tamer: xir::tree::attr: Display impls

tamer/src/xir/tree/attr.rs

@@ -25,6 +25,7 @@
 
 use super::QName;
 use crate::{span::Span, sym::SymbolId};
+use std::fmt::Display;
 
 /// An attribute.
 ///
@@ -143,6 +144,15 @@ impl Attr {
     }
 }
 
+impl Display for Attr {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Simple(attr) => attr.fmt(f),
+            Self::Extensible(parts) => parts.fmt(f),
+        }
+    }
+}
+
 /// Element attribute with an atomic value.
 ///
 /// This should be used in place of [`AttrParts`] whenever the attribute is
@@ -164,6 +174,12 @@ impl SimpleAttr {
     }
 }
 
+impl Display for SimpleAttr {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "`@{}=\"{}\"` at {}", self.name, self.value, self.span.0)
+    }
+}
+
 /// Element attribute with a value composed of multiple fragments.
 ///
 /// This should be used when one or more of these properties is desirable:
@@ -253,6 +269,12 @@ impl From<Attr> for AttrParts {
     }
 }
 
+impl Display for AttrParts {
+    fn fmt(&self, _f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        todo!("<AttrParts as std::fmt::Display>::fmt")
+    }
+}
+
 /// List of attributes.
 ///
 /// Attributes are ordered in XIR so that this IR will be suitable for code