Merge pull request diesel-rs#1744 from diesel-rs/sg-fix-sql-function

Don't add extra `[]` to attributes on no-return sql functions

Author: sgrif

diesel/src/expression/functions/mod.rs

@@ -548,7 +548,7 @@ macro_rules! __diesel_sqlite_register_fn {
 /// ```
 macro_rules! sql_function {
     ($(#$meta:tt)* fn $fn_name:ident $args:tt $(;)*) => {
-        sql_function!($(#[$meta])* fn $fn_name $args -> ());
+        sql_function!($(#$meta)* fn $fn_name $args -> ());
     };
 
     ($(#$meta:tt)* fn $fn_name:ident $args:tt -> $return_type:ty $(;)*) => {