Reduce coupling to implementation details of the formatting machinery by
avoiding direct use for `core`'s formatting traits and macros.

Signed-off-by: Tamir Duberstein <tamird@gmail.com>
---
 rust/kernel/device/property.rs | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/rust/kernel/device/property.rs b/rust/kernel/device/property.rs
index 49ee12a906db..3a332a8c53a9 100644
--- a/rust/kernel/device/property.rs
+++ b/rust/kernel/device/property.rs
@@ -11,6 +11,7 @@
     alloc::KVec,
     bindings,
     error::{to_result, Result},
+    fmt,
     prelude::*,
     str::{CStr, CString},
     types::{ARef, Opaque},
@@ -68,16 +69,16 @@ pub fn is_of_node(&self) -> bool {
         unsafe { bindings::is_of_node(self.as_raw()) }
     }
 
-    /// Returns an object that implements [`Display`](core::fmt::Display) for
+    /// Returns an object that implements [`Display`](fmt::Display) for
     /// printing the name of a node.
     ///
     /// This is an alternative to the default `Display` implementation, which
     /// prints the full path.
-    pub fn display_name(&self) -> impl core::fmt::Display + '_ {
+    pub fn display_name(&self) -> impl fmt::Display + '_ {
         struct FwNodeDisplayName<'a>(&'a FwNode);
 
-        impl core::fmt::Display for FwNodeDisplayName<'_> {
-            fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        impl fmt::Display for FwNodeDisplayName<'_> {
+            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                 // SAFETY: `self` is valid by its type invariant.
                 let name = unsafe { bindings::fwnode_get_name(self.0.as_raw()) };
                 if name.is_null() {
@@ -87,7 +88,7 @@ fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
                 // - `fwnode_get_name` returns null or a valid C string.
                 // - `name` was checked to be non-null.
                 let name = unsafe { CStr::from_char_ptr(name) };
-                write!(f, "{name}")
+                fmt::Display::fmt(name, f)
             }
         }
 
@@ -351,8 +352,8 @@ pub fn is_empty(&self) -> bool {
     }
 }
 
-impl core::fmt::Debug for FwNodeReferenceArgs {
-    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+impl fmt::Debug for FwNodeReferenceArgs {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{:?}", self.as_slice())
     }
 }
@@ -377,8 +378,8 @@ enum Node<'a> {
     Owned(ARef<FwNode>),
 }
 
-impl core::fmt::Display for FwNode {
-    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+impl fmt::Display for FwNode {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // The logic here is the same as the one in lib/vsprintf.c
         // (fwnode_full_name_string).
 
@@ -413,9 +414,9 @@ fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
                 // SAFETY: `fwnode_get_name_prefix` returns null or a
                 // valid C string.
                 let prefix = unsafe { CStr::from_char_ptr(prefix) };
-                write!(f, "{prefix}")?;
+                fmt::Display::fmt(prefix, f)?;
             }
-            write!(f, "{}", fwnode.display_name())?;
+            fmt::Display::fmt(&fwnode.display_name(), f)?;
         }
 
         Ok(())

-- 
2.50.1

On Wed Aug 13, 2025 at 5:39 PM CEST, Tamir Duberstein wrote:
> Reduce coupling to implementation details of the formatting machinery by
> avoiding direct use for `core`'s formatting traits and macros.
>
> Signed-off-by: Tamir Duberstein <tamird@gmail.com>

Reviewed-by: Benno Lossin <lossin@kernel.org>

> ---
>  rust/kernel/device/property.rs | 23 ++++++++++++-----------
>  1 file changed, 12 insertions(+), 11 deletions(-)
    
> @@ -413,9 +414,9 @@ fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
>                  // SAFETY: `fwnode_get_name_prefix` returns null or a
>                  // valid C string.
>                  let prefix = unsafe { CStr::from_char_ptr(prefix) };
> -                write!(f, "{prefix}")?;
> +                fmt::Display::fmt(prefix, f)?;
>              }
> -            write!(f, "{}", fwnode.display_name())?;

So we're not able to use `write!` with our `Display` or did you also
write a `FmtAdapter` wrapper for that? (don't think we need it now, just
wanted to know if we have this issue possibly in the future)

---
Cheers,
Benno

> +            fmt::Display::fmt(&fwnode.display_name(), f)?;
>          }
>  
>          Ok(())

On Thu, Aug 14, 2025 at 4:54 PM Benno Lossin <lossin@kernel.org> wrote:
>
> On Wed Aug 13, 2025 at 5:39 PM CEST, Tamir Duberstein wrote:
> > Reduce coupling to implementation details of the formatting machinery by
> > avoiding direct use for `core`'s formatting traits and macros.
> >
> > Signed-off-by: Tamir Duberstein <tamird@gmail.com>
>
> Reviewed-by: Benno Lossin <lossin@kernel.org>
>
> > ---
> >  rust/kernel/device/property.rs | 23 ++++++++++++-----------
> >  1 file changed, 12 insertions(+), 11 deletions(-)
>
> > @@ -413,9 +414,9 @@ fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
> >                  // SAFETY: `fwnode_get_name_prefix` returns null or a
> >                  // valid C string.
> >                  let prefix = unsafe { CStr::from_char_ptr(prefix) };
> > -                write!(f, "{prefix}")?;
> > +                fmt::Display::fmt(prefix, f)?;
> >              }
> > -            write!(f, "{}", fwnode.display_name())?;
>
> So we're not able to use `write!` with our `Display` or did you also
> write a `FmtAdapter` wrapper for that? (don't think we need it now, just
> wanted to know if we have this issue possibly in the future)

Correct; we cannot use `write!` with our `Display`.

Apologies for the late reply - I had sent this back in August but was
still being throttled by gmail :(