Merge pull request diesel-rs#1467 from diesel-rs/sg-empty-infer-schema

Compile successfully when `infer_schema!` is used with an empty database

Author: weiznich

CHANGELOG.md

@@ -26,6 +26,11 @@ for Rust libraries in [RFC #1105](https://github.com/rust-lang/rfcs/blob/master/
 * Deprecated specifying a column name as `#[column_name(foo)]`. `#[column_name =
   "foo"]` should be used instead.
 
+### Fixed
+
+* `infer_schema!` generates valid code when run against a database with no
+  tables.
+
 ## [1.0.0] - 2018-01-02
 
 ### Added

diesel/src/macros/mod.rs

@@ -1079,6 +1079,8 @@ macro_rules! allow_tables_to_appear_in_same_query {
     };
 
     ($last_table:ident,) => {};
+
+    () => {};
 }
 
 #[macro_export]

diesel_tests/tests/schema.rs

@@ -11,6 +11,11 @@ infer_schema!("dotenv:MYSQL_DATABASE_URL");
 #[cfg(not(feature = "backend_specific_database_url"))]
 infer_schema!("dotenv:DATABASE_URL");
 
+#[cfg(feature = "sqlite")]
+mod test_infer_schema_works_on_empty_database {
+    infer_schema!(":memory:");
+}
+
 #[derive(PartialEq, Eq, Debug, Clone, Queryable, Identifiable, Insertable, AsChangeset,
          Associations, QueryableByName)]
 #[table_name = "users"]