Use *last* path segment not first

sigp · Feb 1, 2024 · 30f768f · 30f768f
1 parent 52eba9f
commit 30f768f
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Showing 2 changed files with 18 additions and 11 deletions.
diff --git a/src/lib.rs b/src/lib.rs
@@ -240,14 +240,14 @@ pub fn superstruct(args: TokenStream, input: TokenStream) -> TokenStream {
                 let mut next_variant_field = output_field.clone();
                 match &mut next_variant_field.ty {
                     Type::Path(ref mut p) => {
-                        let first_segment = &mut p
+                        let last_segment = &mut p
                             .path
                             .segments
-                            .first_mut()
+                            .last_mut()
                             .expect("path should have at least one segment");
-                        let inner_ty_name = first_segment.ident.clone();
+                        let inner_ty_name = last_segment.ident.clone();
                         let next_variant_ty_name = format_ident!("{}{}", inner_ty_name, variant);
-                        first_segment.ident = next_variant_ty_name;
+                        last_segment.ident = next_variant_ty_name;
                     }
                     _ => panic!("field must be a path"),
                 };

diff --git a/tests/flatten.rs b/tests/flatten.rs
@@ -96,12 +96,19 @@ fn flatten_subset() {
 
 #[test]
 fn flatten_not_first_field() {
-    #[superstruct(variants(A, B), variant_attributes(derive(Debug, PartialEq, Eq)))]
-    #[derive(Debug, PartialEq, Eq)]
-    struct InnerMessageTwo {
-        pub x: u64,
-        #[superstruct(only(B))]
-        pub y: u64,
+    use test_mod::*;
+
+    // Put this type in a submodule to test path parsing in `flatten`.
+    pub mod test_mod {
+        use superstruct::superstruct;
+
+        #[superstruct(variants(A, B), variant_attributes(derive(Debug, PartialEq, Eq)))]
+        #[derive(Debug, PartialEq, Eq)]
+        pub struct InnerMessageTwo {
+            pub x: u64,
+            #[superstruct(only(B))]
+            pub y: u64,
+        }
     }
 
     #[superstruct(variants(A, B), variant_attributes(derive(Debug, PartialEq, Eq)))]
@@ -110,7 +117,7 @@ fn flatten_not_first_field() {
         #[superstruct(only(A), partial_getter(copy))]
         pub other: u64,
         #[superstruct(flatten)]
-        pub inner: InnerMessageTwo,
+        pub inner: test_mod::InnerMessageTwo,
     }
 
     let message_a = MessageTwo::A(MessageTwoA {