enter the environment and run the reproducer
nix develop
reproduce-issue

Expected Result

The build should fail with aws-lc-sys linker errors:

error: failed to run custom build command for `aws-lc-sys v0.29.0`
...
/nix/store/.../aarch64-unknown-linux-musl-ld: cannot find libgcc_s.so.1: No such file or directory
clang: error: linker command failed with exit code 1

Root Cause

The issue appears to be that aws-lc-sys's build script doesn't properly configure library search paths for cross-compilation. While it correctly uses target-specific compilers, the linker searches for libraries in locations that contain host-architecture binaries incompatible with the target.

Proposed Solutions

Short-term

• Environment variable support: Add support for target-specific library path configuration
• Better error handling: Provide clearer error messages when cross-compilation library paths are misconfigured

Long-term

System library support: Unlike many other -sys crates, aws-lc-sys doesn't appear to support linking against pre-built system libraries. Adding support for:

• AWS_LC_SYS_USE_SYSTEM_LIB environment variable
• pkg-config integration for system AWS-LC installations
• Static library path specification via environment variable

This would enable:

1. Building AWS-LC once with the package manager using proper cross-compilation
2. Reusing cached builds across multiple Rust projects
3. Avoiding repeated compilation and linking issues

Impact

This issue significantly affects cross-compilation workflows, particularly in Nix environments where reproducible builds and dependency caching are essential. The current behavior forces rebuilding AWS-LC for every project and makes cross-compilation unreliable.

Full build log

warning: aws-lc-sys@0.29.0: Building with: CC
warning: aws-lc-sys@0.29.0: Symbol Prefix: Some("aws_lc_0_29_0")
warning: aws-lc-sys@0.29.0: Compilation of 'c11.c' succeeded - Ok(["/tmp/nix-build-atlas-release-deps-0.3.4.drv-0/source/target/aarch64-unknown-linux-musl/release/build/aws-lc-sys-99f44b0176b6a8ac/out/out-c11/e89dd77a48967ab8-c11.o"]).
warning: aws-lc-sys@0.29.0: Environment Variable found 'CC_aarch64-unknown-linux-musl': '/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-cc'
warning: aws-lc-sys@0.29.0: Environment Variable found 'CC': 'gcc'
warning: aws-lc-sys@0.29.0: Setting CC_aarch64_unknown_linux_musl: /nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-cc
warning: aws-lc-sys@0.29.0: Environment Variable found 'CXX_aarch64-unknown-linux-musl': '/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-c++'
warning: aws-lc-sys@0.29.0: Environment Variable found 'CXX': 'g++'
warning: aws-lc-sys@0.29.0: Setting CXX_aarch64_unknown_linux_musl: /nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-c++
warning: aws-lc-sys@0.29.0: Using flag: -ffile-prefix-map=/nix/store/sm08wq5phnhfz524q8bcbn23rvlfjkvb-cargo-package-aws-lc-sys-0.29.0=
warning: aws-lc-sys@0.29.0: Compilation of 'stdalign_check.c' succeeded - Ok(["/tmp/nix-build-atlas-release-deps-0.3.4.drv-0/source/target/aarch64-unknown-linux-musl/release/build/aws-lc-sys-99f44b0176b6a8ac/out/out-stdalign_check/e89dd77a48967ab8-stdalign_check.o"]).
warning: aws-lc-sys@0.29.0: Compilation of 'builtin_swap_check.c' succeeded - Ok(["/tmp/nix-build-atlas-release-deps-0.3.4.drv-0/source/target/aarch64-unknown-linux-musl/release/build/aws-lc-sys-99f44b0176b6a8ac/out/out-builtin_swap_check/e89dd77a48967ab8-builtin_swap_check.o"]).
error: failed to run custom build command for `aws-lc-sys v0.29.0`
Caused by:
  process didn't exit successfully: `/tmp/nix-build-atlas-release-deps-0.3.4.drv-0/source/target/release/build/aws-lc-sys-1268969f35b6892b/build-script-main` (exit status: 101)
  --- stdout
  cargo:rerun-if-env-changed=AWS_LC_SYS_NO_PREFIX_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_NO_PREFIX
  cargo:rerun-if-env-changed=AWS_LC_SYS_PREGENERATING_BINDINGS_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_PREGENERATING_BINDINGS
  cargo:rerun-if-env-changed=AWS_LC_SYS_EXTERNAL_BINDGEN_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_EXTERNAL_BINDGEN
  cargo:rerun-if-env-changed=AWS_LC_SYS_NO_ASM_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_NO_ASM
  cargo:rerun-if-env-changed=AWS_LC_SYS_CFLAGS_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_CFLAGS
  cargo:rerun-if-env-changed=CFLAGS_aarch64-unknown-linux-musl
  cargo:rerun-if-env-changed=CFLAGS
  cargo:rerun-if-env-changed=AWS_LC_SYS_PREBUILT_NASM_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_PREBUILT_NASM
  cargo:rerun-if-env-changed=AWS_LC_SYS_C_STD_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_C_STD
  cargo:rerun-if-env-changed=AWS_LC_SYS_CMAKE_BUILDER_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_CMAKE_BUILDER
  cargo:rerun-if-env-changed=AWS_LC_SYS_NO_PREGENERATED_SRC_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_NO_PREGENERATED_SRC
  cargo:rerun-if-env-changed=AWS_LC_SYS_EFFECTIVE_TARGET_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_EFFECTIVE_TARGET
  cargo:rustc-cfg=aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_STATIC_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_STATIC
  default_for Target: 'aarch64-unknown-linux-musl'
  cargo:rerun-if-env-changed=CARGO_FEATURE_SSL
  cargo:warning=Building with: CC
  cargo:warning=Symbol Prefix: Some("aws_lc_0_29_0")
  default_for Target: 'aarch64-unknown-linux-musl'
  cargo:rerun-if-env-changed=CARGO_FEATURE_SSL
  cargo:root=/tmp/nix-build-atlas-release-deps-0.3.4.drv-0/source/target/aarch64-unknown-linux-musl/release/build/aws-lc-sys-99f44b0176b6a8ac/out
  default_for Target: 'aarch64-unknown-linux-musl'
  OPT_LEVEL = Some(3)
  OUT_DIR = Some(/tmp/nix-build-atlas-release-deps-0.3.4.drv-0/source/target/aarch64-unknown-linux-musl/release/build/aws-lc-sys-99f44b0176b6a8ac/out)
  TARGET = Some(aarch64-unknown-linux-musl)
  HOST = Some(x86_64-unknown-linux-gnu)
  cargo:rerun-if-env-changed=CC_aarch64-unknown-linux-musl
  CC_aarch64-unknown-linux-musl = Some(/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-cc)
  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(false)
  cargo:rerun-if-env-changed=CFLAGS
  CFLAGS = None
  cargo:rerun-if-env-changed=TARGET_CFLAGS
  TARGET_CFLAGS = None
  cargo:rerun-if-env-changed=CFLAGS_aarch64_unknown_linux_musl
  CFLAGS_aarch64_unknown_linux_musl = None
  cargo:rerun-if-env-changed=CFLAGS_aarch64-unknown-linux-musl
  CFLAGS_aarch64-unknown-linux-musl = None
  CARGO_ENCODED_RUSTFLAGS = Some(-Clinker=/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-ld-L/nix/store/qjcach3bzi6390xs5gw3grivhmls6yn0-libcxx-static-aarch64-unknown-linux-musl-19.1.7/lib-lc++-lc++abi-luring-L/nix/store/21nnvj4vjci5y5ynwr9b09dlnfycz2kg-liburing-static-aarch64-unknown-linux-musl-2.9/lib-Clink-arg=-static-Ctarget-feature=+crt-static)
  OPT_LEVEL = Some(3)
  TARGET = Some(aarch64-unknown-linux-musl)
  HOST = Some(x86_64-unknown-linux-gnu)
  cargo:rerun-if-env-changed=CC_aarch64-unknown-linux-musl
  CC_aarch64-unknown-linux-musl = Some(/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-cc)
  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(false)
  cargo:rerun-if-env-changed=CFLAGS
  CFLAGS = None
  cargo:rerun-if-env-changed=TARGET_CFLAGS
  TARGET_CFLAGS = None
  cargo:rerun-if-env-changed=CFLAGS_aarch64_unknown_linux_musl
  CFLAGS_aarch64_unknown_linux_musl = None
  cargo:rerun-if-env-changed=CFLAGS_aarch64-unknown-linux-musl
  CFLAGS_aarch64-unknown-linux-musl = None
  CARGO_ENCODED_RUSTFLAGS = Some(-Clinker=/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-ld-L/nix/store/qjcach3bzi6390xs5gw3grivhmls6yn0-libcxx-static-aarch64-unknown-linux-musl-19.1.7/lib-lc++-lc++abi-luring-L/nix/store/21nnvj4vjci5y5ynwr9b09dlnfycz2kg-liburing-static-aarch64-unknown-linux-musl-2.9/lib-Clink-arg=-static-Ctarget-feature=+crt-static)
  cargo:warning=Compilation of 'c11.c' succeeded - Ok(["/tmp/nix-build-atlas-release-deps-0.3.4.drv-0/source/target/aarch64-unknown-linux-musl/release/build/aws-lc-sys-99f44b0176b6a8ac/out/out-c11/e89dd77a48967ab8-c11.o"]).
  cargo:rerun-if-env-changed=AWS_LC_SYS_CC_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_CC
  cargo:rerun-if-env-changed=CC_aarch64-unknown-linux-musl
  cargo:warning=Environment Variable found 'CC_aarch64-unknown-linux-musl': '/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-cc'
  cargo:rerun-if-env-changed=CC
  cargo:warning=Environment Variable found 'CC': 'gcc'
  cargo:warning=Setting CC_aarch64_unknown_linux_musl: /nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-cc
  cargo:rerun-if-env-changed=AWS_LC_SYS_CXX_aarch64_unknown_linux_musl
  cargo:rerun-if-env-changed=AWS_LC_SYS_CXX
  cargo:rerun-if-env-changed=CXX_aarch64-unknown-linux-musl
  cargo:warning=Environment Variable found 'CXX_aarch64-unknown-linux-musl': '/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-c++'
  cargo:rerun-if-env-changed=CXX
  cargo:warning=Environment Variable found 'CXX': 'g++'
  cargo:warning=Setting CXX_aarch64_unknown_linux_musl: /nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-c++
  OUT_DIR = Some(/tmp/nix-build-atlas-release-deps-0.3.4.drv-0/source/target/aarch64-unknown-linux-musl/release/build/aws-lc-sys-99f44b0176b6a8ac/out)
  cargo:rerun-if-env-changed=CC_ENABLE_DEBUG_OUTPUT
  cargo:rerun-if-env-changed=CRATE_CC_NO_DEFAULTS
  CRATE_CC_NO_DEFAULTS = None
  TARGET = Some(aarch64-unknown-linux-musl)
  HOST = Some(x86_64-unknown-linux-gnu)
  cargo:rerun-if-env-changed=CFLAGS
  CFLAGS = None
  cargo:rerun-if-env-changed=TARGET_CFLAGS
  TARGET_CFLAGS = None
  cargo:rerun-if-env-changed=CFLAGS_aarch64_unknown_linux_musl
  CFLAGS_aarch64_unknown_linux_musl = None
  cargo:rerun-if-env-changed=CFLAGS_aarch64-unknown-linux-musl
  CFLAGS_aarch64-unknown-linux-musl = None
  cargo:warning=Using flag: -ffile-prefix-map=/nix/store/sm08wq5phnhfz524q8bcbn23rvlfjkvb-cargo-package-aws-lc-sys-0.29.0=
  OPT_LEVEL = Some(3)
  TARGET = Some(aarch64-unknown-linux-musl)
  HOST = Some(x86_64-unknown-linux-gnu)
  cargo:rerun-if-env-changed=CC_aarch64-unknown-linux-musl
  CC_aarch64-unknown-linux-musl = Some(/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-cc)
  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(false)
  cargo:rerun-if-env-changed=CFLAGS
  CFLAGS = None
  cargo:rerun-if-env-changed=TARGET_CFLAGS
  TARGET_CFLAGS = None
  cargo:rerun-if-env-changed=CFLAGS_aarch64_unknown_linux_musl
  CFLAGS_aarch64_unknown_linux_musl = None
  cargo:rerun-if-env-changed=CFLAGS_aarch64-unknown-linux-musl
  CFLAGS_aarch64-unknown-linux-musl = None
  CARGO_ENCODED_RUSTFLAGS = Some(-Clinker=/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-ld-L/nix/store/qjcach3bzi6390xs5gw3grivhmls6yn0-libcxx-static-aarch64-unknown-linux-musl-19.1.7/lib-lc++-lc++abi-luring-L/nix/store/21nnvj4vjci5y5ynwr9b09dlnfycz2kg-liburing-static-aarch64-unknown-linux-musl-2.9/lib-Clink-arg=-static-Ctarget-feature=+crt-static)
  cargo:warning=Compilation of 'stdalign_check.c' succeeded - Ok(["/tmp/nix-build-atlas-release-deps-0.3.4.drv-0/source/target/aarch64-unknown-linux-musl/release/build/aws-lc-sys-99f44b0176b6a8ac/out/out-stdalign_check/e89dd77a48967ab8-stdalign_check.o"]).
  OPT_LEVEL = Some(3)
  TARGET = Some(aarch64-unknown-linux-musl)
  HOST = Some(x86_64-unknown-linux-gnu)
  cargo:rerun-if-env-changed=CC_aarch64-unknown-linux-musl
  CC_aarch64-unknown-linux-musl = Some(/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-cc)
  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(false)
  cargo:rerun-if-env-changed=CFLAGS
  CFLAGS = None
  cargo:rerun-if-env-changed=TARGET_CFLAGS
  TARGET_CFLAGS = None
  cargo:rerun-if-env-changed=CFLAGS_aarch64_unknown_linux_musl
  CFLAGS_aarch64_unknown_linux_musl = None
  cargo:rerun-if-env-changed=CFLAGS_aarch64-unknown-linux-musl
  CFLAGS_aarch64-unknown-linux-musl = None
  CARGO_ENCODED_RUSTFLAGS = Some(-Clinker=/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-ld-L/nix/store/qjcach3bzi6390xs5gw3grivhmls6yn0-libcxx-static-aarch64-unknown-linux-musl-19.1.7/lib-lc++-lc++abi-luring-L/nix/store/21nnvj4vjci5y5ynwr9b09dlnfycz2kg-liburing-static-aarch64-unknown-linux-musl-2.9/lib-Clink-arg=-static-Ctarget-feature=+crt-static)
  cargo:warning=Compilation of 'builtin_swap_check.c' succeeded - Ok(["/tmp/nix-build-atlas-release-deps-0.3.4.drv-0/source/target/aarch64-unknown-linux-musl/release/build/aws-lc-sys-99f44b0176b6a8ac/out/out-builtin_swap_check/e89dd77a48967ab8-builtin_swap_check.o"]).
  OPT_LEVEL = Some(3)
  OUT_DIR = Some(/tmp/nix-build-atlas-release-deps-0.3.4.drv-0/source/target/aarch64-unknown-linux-musl/release/build/aws-lc-sys-99f44b0176b6a8ac/out)
  TARGET = Some(aarch64-unknown-linux-musl)
  HOST = Some(x86_64-unknown-linux-gnu)
  cargo:rerun-if-env-changed=CC_aarch64-unknown-linux-musl
  CC_aarch64-unknown-linux-musl = Some(/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-cc)
  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(false)
  cargo:rerun-if-env-changed=CFLAGS
  CFLAGS = None
  cargo:rerun-if-env-changed=TARGET_CFLAGS
  TARGET_CFLAGS = None
  cargo:rerun-if-env-changed=CFLAGS_aarch64_unknown_linux_musl
  CFLAGS_aarch64_unknown_linux_musl = None
  cargo:rerun-if-env-changed=CFLAGS_aarch64-unknown-linux-musl
  CFLAGS_aarch64-unknown-linux-musl = None
  CARGO_ENCODED_RUSTFLAGS = Some(-Clinker=/nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-ld-L/nix/store/qjcach3bzi6390xs5gw3grivhmls6yn0-libcxx-static-aarch64-unknown-linux-musl-19.1.7/lib-lc++-lc++abi-luring-L/nix/store/21nnvj4vjci5y5ynwr9b09dlnfycz2kg-liburing-static-aarch64-unknown-linux-musl-2.9/lib-Clink-arg=-static-Ctarget-feature=+crt-static)
  --- stderr
  thread 'main' panicked at /nix/store/2wslnnqjvrn68f6sx3l4cp6ad74wp3g2-vendor-cargo-deps/c19b7c6f923b580ac259164a89f2577984ad5ab09ee9d583b888f934adbbe8d0/aws-lc-sys-0.29.0/builder/cc_builder.rs:471:9:
  COMPILER: /nix/store/d2mrnjfhvcavv93ph07ydlikw3zz65mf-aarch64-unknown-linux-musl-clang-wrapper-19.1.7/bin/aarch64-unknown-linux-musl-ccARGS: ["-O3", "-ffunction-sections", "-fdata-sections", "-fPIC", "--target=aarch64-unknown-linux-musl", "-Wall", "-Wextra", "/nix/store/sm08wq5phnhfz524q8bcbn23rvlfjkvb-cargo-package-aws-lc-sys-0.29.0/aws-lc/tests/compiler_features_tests/memcmp_invalid_stripped_check.c", "-Wno-unused-parameter", "-o", "/tmp/nix-build-atlas-release-deps-0.3.4.drv-0/source/target/aarch64-unknown-linux-musl/release/build/aws-lc-sys-99f44b0176b6a8ac/out/memcmp_invalid_stripped_check"]EXECUTED: trueERROR: /nix/store/apflylnmi0dl9zl05qr26b6bgnxlr03k-aarch64-unknown-linux-musl-binutils-2.44/bin/aarch64-unknown-linux-musl-ld: skipping incompatible /nix/store/6hqzbvz50bm87hcj4qfn51gh7arxj8a6-gcc-14.2.1.20250322-libgcc/lib/libgcc_s.so.1 when searching for libgcc_s.so.1
  /nix/store/apflylnmi0dl9zl05qr26b6bgnxlr03k-aarch64-unknown-linux-musl-binutils-2.44/bin/aarch64-unknown-linux-musl-ld: skipping incompatible /nix/store/6hqzbvz50bm87hcj4qfn51gh7arxj8a6-gcc-14.2.1.20250322-libgcc/lib/libgcc_s.so.1 when searching for libgcc_s.so.1
  /nix/store/apflylnmi0dl9zl05qr26b6bgnxlr03k-aarch64-unknown-linux-musl-binutils-2.44/bin/aarch64-unknown-linux-musl-ld: cannot find libgcc_s.so.1: No such file or directory
  /nix/store/apflylnmi0dl9zl05qr26b6bgnxlr03k-aarch64-unknown-linux-musl-binutils-2.44/bin/aarch64-unknown-linux-musl-ld: skipping incompatible /nix/store/6hqzbvz50bm87hcj4qfn51gh7arxj8a6-gcc-14.2.1.20250322-libgcc/lib/libgcc_s.so.1 when searching for libgcc_s.so.1
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  OUTPUT: Failed to compile memcmp_invalid_stripped_check
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
warning: build failed, waiting for other jobs to finish...
error: builder for '/nix/store/lwgsf1yl6rx0p537vdkxvwr3bs8vk05b-atlas-release-deps-0.3.4.drv' failed with exit code 101
error: 1 dependencies of derivation '/nix/store/1ijwbv751rk1bd6kd47rmn86jpgbdk03-atlas-0.3.4.drv' failed to build
Error: Process completed with exit code 1.

[PierreBeucher]

Same error here. Not using Nix but Cross for cross compiling Linux => Mac. Supporting cross compilation seems an important feature as this library is included in lots of packages (like rustls which is used fairly often) and lots of projects rely on cross compilation to target MacOS / Darwin environments.

Thanks in advance !

[theoparis]

I would also like to see the long term solution of pkgconfig support in aws-lc-rs.