[PATCH] rust: rust_is_available: warn for `bindgen` < 0.72.1 && libclang >= 22
From: Miguel Ojeda <ojeda@kernel.org>
Date: 2026-07-19 12:05:41
Also in:
linux-kbuild
Subsystem:
rust, the rest · Maintainers:
Miguel Ojeda, Linus Torvalds
Starting with LLVM 22, `clang_getTypeDeclaration()` may return a forward
declaration instead of the type definition. This made `bindgen` generate
opaque types [1][2], which in turn made us fail with e.g.
error[E0609]: no field `__bindgen_anon_1` on type `bindings::kernel_param`
--> rust/kernel/module_param.rs:78:46
|
78 | let container = unsafe { &*((*param).__bindgen_anon_1.arg.cast::<SetOnce<T>>()) };
| ^^^^^^^^^^^^^^^^ unknown field
|
= note: available field is: `_address`
This was fixed in `bindgen` 0.72.1 [3].
In order to clarify what is going on and avoid confusion [4][5], add
a warning to `rust_is_available.sh` about it when the versions match,
similar to past warnings like the one removed in:
commit ae64324ad5c1 ("rust: rust_is_available: remove warning for `bindgen` < 0.69.5 && libclang >= 19.1")
In addition, even if the versions match, check if the issue appears to
not reproduce with the given binaries, to avoid a warning in such a case.
Finally, include tests.
Link: https://github.com/rust-lang/rust-bindgen/issues/3264 [1]
Link: https://github.com/Rust-for-Linux/linux/issues/353 [2] # "Missing fields in nested class with LLVM 22."
Link: https://github.com/rust-lang/rust-bindgen/pull/3278 [3]
Reported-by: Burak Emir <redacted>
Link: https://github.com/Rust-for-Linux/linux/issues/1247 [4]
Link: https://lore.kernel.org/rust-for-linux/CABwQupNfMAJOGqRM9ke6tj4f53dCCsBDKU7Vp+zf8mwk7bqt8Q@mail.gmail.com/ (local) [5]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
While it was known, I added Reported-by anyway -- please let me know if
you prefer otherwise.
Would you mind confirming you get the warning?
Thanks!
scripts/rust_is_available.sh | 14 +++++++++
.../rust_is_available_bindgen_libclang_22.h | 5 ++++
scripts/rust_is_available_test.py | 30 ++++++++++++++++++-
3 files changed, 48 insertions(+), 1 deletion(-)
create mode 100644 scripts/rust_is_available_bindgen_libclang_22.h
diff --git a/scripts/rust_is_available.sh b/scripts/rust_is_available.sh
index 551f1ebd0dcb..c30983562a2f 100755
--- a/scripts/rust_is_available.sh
+++ b/scripts/rust_is_available.sh@@ -208,6 +208,20 @@ if [ "$bindgen_libclang_cversion" -lt "$bindgen_libclang_min_cversion" ]; then exit 1 fi +if [ "$bindgen_libclang_cversion" -ge 2200000 ] && + [ "$rust_bindings_generator_cversion" -lt 7201 ]; then + # Distributions may have patched the issue. + if ! "$BINDGEN" $(dirname $0)/rust_is_available_bindgen_libclang_22.h | grep -q 'pub foo'; then + echo >&2 "***" + echo >&2 "*** Rust bindings generator '$BINDGEN' < 0.72.1 together with libclang >= 22" + echo >&2 "*** may not work due to a bug (https://github.com/rust-lang/rust-bindgen/pull/3278)." + echo >&2 "*** Your bindgen version: $rust_bindings_generator_version" + echo >&2 "*** Your libclang version: $bindgen_libclang_version" + echo >&2 "***" + warning=1 + fi +fi + # If the C compiler is Clang, then we can also check whether its version # matches the `libclang` version used by the Rust bindings generator. #
diff --git a/scripts/rust_is_available_bindgen_libclang_22.h b/scripts/rust_is_available_bindgen_libclang_22.h
new file mode 100644
index 000000000000..6b33544c14a8
--- /dev/null
+++ b/scripts/rust_is_available_bindgen_libclang_22.h@@ -0,0 +1,5 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +struct S; +struct S { + int foo; +};
diff --git a/scripts/rust_is_available_test.py b/scripts/rust_is_available_test.py
index d6d54b7ea42a..e14cf2c5695e 100755
--- a/scripts/rust_is_available_test.py
+++ b/scripts/rust_is_available_test.py@@ -54,16 +54,23 @@ else: """) @classmethod - def generate_bindgen(cls, version_stdout, libclang_stderr): + def generate_bindgen(cls, version_stdout, libclang_stderr, libclang_22_patched=False): if libclang_stderr is None: libclang_case = f"raise SystemExit({cls.bindgen_default_bindgen_libclang_failure_exit_code})" else: libclang_case = f"print({repr(libclang_stderr)}, file=sys.stderr)" + if libclang_22_patched: + libclang_22_case = "print('pub foo: ::std::os::raw::c_int,')" + else: + libclang_22_case = "pass" + return cls.generate_executable(f"""#!/usr/bin/env python3 import sys if "rust_is_available_bindgen_libclang.h" in " ".join(sys.argv): {libclang_case} +elif "rust_is_available_bindgen_libclang_22.h" in " ".join(sys.argv): + {libclang_22_case} else: print({repr(version_stdout)}) """)
@@ -248,6 +255,27 @@ else: result = self.run_script(self.Expected.FAILURE, { "BINDGEN": bindgen }) self.assertIn(f"libclang (used by the Rust bindings generator '{bindgen}') is too old.", result.stderr) + def test_bindgen_bad_libclang_22(self): + for (bindgen_version, libclang_version, expected_not_patched) in ( + ("0.71.1", "21.1.0", self.Expected.SUCCESS), + ("0.71.1", "22.0.0", self.Expected.SUCCESS_WITH_WARNINGS), + ("0.71.1", "22.1.0", self.Expected.SUCCESS_WITH_WARNINGS), + + ("0.72.0", "22.0.0", self.Expected.SUCCESS_WITH_WARNINGS), + + ("0.72.1", "22.0.0", self.Expected.SUCCESS), + ): + with self.subTest(bindgen_version=bindgen_version, libclang_version=libclang_version): + cc = self.generate_clang(f"clang version {libclang_version}") + libclang_stderr = f"scripts/rust_is_available_bindgen_libclang.h:2:9: warning: clang version {libclang_version} [-W#pragma-messages], err: false" + bindgen = self.generate_bindgen(f"bindgen {bindgen_version}", libclang_stderr) + result = self.run_script(expected_not_patched, { "BINDGEN": bindgen, "CC": cc }) + if expected_not_patched == self.Expected.SUCCESS_WITH_WARNINGS: + self.assertIn(f"Rust bindings generator '{bindgen}' < 0.72.1 together with libclang >= 22", result.stderr) + + bindgen = self.generate_bindgen(f"bindgen {bindgen_version}", libclang_stderr, libclang_22_patched=True) + result = self.run_script(self.Expected.SUCCESS, { "BINDGEN": bindgen, "CC": cc }) + def test_clang_matches_bindgen_libclang_different_bindgen(self): bindgen = self.generate_bindgen_libclang("scripts/rust_is_available_bindgen_libclang.h:2:9: warning: clang version 999.0.0 [-W#pragma-messages], err: false") result = self.run_script(self.Expected.SUCCESS_WITH_WARNINGS, { "BINDGEN": bindgen })
base-commit: 880c43b185ca52239e75bc546cc4f4d9154d0fed -- 2.55.0