clang build fails with "invalid version 'softfloat'" on aarch64-unknown-none-softfloat target with cc crate 1.2.17

[jrm224]

When building a Rust project that uses the cc crate (version 1.2.17) for the aarch64-unknown-none-softfloat target, the build fails if clang is used as the C compiler.

The error message from clang is:

clang: error: version 'softfloat' in target triple 'aarch64-unknown-none-softfloat' is invalid

The cc crate appears to be invoking clang with the full target triple --target=aarch64-unknown-none-softfloat. It seems that some versions of clang do not accept the softfloat version string within the target triple for this architecture.

Steps to Reproduce (based on our experience):

Use a build.rs script that utilizes the cc crate (version 1.2.17).
Set the build target to aarch64-unknown-none-softfloat (either through environment variables like TARGET or by calling build.target() in the build script).
Ensure clang is selected as the C compiler (e.g., env::set_var("CC", "clang"); in build.rs or via environment variable).
Run cargo build --target aarch64-unknown-none-softfloat.

[NobodyXu]

It seems that some versions of clang do not accept the softfloat version string within the target triple for this architecture.

Is it installed from homebrew?

Previously we have encountered similar issues with homebrew clang

[madsmtm]

Huh? We should be passing --target=aarch64-unknown-none, that's what src/target/generated.rs is for:

cc-rs/src/target/generated.rs

Line 33 in d9dd20e

("aarch64-unknown-none-softfloat", "aarch64-unknown-none"),

I wonder why this isn't working?

[jrm224]

No, we don't have homebrew in our stack :/

[madsmtm]

I cannot reproduce this with cargo build --target aarch64-unknown-none-softfloat in a basic build.rs that builds an empty C file.

Could you post a minimal reproducer / post the contents of your build.rs? Are you setting any environment variables (like CFLAGS=--target=aarch64-unknown-none-softfloat)?

[qwandor]

This seems to be a regression, cc 1.2.16 works but 1.2.17 doesn't.

$ clang --version
Debian clang version 19.1.7 (1)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm-19/bin

[madsmtm]

Well, in that case it's definitely #1413. But I still cannot reproduce it, nor even fathom what the issue could be?

If you don't want to post a full reproducer, could I get you to check out this repository, run cargo build --target aarch64-unknown-none-softfloat -vv -p cc-test, and post the output?

[jrm224]

Oddly enough, I've also tried 1.0.79 and I'm getting the same error.

[jrm224]

Running the command you posted above (after fixing some errors) produces the following:

error[E0463]: can't find crate for std
|
= note: the aarch64-unknown-none-softfloat target may not support the standard library
= note: std is required by cc_test because it does not declare #![no_std]

For more information about this error, try rustc --explain E0463.
error: could not compile cc-test (lib) due to 1 previous error

This might (?) still be a problem with the setup, but I've had a look online and am not sure how to tackle this. Any ideas? Does this help?

[madsmtm]

Odd, that sounds like you're missing a rustup target add aarch64-unknown-none-softfloat?

[jrm224]

That's what I thought as well but I get the following:

[...]:~/rust/trusted-firmware-a/rust$ rustup target add aarch64-unknown-none-softfloat
info: component 'rust-std' for target 'aarch64-unknown-none-softfloat' is up to date

[madsmtm]

Ah, right, that's actually kinda expected, since aarch64-unknown-none-softfloat doesn't support std... My bad.

Could you test the following Cargo project:
https://gist.github.com/madsmtm/3c53305b58624ee8251a38b709db6412

With cargo build --target aarch64-unknown-none-softfloat -vv?

[jrm224]

Sure thing, here's the output:

[...]:~/rust/3c53305b58624ee8251a38b709db6412$ cargo build --target aarch64-unknown-none-softfloat -vv
Updating crates.io index
Locking 2 packages to latest compatible versions
Downloaded cc v1.2.17
Downloaded 1 crate (105.8 KB) in 0.18s
Compiling shlex v1.3.0
Running CARGO=/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo CARGO_CRATE_NAME=shlex CARGO_MANIFEST_DIR=/usr/local/google/home/jeremimiller/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/shlex-1.3.0 CARGO_MANIFEST_PATH=/usr/local/google/home/jeremimiller/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/shlex-1.3.0/Cargo.toml CARGO_PKG_AUTHORS='comex <[email protected]>:Fenhl <[email protected]>:Adrian Taylor <[email protected]>:Alex Touchet <[email protected]>:Daniel Parks <[email protected]>:Garrett Berg <[email protected]>' CARGO_PKG_DESCRIPTION='Split a string into shell words, like Python'\''s shlex.' CARGO_PKG_HOMEPAGE='' CARGO_PKG_LICENSE='MIT OR Apache-2.0' CARGO_PKG_LICENSE_FILE='' CARGO_PKG_NAME=shlex CARGO_PKG_README=README.md CARGO_PKG_REPOSITORY='https://github.com/comex/rust-shlex' CARGO_PKG_RUST_VERSION=1.46.0 CARGO_PKG_VERSION=1.3.0 CARGO_PKG_VERSION_MAJOR=1 CARGO_PKG_VERSION_MINOR=3 CARGO_PKG_VERSION_PATCH=0 CARGO_PKG_VERSION_PRE='' LD_LIBRARY_PATH='/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps:/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib' /usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc --crate-name shlex --edition=2015 /usr/local/google/home/jeremimiller/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/shlex-1.3.0/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=185 --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 --cfg 'feature="default"' --cfg 'feature="std"' --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values("default", "std"))' -C metadata=108dd8bee21f2f06 -C extra-filename=-da8f62f0b407b770 --out-dir /usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps -L dependency=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps --cap-lints warn
warning: unexpected cfg condition name: manual_codegen_check
--> /usr/local/google/home/jeremimiller/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/shlex-1.3.0/src/bytes.rs:353:12
|
353 | #[cfg_attr(manual_codegen_check, inline(never))]
| ^^^^^^^^^^^^^^^^^^^^
|
= help: expected names are: clippy, debug_assertions, doc, docsrs, doctest, feature, fmt_debug, miri, overflow_checks, panic, proc_macro, relocation_model, rustfmt, sanitize, sanitizer_cfi_generalize_pointers, sanitizer_cfi_normalize_integers, target_abi, target_arch, target_endian, target_env, target_family, target_feature, target_has_atomic, target_has_atomic_equal_alignment, target_has_atomic_load_store, target_os, target_pointer_width, target_thread_local, target_vendor, test, ub_checks, unix, and windows
= help: consider using a Cargo feature instead
= help: or consider adding in Cargo.toml the check-cfg lint config for the lint:
[lints.rust]
unexpected_cfgs = { level = "warn", check-cfg = ['cfg(manual_codegen_check)'] }
= help: or consider adding println!("cargo::rustc-check-cfg=cfg(manual_codegen_check)"); to the top of the build.rs
= note: see https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html for more information about checking conditional configuration
= note: #[warn(unexpected_cfgs)] on by default

Compiling cc v1.2.17
Running CARGO=/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo CARGO_CRATE_NAME=cc CARGO_MANIFEST_DIR=/usr/local/google/home/jeremimiller/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/cc-1.2.17 CARGO_MANIFEST_PATH=/usr/local/google/home/jeremimiller/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/cc-1.2.17/Cargo.toml CARGO_PKG_AUTHORS='Alex Crichton <[email protected]>' CARGO_PKG_DESCRIPTION='A build-time dependency for Cargo build scripts to assist in invoking the native C compiler to compile native C code into a static archive to be linked into Rust code. ' CARGO_PKG_HOMEPAGE='https://github.com/rust-lang/cc-rs' CARGO_PKG_LICENSE='MIT OR Apache-2.0' CARGO_PKG_LICENSE_FILE='' CARGO_PKG_NAME=cc CARGO_PKG_README=README.md CARGO_PKG_REPOSITORY='https://github.com/rust-lang/cc-rs' CARGO_PKG_RUST_VERSION=1.63 CARGO_PKG_VERSION=1.2.17 CARGO_PKG_VERSION_MAJOR=1 CARGO_PKG_VERSION_MINOR=2 CARGO_PKG_VERSION_PATCH=17 CARGO_PKG_VERSION_PRE='' LD_LIBRARY_PATH='/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps:/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib' /usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc --crate-name cc --edition=2018 /usr/local/google/home/jeremimiller/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/cc-1.2.17/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=185 --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values("jobserver", "parallel"))' -C metadata=52425963560081fd -C extra-filename=-2cd70bee92931dec --out-dir /usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps -L dependency=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps --extern shlex=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps/libshlex-da8f62f0b407b770.rmeta --cap-lints warn
warning: shlex (lib) generated 1 warning
Compiling example v0.1.0 (/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412)
Running CARGO=/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo CARGO_CRATE_NAME=build_script_build CARGO_MANIFEST_DIR=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412 CARGO_MANIFEST_PATH=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/Cargo.toml CARGO_PKG_AUTHORS='' CARGO_PKG_DESCRIPTION='' CARGO_PKG_HOMEPAGE='' CARGO_PKG_LICENSE='' CARGO_PKG_LICENSE_FILE='' CARGO_PKG_NAME=example CARGO_PKG_README='' CARGO_PKG_REPOSITORY='' CARGO_PKG_RUST_VERSION='' CARGO_PKG_VERSION=0.1.0 CARGO_PKG_VERSION_MAJOR=0 CARGO_PKG_VERSION_MINOR=1 CARGO_PKG_VERSION_PATCH=0 CARGO_PKG_VERSION_PRE='' CARGO_PRIMARY_PACKAGE=1 LD_LIBRARY_PATH='/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps:/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib' /usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc --crate-name build_script_build --edition=2021 build.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=185 --crate-type bin --emit=dep-info,link -C embed-bitcode=no -C debuginfo=2 --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values())' -C metadata=6d61f7bdabb6b384 -C extra-filename=-12890180ddec8c37 --out-dir /usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/build/example-12890180ddec8c37 -C incremental=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/incremental -L dependency=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps --extern cc=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps/libcc-2cd70bee92931dec.rlib
Running CARGO=/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo CARGO_CFG_FEATURE='' CARGO_CFG_PANIC=abort CARGO_CFG_TARGET_ABI=softfloat CARGO_CFG_TARGET_ARCH=aarch64 CARGO_CFG_TARGET_ENDIAN=little CARGO_CFG_TARGET_ENV='' CARGO_CFG_TARGET_HAS_ATOMIC=128,16,32,64,8,ptr CARGO_CFG_TARGET_OS=none CARGO_CFG_TARGET_POINTER_WIDTH=64 CARGO_CFG_TARGET_VENDOR=unknown CARGO_ENCODED_RUSTFLAGS='' CARGO_MANIFEST_DIR=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412 CARGO_MANIFEST_PATH=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/Cargo.toml CARGO_PKG_AUTHORS='' CARGO_PKG_DESCRIPTION='' CARGO_PKG_HOMEPAGE='' CARGO_PKG_LICENSE='' CARGO_PKG_LICENSE_FILE='' CARGO_PKG_NAME=example CARGO_PKG_README='' CARGO_PKG_REPOSITORY='' CARGO_PKG_RUST_VERSION='' CARGO_PKG_VERSION=0.1.0 CARGO_PKG_VERSION_MAJOR=0 CARGO_PKG_VERSION_MINOR=1 CARGO_PKG_VERSION_PATCH=0 CARGO_PKG_VERSION_PRE='' DEBUG=true HOST=x86_64-unknown-linux-gnu LD_LIBRARY_PATH='/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps:/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug:/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib:/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib' NUM_JOBS=128 OPT_LEVEL=0 OUT_DIR=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/aarch64-unknown-none-softfloat/debug/build/example-7ff52e202dd0314c/out PROFILE=debug RUSTC=/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc RUSTDOC=/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustdoc TARGET=aarch64-unknown-none-softfloat /usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/build/example-12890180ddec8c37/build-script-build
[example 0.1.0] cargo:rerun-if-changed=build.rs
[example 0.1.0] cargo:rerun-if-changed=foo.c
[example 0.1.0] OUT_DIR = Some(/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/aarch64-unknown-none-softfloat/debug/build/example-7ff52e202dd0314c/out)
[example 0.1.0] OPT_LEVEL = Some(0)
[example 0.1.0] TARGET = Some(aarch64-unknown-none-softfloat)
[example 0.1.0] HOST = Some(x86_64-unknown-linux-gnu)
[example 0.1.0] cargo:rerun-if-env-changed=CC_aarch64-unknown-none-softfloat
[example 0.1.0] CC_aarch64-unknown-none-softfloat = None
[example 0.1.0] cargo:rerun-if-env-changed=CC_aarch64_unknown_none_softfloat
[example 0.1.0] CC_aarch64_unknown_none_softfloat = None
[example 0.1.0] cargo:rerun-if-env-changed=TARGET_CC
[example 0.1.0] TARGET_CC = None
[example 0.1.0] cargo:rerun-if-env-changed=CC
[example 0.1.0] CC = None
[example 0.1.0] cargo:rerun-if-env-changed=CROSS_COMPILE
[example 0.1.0] CROSS_COMPILE = None
[example 0.1.0] RUSTC_LINKER = None
[example 0.1.0] cargo:rerun-if-env-changed=CC_ENABLE_DEBUG_OUTPUT
[example 0.1.0] RUSTC_WRAPPER = None
[example 0.1.0] cargo:rerun-if-env-changed=CRATE_CC_NO_DEFAULTS
[example 0.1.0] CRATE_CC_NO_DEFAULTS = None
[example 0.1.0] DEBUG = Some(true)
[example 0.1.0] CARGO_CFG_TARGET_FEATURE = None
[example 0.1.0] cargo:rerun-if-env-changed=CFLAGS
[example 0.1.0] CFLAGS = None
[example 0.1.0] cargo:rerun-if-env-changed=TARGET_CFLAGS
[example 0.1.0] TARGET_CFLAGS = None
[example 0.1.0] cargo:rerun-if-env-changed=CFLAGS_aarch64_unknown_none_softfloat
[example 0.1.0] CFLAGS_aarch64_unknown_none_softfloat = None
[example 0.1.0] cargo:rerun-if-env-changed=CFLAGS_aarch64-unknown-none-softfloat
[example 0.1.0] CFLAGS_aarch64-unknown-none-softfloat = None
[example 0.1.0] CARGO_ENCODED_RUSTFLAGS = Some()
[example 0.1.0] cargo:rerun-if-env-changed=AR_aarch64-unknown-none-softfloat
[example 0.1.0] AR_aarch64-unknown-none-softfloat = None
[example 0.1.0] cargo:rerun-if-env-changed=AR_aarch64_unknown_none_softfloat
[example 0.1.0] AR_aarch64_unknown_none_softfloat = None
[example 0.1.0] cargo:rerun-if-env-changed=TARGET_AR
[example 0.1.0] TARGET_AR = None
[example 0.1.0] cargo:rerun-if-env-changed=AR
[example 0.1.0] AR = None
[example 0.1.0] cargo:rerun-if-env-changed=ARFLAGS
[example 0.1.0] ARFLAGS = None
[example 0.1.0] cargo:rerun-if-env-changed=TARGET_ARFLAGS
[example 0.1.0] TARGET_ARFLAGS = None
[example 0.1.0] cargo:rerun-if-env-changed=ARFLAGS_aarch64_unknown_none_softfloat
[example 0.1.0] ARFLAGS_aarch64_unknown_none_softfloat = None
[example 0.1.0] cargo:rerun-if-env-changed=ARFLAGS_aarch64-unknown-none-softfloat
[example 0.1.0] ARFLAGS_aarch64-unknown-none-softfloat = None
[example 0.1.0] cargo:rustc-link-lib=static=foo
[example 0.1.0] cargo:rustc-link-search=native=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/aarch64-unknown-none-softfloat/debug/build/example-7ff52e202dd0314c/out
Running CARGO=/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo CARGO_CRATE_NAME=example CARGO_MANIFEST_DIR=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412 CARGO_MANIFEST_PATH=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/Cargo.toml CARGO_PKG_AUTHORS='' CARGO_PKG_DESCRIPTION='' CARGO_PKG_HOMEPAGE='' CARGO_PKG_LICENSE='' CARGO_PKG_LICENSE_FILE='' CARGO_PKG_NAME=example CARGO_PKG_README='' CARGO_PKG_REPOSITORY='' CARGO_PKG_RUST_VERSION='' CARGO_PKG_VERSION=0.1.0 CARGO_PKG_VERSION_MAJOR=0 CARGO_PKG_VERSION_MINOR=1 CARGO_PKG_VERSION_PATCH=0 CARGO_PKG_VERSION_PRE='' CARGO_PRIMARY_PACKAGE=1 LD_LIBRARY_PATH='/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps:/usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib' OUT_DIR=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/aarch64-unknown-none-softfloat/debug/build/example-7ff52e202dd0314c/out /usr/local/google/home/jeremimiller/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc --crate-name example --edition=2021 lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=185 --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values())' -C metadata=4d797fa7b06c6947 -C extra-filename=-b904edf080ab12bc --out-dir /usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/aarch64-unknown-none-softfloat/debug/deps --target aarch64-unknown-none-softfloat -C incremental=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/aarch64-unknown-none-softfloat/debug/incremental -L dependency=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/aarch64-unknown-none-softfloat/debug/deps -L dependency=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/debug/deps -L native=/usr/local/google/home/jeremimiller/rust/3c53305b58624ee8251a38b709db6412/target/aarch64-unknown-none-softfloat/debug/build/example-7ff52e202dd0314c/out -l static=foo
Finished dev profile [unoptimized + debuginfo] target(s) in 1.42s

[madsmtm]

Well, that works, so I'm feeling fairly confident the problem isn't with cc-rs. You're absolutely sure that it isn't your project itself, or some dependency, that passes --target?

[jrm224]

Ok, I'll dig a bit more next week, thanks for helping out. For now we've got the =1.2.16 version workaround. I'll post here when/if I confirm what the problem is.

[jrm224]

I can fairly confidently confirm this isn't an issue with cc-rs, I've just managed to compile with 1.2.17. The problem is likely something to do with interplay between older versions of the crates we use.