rust: kernel: remove fmt!, fix clippy::uninlined-format-args

Rather than export a macro that delegates to `core::format_args`, simply
re-export `core::format_args` as `fmt` from the prelude. This exposes
clippy warnings which were previously obscured by this macro, such as:

    warning: variables can be used directly in the `format!` string
      --> ../drivers/cpufreq/rcpufreq_dt.rs:21:43
       |
    21 |     let prop_name = CString::try_from_fmt(fmt!("{}-supply", name)).ok()?;
       |                                           ^^^^^^^^^^^^^^^^^^^^^^^
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
       = note: `-W clippy::uninlined-format-args` implied by `-W clippy::all`
       = help: to override `-W clippy::all` add `#[allow(clippy::uninlined_format_args)]`
    help: change this to
       |
    21 -     let prop_name = CString::try_from_fmt(fmt!("{}-supply", name)).ok()?;
    21 +     let prop_name = CString::try_from_fmt(fmt!("{name}-supply")).ok()?;
       |

Thus fix them in the same commit. This could possibly be fixed in two
stages, but the diff is small enough (outside of kernel/str.rs) that I
hope it can be taken in a single commit.

Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250704-core-cstr-prepare-v1-1-a91524037783@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: tamird

drivers/cpufreq/rcpufreq_dt.rs

@@ -9,7 +9,6 @@ use kernel::{
     cpumask::CpumaskVar,
     device::{Core, Device},
     error::code::*,
-    fmt,
     macros::vtable,
     module_platform_driver, of, opp, platform,
     prelude::*,
@@ -19,7 +18,7 @@ use kernel::{
 
 /// Finds exact supply name from the OF node.
 fn find_supply_name_exact(dev: &Device, name: &str) -> Option<CString> {
-    let prop_name = CString::try_from_fmt(fmt!("{}-supply", name)).ok()?;
+    let prop_name = CString::try_from_fmt(fmt!("{name}-supply")).ok()?;
     dev.property_present(&prop_name)
         .then(|| CString::try_from_fmt(fmt!("{name}")).ok())
         .flatten()

drivers/gpu/nova-core/firmware.rs

@@ -24,11 +24,12 @@ pub(crate) struct Firmware {
 
 impl Firmware {
     pub(crate) fn new(dev: &device::Device, chipset: Chipset, ver: &str) -> Result<Firmware> {
-        let mut chip_name = CString::try_from_fmt(fmt!("{}", chipset))?;
+        let mut chip_name = CString::try_from_fmt(fmt!("{chipset}"))?;
         chip_name.make_ascii_lowercase();
+        let chip_name = &*chip_name;
 
         let request = |name_| {
-            CString::try_from_fmt(fmt!("nvidia/{}/gsp/{}-{}.bin", &*chip_name, name_, ver))
+            CString::try_from_fmt(fmt!("nvidia/{chip_name}/gsp/{name_}-{ver}.bin"))
                 .and_then(|path| firmware::Firmware::request(&path, dev))
         };
 

rust/kernel/opp.rs

@@ -345,7 +345,7 @@ impl Drop for ConfigToken {
 /// impl ConfigOps for Driver {}
 ///
 /// fn configure(dev: &ARef<Device>) -> Result<ConfigToken> {
-///     let name = CString::try_from_fmt(fmt!("{}", "slow"))?;
+///     let name = CString::try_from_fmt(fmt!("slow"))?;
 ///
 ///     // The OPP configuration is cleared once the [`ConfigToken`] goes out of scope.
 ///     Config::<Driver>::new()

rust/kernel/prelude.rs

@@ -31,9 +31,9 @@ pub use super::{build_assert, build_error};
 // `super::std_vendor` is hidden, which makes the macro inline for some reason.
 #[doc(no_inline)]
 pub use super::dbg;
-pub use super::fmt;
 pub use super::{dev_alert, dev_crit, dev_dbg, dev_emerg, dev_err, dev_info, dev_notice, dev_warn};
 pub use super::{pr_alert, pr_crit, pr_debug, pr_emerg, pr_err, pr_info, pr_notice, pr_warn};
+pub use core::format_args as fmt;
 
 pub use super::{try_init, try_pin_init};
 

rust/kernel/str.rs

@@ -54,13 +54,13 @@ impl fmt::Display for BStr {
     /// Formats printable ASCII characters, escaping the rest.
     ///
     /// ```
-    /// # use kernel::{fmt, b_str, str::{BStr, CString}};
+    /// # use kernel::{prelude::fmt, b_str, str::{BStr, CString}};
     /// let ascii = b_str!("Hello, BStr!");
-    /// let s = CString::try_from_fmt(fmt!("{}", ascii))?;
+    /// let s = CString::try_from_fmt(fmt!("{ascii}"))?;
     /// assert_eq!(s.as_bytes(), "Hello, BStr!".as_bytes());
     ///
     /// let non_ascii = b_str!("🦀");
-    /// let s = CString::try_from_fmt(fmt!("{}", non_ascii))?;
+    /// let s = CString::try_from_fmt(fmt!("{non_ascii}"))?;
     /// assert_eq!(s.as_bytes(), "\\xf0\\x9f\\xa6\\x80".as_bytes());
     /// # Ok::<(), kernel::error::Error>(())
     /// ```
@@ -85,14 +85,14 @@ impl fmt::Debug for BStr {
     /// escaping the rest.
     ///
     /// ```
-    /// # use kernel::{fmt, b_str, str::{BStr, CString}};
+    /// # use kernel::{prelude::fmt, b_str, str::{BStr, CString}};
     /// // Embedded double quotes are escaped.
     /// let ascii = b_str!("Hello, \"BStr\"!");
-    /// let s = CString::try_from_fmt(fmt!("{:?}", ascii))?;
+    /// let s = CString::try_from_fmt(fmt!("{ascii:?}"))?;
     /// assert_eq!(s.as_bytes(), "\"Hello, \\\"BStr\\\"!\"".as_bytes());
     ///
     /// let non_ascii = b_str!("😺");
-    /// let s = CString::try_from_fmt(fmt!("{:?}", non_ascii))?;
+    /// let s = CString::try_from_fmt(fmt!("{non_ascii:?}"))?;
     /// assert_eq!(s.as_bytes(), "\"\\xf0\\x9f\\x98\\xba\"".as_bytes());
     /// # Ok::<(), kernel::error::Error>(())
     /// ```
@@ -429,15 +429,15 @@ impl fmt::Display for CStr {
     ///
     /// ```
     /// # use kernel::c_str;
-    /// # use kernel::fmt;
+    /// # use kernel::prelude::fmt;
     /// # use kernel::str::CStr;
     /// # use kernel::str::CString;
     /// let penguin = c_str!("🐧");
-    /// let s = CString::try_from_fmt(fmt!("{}", penguin))?;
+    /// let s = CString::try_from_fmt(fmt!("{penguin}"))?;
     /// assert_eq!(s.as_bytes_with_nul(), "\\xf0\\x9f\\x90\\xa7\0".as_bytes());
     ///
     /// let ascii = c_str!("so \"cool\"");
-    /// let s = CString::try_from_fmt(fmt!("{}", ascii))?;
+    /// let s = CString::try_from_fmt(fmt!("{ascii}"))?;
     /// assert_eq!(s.as_bytes_with_nul(), "so \"cool\"\0".as_bytes());
     /// # Ok::<(), kernel::error::Error>(())
     /// ```
@@ -459,16 +459,16 @@ impl fmt::Debug for CStr {
     ///
     /// ```
     /// # use kernel::c_str;
-    /// # use kernel::fmt;
+    /// # use kernel::prelude::fmt;
     /// # use kernel::str::CStr;
     /// # use kernel::str::CString;
     /// let penguin = c_str!("🐧");
-    /// let s = CString::try_from_fmt(fmt!("{:?}", penguin))?;
+    /// let s = CString::try_from_fmt(fmt!("{penguin:?}"))?;
     /// assert_eq!(s.as_bytes_with_nul(), "\"\\xf0\\x9f\\x90\\xa7\"\0".as_bytes());
     ///
     /// // Embedded double quotes are escaped.
     /// let ascii = c_str!("so \"cool\"");
-    /// let s = CString::try_from_fmt(fmt!("{:?}", ascii))?;
+    /// let s = CString::try_from_fmt(fmt!("{ascii:?}"))?;
     /// assert_eq!(s.as_bytes_with_nul(), "\"so \\\"cool\\\"\"\0".as_bytes());
     /// # Ok::<(), kernel::error::Error>(())
     /// ```
@@ -578,7 +578,7 @@ mod tests {
 
     macro_rules! format {
         ($($f:tt)*) => ({
-            CString::try_from_fmt(::kernel::fmt!($($f)*))?.to_str()?
+            CString::try_from_fmt(fmt!($($f)*))?.to_str()?
         })
     }
 
@@ -840,7 +840,7 @@ impl fmt::Write for Formatter {
 /// # Examples
 ///
 /// ```
-/// use kernel::{str::CString, fmt};
+/// use kernel::{str::CString, prelude::fmt};
 ///
 /// let s = CString::try_from_fmt(fmt!("{}{}{}", "abc", 10, 20))?;
 /// assert_eq!(s.as_bytes_with_nul(), "abc1020\0".as_bytes());
@@ -930,9 +930,3 @@ impl fmt::Debug for CString {
         fmt::Debug::fmt(&**self, f)
     }
 }
-
-/// A convenience alias for [`core::format_args`].
-#[macro_export]
-macro_rules! fmt {
-    ($($f:tt)*) => ( ::core::format_args!($($f)*) )
-}