Generate more concise code for pass-through format

Fixes #13.
dtolnay · Oct 11, 2019 · 5994705 · 5994705
1 parent a6b1d28
commit 5994705
Showing 1 changed file with 15 additions and 3 deletions.
diff --git a/impl/src/attr.rs b/impl/src/attr.rs
@@ -77,9 +77,21 @@ impl ToTokens for Display {
     fn to_tokens(&self, tokens: &mut TokenStream) {
         let fmt = &self.fmt;
         let args = &self.args;
-        tokens.extend(quote! {
-            write!(formatter, #fmt #args)
-        });
+        if self.was_shorthand && fmt.value() == "{}" {
+            let arg = args.clone().into_iter().skip(1).next().unwrap();
+            tokens.extend(quote! {
+                std::fmt::Display::fmt(#arg, formatter)
+            });
+        } else if self.was_shorthand && fmt.value() == "{:?}" {
+            let arg = args.clone().into_iter().skip(1).next().unwrap();
+            tokens.extend(quote! {
+                std::fmt::Debug::fmt(#arg, formatter)
+            });
+        } else {
+            tokens.extend(quote! {
+                write!(formatter, #fmt #args)
+            });
+        }
     }
 }