Get syn building on 1.15.0 again by changing the Fields::iter implementation
diff --git a/src/lib.rs b/src/lib.rs
index 77b0d23..380552c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -287,8 +287,8 @@
#[cfg(any(feature = "full", feature = "derive"))]
mod data;
#[cfg(any(feature = "full", feature = "derive"))]
-pub use data::{Field, Fields, FieldsNamed, FieldsUnnamed, Variant, VisCrate, VisPublic,
- VisRestricted, Visibility};
+pub use data::{Field, Fields, FieldsNamed, FieldsUnnamed, FieldsIter, Variant,
+ VisCrate, VisPublic, VisRestricted, Visibility};
#[cfg(any(feature = "full", feature = "derive"))]
mod expr;