Place compile-fail expected errors on their own line

test_suite/tests/compile-fail/duplicate-attribute/rename-and-ser.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: 12:10: 12:19: unknown serde field attribute `serialize`
+#[derive(Serialize)]
 struct S {
     #[serde(rename="x", serialize="y")]
+    //~^^^ ERROR: unknown serde field attribute `serialize`
     x: (),
 }
 

test_suite/tests/compile-fail/duplicate-attribute/rename-rename-de.rs

@@ -9,10 +9,11 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: 12:10: 12:19: duplicate serde attribute `rename`
+#[derive(Serialize)]
 struct S {
     #[serde(rename="x")]
     #[serde(rename(deserialize="y"))]
+    //~^^^^ ERROR: duplicate serde attribute `rename`
     x: (),
 }
 

test_suite/tests/compile-fail/duplicate-attribute/rename-ser-rename-ser.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: 12:10: 12:19: duplicate serde attribute `rename`
+#[derive(Serialize)]
 struct S {
     #[serde(rename(serialize="x"), rename(serialize="y"))]
+    //~^^^ ERROR: duplicate serde attribute `rename`
     x: (),
 }
 

test_suite/tests/compile-fail/duplicate-attribute/rename-ser-rename.rs

@@ -9,10 +9,11 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: 12:10: 12:19: duplicate serde attribute `rename`
+#[derive(Serialize)]
 struct S {
     #[serde(rename(serialize="x"))]
     #[serde(rename="y")]
+    //~^^^^ ERROR: duplicate serde attribute `rename`
     x: (),
 }
 

test_suite/tests/compile-fail/duplicate-attribute/rename-ser-ser.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: 12:10: 12:19: duplicate serde attribute `rename`
+#[derive(Serialize)]
 struct S {
     #[serde(rename(serialize="x", serialize="y"))]
+    //~^^^ ERROR: duplicate serde attribute `rename`
     x: (),
 }
 

test_suite/tests/compile-fail/duplicate-attribute/two-rename-ser.rs

@@ -9,10 +9,11 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: 12:10: 12:19: duplicate serde attribute `rename`
+#[derive(Serialize)]
 struct S {
     #[serde(rename(serialize="x"))]
     #[serde(rename(serialize="y"))]
+    //~^^^^ ERROR: duplicate serde attribute `rename`
     x: (),
 }
 

test_suite/tests/compile-fail/duplicate-attribute/with-and-serialize-with.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: 12:10: 12:19: duplicate serde attribute `serialize_with`
+#[derive(Serialize)]
 struct S {
     #[serde(with = "w", serialize_with = "s")]
+    //~^^^ ERROR: duplicate serde attribute `serialize_with`
     x: (),
 }