From 124a306cd7bad7f315a36e3abb4a205b6aa5188f Mon Sep 17 00:00:00 2001
From: Erick Tryzelaar <erick.tryzelaar@gmail.com>
Date: Fri, 6 Mar 2015 22:14:13 -0800
Subject: [PATCH] Fix #[derive_serialize] for generic structs

---
 serde2/serde2_macros/src/lib.rs | 51 ++++++++++++++++++++-------------
 serde2/tests/test_macros.rs     | 34 ++++++++++++++++++++++
 2 files changed, 65 insertions(+), 20 deletions(-)

diff --git a/serde2/serde2_macros/src/lib.rs b/serde2/serde2_macros/src/lib.rs
index 0dff7c9b..23e2ec33 100644
--- a/serde2/serde2_macros/src/lib.rs
+++ b/serde2/serde2_macros/src/lib.rs
@@ -158,7 +158,8 @@ fn serialize_substructure(cx: &ExtCtxt,
                                      visitor,
                                      substr.type_ident,
                                      &named_fields,
-                                     struct_def)
+                                     struct_def,
+                                     generics)
                 }
                 (false, false) => {
                     panic!("struct has named and unnamed fields")
@@ -269,16 +270,17 @@ fn serialize_tuple_struct(cx: &ExtCtxt,
     })
 }
 
-
 fn serialize_struct(cx: &ExtCtxt,
                     span: Span,
                     visitor: P<Expr>,
                     type_ident: Ident,
                     fields: &[(Ident, Span)],
-                    struct_def: &StructDef) -> P<Expr> {
-    let type_name = cx.expr_str(
-        span,
-        token::get_ident(type_ident));
+                    struct_def: &StructDef,
+                    generics: &ast::Generics) -> P<Expr> {
+    let ctx = builder::Ctx::new();
+    let builder = builder::AstBuilder::new(&ctx).span(span);
+
+    let type_name = builder.expr().str(type_ident);
     let len = fields.len();
 
     let aliases : Vec<Option<&ast::Lit>> = struct_def.fields.iter()
@@ -289,18 +291,11 @@ fn serialize_struct(cx: &ExtCtxt,
         .zip(aliases.iter())
         .enumerate()
         .map(|(i, (&(name, span), alias_lit))| {
-            let first = if i == 0 {
-                quote_expr!(cx, true)
-            } else {
-                quote_expr!(cx, false)
-            };
+            let first = builder.expr().bool(i == 0);
 
-            let expr = match alias_lit {
-                &Some(lit) => {
-                    let lit = (*lit).clone();
-                    cx.expr_lit(lit.span, lit.node)
-                },
-                &None => cx.expr_str(span, token::get_ident(name)),
+            let expr = match *alias_lit {
+                Some(lit) => builder.expr().build_lit(P(lit.clone())),
+                None => builder.expr().str(name),
             };
 
             let i = i as u32;
@@ -315,13 +310,29 @@ fn serialize_struct(cx: &ExtCtxt,
         })
         .collect();
 
+    let type_generics = builder.from_generics(generics.clone())
+        .strip_bounds()
+        .build();
+
+    let visitor_impl_generics = builder.from_generics(generics.clone())
+        .add_lifetime_bound("'__a")
+        .add_ty_param_bound(
+            builder.path().global().ids(&["serde2", "ser", "Serialize"]).build()
+        )
+        .lifetime_name("'__a")
+        .build();
+
+    let visitor_generics = builder.from_generics(visitor_impl_generics.clone())
+        .strip_bounds()
+        .build();
+
     quote_expr!(cx, {
-        struct Visitor<'a> {
+        struct Visitor $visitor_impl_generics {
             state: u32,
-            value: &'a $type_ident,
+            value: &'__a $type_ident $type_generics,
         }
 
-        impl<'a> ::serde2::ser::MapVisitor for Visitor<'a> {
+        impl $visitor_impl_generics ::serde2::ser::MapVisitor for Visitor $visitor_generics {
             #[inline]
             fn visit<V>(&mut self, visitor: &mut V) -> Result<Option<V::Value>, V::Error>
                 where V: ::serde2::ser::Visitor,
diff --git a/serde2/tests/test_macros.rs b/serde2/tests/test_macros.rs
index 5e86cbaa..18d67642 100644
--- a/serde2/tests/test_macros.rs
+++ b/serde2/tests/test_macros.rs
@@ -33,6 +33,14 @@ struct NamedUnit;
 #[derive_serialize]
 struct NamedTuple<'a, 'b, A: 'a, B: 'b, C>(&'a A, &'b mut B, C);
 
+#[derive(Debug, PartialEq)]
+#[derive_serialize]
+struct NamedMap<'a, 'b, A: 'a, B: 'b, C> {
+    a: &'a A,
+    b: &'b mut B,
+    c: C,
+}
+
 #[derive(Debug, PartialEq)]
 #[derive_serialize]
 //#[derive_deserialize]
@@ -97,6 +105,32 @@ fn test_named_tuple() {
     );
 }
 
+#[test]
+fn test_named_map() {
+    let a = 5;
+    let mut b = 6;
+    let c = 7;
+    let named_map = NamedMap {
+        a: &a,
+        b: &mut b,
+        c: c,
+    };
+
+    assert_eq!(
+        json::to_string(&named_map).unwrap(),
+        "{\"a\":5,\"b\":6,\"c\":7}"
+    );
+
+    assert_eq!(
+        json::to_value(&named_map),
+        Value::Object(btreemap![
+            "a".to_string() => Value::I64(5),
+            "b".to_string() => Value::I64(6),
+            "c".to_string() => Value::I64(7)
+        ])
+    );
+}
+
 #[test]
 fn test_enum_unit() {
     assert_eq!(