From: FUJITA Tomonori <tomo@flapping.org>
To: ojeda@kernel.org, richard@nod.at,
anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net
Cc: a.hindborg@kernel.org, acourbot@nvidia.com, aliceryhl@google.com,
bjorn3_gh@protonmail.com, boqun@kernel.org, dakr@kernel.org,
daniel.almeida@collabora.com, gary@garyguo.net,
lossin@kernel.org, tamird@kernel.org, tmgross@umich.edu,
work@onurozkan.dev, rust-for-linux@vger.kernel.org,
linux-um@lists.infradead.org,
FUJITA Tomonori <fujita.tomonori@gmail.com>
Subject: [PATCH v1] rust: bug: fix warn_on macro build error on UML
Date: Sat, 1 Aug 2026 11:25:01 +0900 [thread overview]
Message-ID: <20260801022501.722493-1-tomo@flapping.org> (raw)
From: FUJITA Tomonori <fujita.tomonori@gmail.com>
Callers that go through `kernel::prelude` have `CStrExt` in scope, but
code inside the `kernel` crate imports explicitly and may not. Using
`warn_on!` from such a module fails to build on UML, which is the only
configuration where `warn_flags!` needs a C string pointer rather than an
inline asm bug entry:
error[E0599]: no method named `as_char_ptr` found for reference `&ffi::CStr` in the current scope
--> linux/rust/kernel/bug.rs:83:49
|
83 | $crate::c_str!(::core::file!()).as_char_ptr(),
| ^^^^^^^^^^^
|
::: linux/rust/kernel/time.rs:427:9
|
427 | warn_on!(self.nanos < 0);
| ------------------------ in this macro invocation
|
= help: items from traits can only be used if the trait is in scope
= note: this error originates in the macro `$crate::warn_flags` which comes from the expansion of the macro `warn_on` (in Nightly builds, run with -Z mac)
help: trait `CStrExt` which provides `as_char_ptr` is implemented but not in scope; perhaps you want to import it
--> linux/rust/kernel/time.rs:27:1
|
27 + use crate::str::CStrExt;
Use the free function `as_char_ptr_in_const_context()` instead, as other exported macros already do.
Fixes: dff64b072708 ("rust: Add warn_on macro")
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
---
rust/kernel/bug.rs | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/rust/kernel/bug.rs b/rust/kernel/bug.rs
index ed943960f851..ca1ab69c977b 100644
--- a/rust/kernel/bug.rs
+++ b/rust/kernel/bug.rs
@@ -80,7 +80,7 @@ macro_rules! warn_flags {
// with a valid null-terminated string.
unsafe {
$crate::bindings::warn_slowpath_fmt(
- $crate::c_str!(::core::file!()).as_char_ptr(),
+ $crate::str::as_char_ptr_in_const_context($crate::c_str!(::core::file!())),
line!() as $crate::ffi::c_int,
$flags as $crate::ffi::c_uint,
::core::ptr::null(),
base-commit: 11028ab62899e4191e074ee364c712b77823a9c4
--
2.43.0
reply other threads:[~2026-08-01 2:25 UTC|newest]
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