---

yaml
---
r: 140681
b: refs/heads/try2
c: cdc266e
h: refs/heads/master
i:
  140679: 0ecb0b6
v: v3

Author: alexcrichton

[refs]

@@ -5,7 +5,7 @@ refs/heads/snap-stage3: 78a7676898d9f80ab540c6df5d4c9ce35bb50463
 refs/heads/try: 519addf6277dbafccbb4159db4b710c37eaa2ec5
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b
-refs/heads/try2: b01a40d45930f97e83753150dc1b39b26b3b398f
+refs/heads/try2: cdc266e47d8ee63a1eaf29c775f2cbc5f3a61bb4
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596
 refs/tags/release-0.3: b5f0d0f648d9a6153664837026ba1be43d3e2503

branches/try2/src/libsyntax/ext/deriving/iter_bytes.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use ast::{meta_item, item, expr};
+use ast::{meta_item, item, expr, and};
 use codemap::span;
 use ext::base::ext_ctxt;
 use ext::build;
@@ -31,7 +31,7 @@ pub fn expand_deriving_iter_bytes(cx: @ext_ctxt,
                     Literal(Path::new(~[~"bool"])),
                     Literal(Path::new(~[~"core", ~"to_bytes", ~"Cb"]))
                 ],
-                ret_ty: nil_ty(),
+                ret_ty: Literal(Path::new(~[~"bool"])),
                 const_nonmatching: false,
                 combine_substructure: iter_bytes_substructure
             }
@@ -58,13 +58,11 @@ fn iter_bytes_substructure(cx: @ext_ctxt, span: span, substr: &Substructure) ->
     };
     let iter_bytes_ident = substr.method_ident;
     let call_iterbytes = |thing_expr| {
-        build::mk_stmt(
-            cx, span,
-            build::mk_method_call(cx, span,
-                                  thing_expr, iter_bytes_ident,
-                                  copy lsb0_f))
+        build::mk_method_call(cx, span,
+                              thing_expr, iter_bytes_ident,
+                              copy lsb0_f)
     };
-    let mut stmts = ~[];
+    let mut exprs = ~[];
     let fields;
     match *substr.fields {
         Struct(ref fs) => {
@@ -78,16 +76,22 @@ fn iter_bytes_substructure(cx: @ext_ctxt, span: span, substr: &Substructure) ->
                 None => build::mk_uint(cx, span, index)
             };
 
-            stmts.push(call_iterbytes(discriminant));
+            exprs.push(call_iterbytes(discriminant));
 
             fields = fs;
         }
         _ => cx.span_bug(span, "Impossible substructure in `deriving(IterBytes)`")
     }
 
     for fields.each |&(_, field, _)| {
-        stmts.push(call_iterbytes(field));
+        exprs.push(call_iterbytes(field));
     }
 
-    build::mk_block(cx, span, ~[], stmts, None)
+    if exprs.len() == 0 {
+        cx.span_bug(span, "#[deriving(IterBytes)] needs at least one field");
+    }
+
+    do vec::foldl(exprs[0], exprs.slice(1, exprs.len())) |prev, me| {
+        build::mk_binary(cx, span, and, prev, *me)
+    }
 }