Fix position of auto in auto trait declaration

src/items.rs

@@ -963,9 +963,9 @@ pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent)
         let mut result = String::with_capacity(128);
         let header = format!(
             "{}{}{}trait ",
-            format_auto(is_auto),
             format_visibility(&item.vis),
             format_unsafety(unsafety),
+            format_auto(is_auto),
         );
         result.push_str(&header);
 

tests/source/trait.rs

@@ -95,3 +95,5 @@ trait FooBar = Foo
 
 // #2637
 auto trait Example {}
+pub auto trait PubExample {}
+pub unsafe auto trait PubUnsafeExample {}

tests/target/trait.rs

@@ -133,3 +133,5 @@ trait FooBar = Foo
 
 // #2637
 auto trait Example {}
+pub auto trait PubExample {}
+pub unsafe auto trait PubUnsafeExample {}