auto merge of #6223 : alexcrichton/rust/issue-6183, r=pcwalton

Closes #6183.

The first commit changes the compiler's method of treating a `for` loop, and all the remaining commits are just dealing with the fallout.

The biggest fallout was the `IterBytes` trait, although it's really a whole lot nicer now because all of the `iter_bytes_XX` methods are just and-ed together. Sadly there was a huge amount of stuff that's `cfg(stage0)` gated, but whoever lands the next snapshot is going to have a lot of fun deleting all this code!

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) => {
@@ -78,7 +76,7 @@ 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;
         }
@@ -86,8 +84,14 @@ fn iter_bytes_substructure(cx: @ext_ctxt, span: span, substr: &Substructure) ->
     }
 
     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)
+    }
 }

src/libsyntax/ext/expand.rs

@@ -195,18 +195,8 @@ pub fn expand_item(extsbox: @mut SyntaxEnv,
 }
 
 // does this attribute list contain "macro_escape" ?
-pub fn contains_macro_escape (attrs: &[ast::attribute]) -> bool{
-    let mut accum = false;
-    do attrs.each |attr| {
-        let mname = attr::get_attr_name(attr);
-        if (mname == @~"macro_escape") {
-            accum = true;
-            false
-        } else {
-            true
-        }
-    }
-    accum
+pub fn contains_macro_escape (attrs: &[ast::attribute]) -> bool {
+    attrs.any(|attr| "macro_escape" == *attr::get_attr_name(attr))
 }
 
 // this macro disables (one layer of) macro

src/libsyntax/ext/pipes/proto.rs

@@ -100,6 +100,7 @@ pub impl state_ {
 
     /// Iterate over the states that can be reached in one message
     /// from this state.
+    #[cfg(stage0)]
     fn reachable(&self, f: &fn(state) -> bool) {
         for self.messages.each |m| {
             match *m {
@@ -111,6 +112,21 @@ pub impl state_ {
             }
         }
     }
+    /// Iterate over the states that can be reached in one message
+    /// from this state.
+    #[cfg(not(stage0))]
+    fn reachable(&self, f: &fn(state) -> bool) -> bool {
+        for self.messages.each |m| {
+            match *m {
+              message(_, _, _, _, Some(next_state { state: ref id, _ })) => {
+                let state = self.proto.get_state((*id));
+                if !f(state) { return false; }
+              }
+              _ => ()
+            }
+        }
+        return true;
+    }
 }
 
 pub type protocol = @mut protocol_;