Error::write_fmt()

Author: dwrensha

capnp/src/lib.rs

@@ -400,9 +400,13 @@ pub enum ErrorKind {
 }
 
 impl Error {
-    #[cfg(feature = "alloc")]
-    pub fn extra(&mut self, message: String) {
-        self.extra = message;
+    /// Writes to the `extra` field. Does nothing if the "alloc" feature is not enabled.
+    pub fn write_fmt(&mut self, fmt: core::fmt::Arguments<'_>) {
+        #[cfg(feature = "alloc")]
+        {
+            use core::fmt::Write;
+            let _ = self.extra.write_fmt(fmt);
+        }
     }
 
     #[cfg(feature = "alloc")]

capnp/src/schema.rs

@@ -1,8 +1,5 @@
 //! Convenience wrappers of the datatypes defined in schema.capnp.
 
-#[cfg(feature = "alloc")]
-use alloc::string::ToString;
-
 use crate::dynamic_value;
 use crate::introspect::{self, RawBrandedStructSchema, RawEnumSchema};
 use crate::private::layout;
@@ -76,8 +73,7 @@ impl StructSchema {
             // error needs to be mutable only when the alloc feature is enabled
             #[allow(unused_mut)]
             let mut error = crate::Error::from_kind(crate::ErrorKind::FieldNotFound);
-            #[cfg(feature = "alloc")]
-            error.extra(name.to_string());
+            write!(error, "{}", name);
             Err(error)
         }
     }