Add support for macro expansion inside trait items

src/libsyntax/ext/base.rs

@@ -227,6 +227,11 @@ pub trait MacResult {
         None
     }
 
+    /// Create zero or more trait items.
+    fn make_trait_items(self: Box<Self>) -> Option<SmallVector<ast::TraitItem>> {
+        None
+    }
+
     /// Create a pattern.
     fn make_pat(self: Box<Self>) -> Option<P<ast::Pat>> {
         None
@@ -274,6 +279,7 @@ make_MacEager! {
     pat: P<ast::Pat>,
     items: SmallVector<P<ast::Item>>,
     impl_items: SmallVector<ast::ImplItem>,
+    trait_items: SmallVector<ast::TraitItem>,
     stmts: SmallVector<ast::Stmt>,
     ty: P<ast::Ty>,
 }
@@ -291,6 +297,10 @@ impl MacResult for MacEager {
         self.impl_items
     }
 
+    fn make_trait_items(self: Box<Self>) -> Option<SmallVector<ast::TraitItem>> {
+        self.trait_items
+    }
+
     fn make_stmts(self: Box<Self>) -> Option<SmallVector<ast::Stmt>> {
         match self.stmts.as_ref().map_or(0, |s| s.len()) {
             0 => make_stmts_default!(self),
@@ -399,6 +409,14 @@ impl MacResult for DummyResult {
         }
     }
 
+    fn make_trait_items(self: Box<DummyResult>) -> Option<SmallVector<ast::TraitItem>> {
+        if self.expr_only {
+            None
+        } else {
+            Some(SmallVector::zero())
+        }
+    }
+
     fn make_stmts(self: Box<DummyResult>) -> Option<SmallVector<ast::Stmt>> {
         Some(SmallVector::one(
             codemap::respan(self.span,