From 30a449e04a32033d8e4844fdb4938a0ebccfa37b Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Fri, 7 Aug 2026 20:24:27 +0900 Subject: [PATCH] rust: bug: fix warn_on macro build error on UML 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; Call the method through its fully qualified path, which resolves without any import at the expansion site. Cc: stable@vger.kernel.org Fixes: dff64b072708 ("rust: Add warn_on macro") Signed-off-by: FUJITA Tomonori Link: https://patch.msgid.link/20260807112427.1039056-1-tomo@flapping.org Signed-off-by: Miguel Ojeda --- 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 309131b1e9d0..3566f0234ca4 100644 --- a/rust/kernel/bug.rs +++ b/rust/kernel/bug.rs @@ -91,7 +91,7 @@ macro_rules! warn_flags { // with a valid null-terminated string. unsafe { $crate::bindings::warn_slowpath_fmt( - $crate::c_str!(::core::file!()).as_char_ptr(), + $crate::str::CStrExt::as_char_ptr($crate::c_str!(::core::file!())), line!() as $crate::ffi::c_int, $flags as $crate::ffi::c_uint, ::core::ptr::null(),