From 28d67f4172268c8e9b6a291d8338afda41163249 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sat, 24 Dec 2016 13:10:06 -0500
Subject: [PATCH] Format variant-skip message only if variant is skipped

---
 serde_codegen/src/ser.rs | 34 ++++++++++++----------------------
 1 file changed, 12 insertions(+), 22 deletions(-)

diff --git a/serde_codegen/src/ser.rs b/serde_codegen/src/ser.rs
index e9eb38f4..65459abc 100644
--- a/serde_codegen/src/ser.rs
+++ b/serde_codegen/src/ser.rs
@@ -256,29 +256,19 @@ fn serialize_variant(
     let variant_ident = variant.ident.clone();
     let variant_name = variant.attrs.name().serialize_name();
 
-    let skipped_msg = format!("The enum variant {}::{} cannot be serialized",
-                              type_ident, variant_ident);
-    let skipped_err = quote! {
-        Err(_serde::ser::Error::invalid_value(#skipped_msg))
-    };
-
     if variant.attrs.skip_serializing() {
-        match variant.style {
-            Style::Unit => {
-                quote! {
-                    #type_ident::#variant_ident => #skipped_err,
-                }
-            },
-            Style::Newtype | Style::Tuple => {
-                quote! {
-                    #type_ident::#variant_ident(..) => #skipped_err,
-                }
-            },
-            Style::Struct => {
-                quote! {
-                    #type_ident::#variant_ident{..} => #skipped_err,
-                }
-            }
+        let skipped_msg = format!("The enum variant {}::{} cannot be serialized",
+                                type_ident, variant_ident);
+        let skipped_err = quote! {
+            Err(_serde::ser::Error::invalid_value(#skipped_msg))
+        };
+        let fields_pat = match variant.style {
+            Style::Unit => quote!(),
+            Style::Newtype | Style::Tuple => quote!( (..) ),
+            Style::Struct => quote!( {..} ),
+        };
+        quote! {
+            #type_ident::#variant_ident #fields_pat => #skipped_err,
         }
     } else { // variant wasn't skipped
         match variant.style {