Implement ToTokens without reliance on {:?}

Author: dtolnay

impl/src/attr.rs

@@ -230,7 +230,18 @@ impl ToTokens for Display<'_> {
 
 impl ToTokens for Trait {
     fn to_tokens(&self, tokens: &mut TokenStream) {
-        let trait_name = format_ident!("{}", format!("{:?}", self));
-        tokens.extend(quote!(::core::fmt::#trait_name));
+        let trait_name = match self {
+            Trait::Debug => "Debug",
+            Trait::Display => "Display",
+            Trait::Octal => "Octal",
+            Trait::LowerHex => "LowerHex",
+            Trait::UpperHex => "UpperHex",
+            Trait::Pointer => "Pointer",
+            Trait::Binary => "Binary",
+            Trait::LowerExp => "LowerExp",
+            Trait::UpperExp => "UpperExp",
+        };
+        let ident = Ident::new(trait_name, Span::call_site());
+        tokens.extend(quote!(::core::fmt::#ident));
     }
 }