librustc: Disallow multiple patterns from appearing in a "let" declaration.

You can still initialize multiple variables at once with "let (x, y) = (1, 2)".

doc/rust.md

@@ -2325,7 +2325,9 @@ An example of a for loop over the contents of a vector:
 ~~~~
 # type foo = int;
 # fn bar(f: foo) { }
-# let a = 0, b = 0, c = 0;
+# let a = 0;
+# let b = 0;
+# let c = 0;
 
 let v: &[foo] = &[a, b, c];
 
@@ -3000,7 +3002,7 @@ allocated within the stack's memory. The value is a part of the stack frame.
 
 Local variables are immutable unless declared with `let mut`.  The
 `mut` keyword applies to all local variables declared within that
-declaration (so `let mut x, y` declares two mutable variables, `x` and
+declaration (so `let mut (x, y) = ...` declares two mutable variables, `x` and
 `y`).
 
 Function parameters are immutable unless declared with `mut`. The

doc/tutorial-ffi.md

@@ -159,8 +159,8 @@ pub struct Unique<T> {
     priv ptr: *mut T
 }
 
-pub impl<T: Owned> Unique<T> {
+impl<T: Owned> Unique<T> {
-    fn new(value: T) -> Unique<T> {
+    pub fn new(value: T) -> Unique<T> {
         unsafe {
             let ptr = malloc(std::sys::size_of::<T>() as size_t) as *mut T;
             assert!(!ptr::is_null(ptr));
@@ -171,12 +171,12 @@ pub impl<T: Owned> Unique<T> {
     }
 
     // the 'r lifetime results in the same semantics as `&*x` with ~T
-    fn borrow<'r>(&'r self) -> &'r T {
+    pub fn borrow<'r>(&'r self) -> &'r T {
         unsafe { cast::copy_lifetime(self, &*self.ptr) }
     }
 
     // the 'r lifetime results in the same semantics as `&mut *x` with ~T
-    fn borrow_mut<'r>(&'r mut self) -> &'r mut T {
+    pub fn borrow_mut<'r>(&'r mut self) -> &'r mut T {
         unsafe { cast::copy_mut_lifetime(self, &mut *self.ptr) }
     }
 }

doc/tutorial-macros.md

@@ -13,7 +13,8 @@ doing nothing otherwise:
 ~~~~
 # enum t { special_a(uint), special_b(uint) };
 # fn f() -> uint {
-# let input_1 = special_a(0), input_2 = special_a(0);
+# let input_1 = special_a(0);
+# let input_2 = special_a(0);
 match input_1 {
     special_a(x) => { return x; }
     _ => {}
@@ -38,7 +39,8 @@ the pattern in the above code:
 ~~~~
 # enum t { special_a(uint), special_b(uint) };
 # fn f() -> uint {
-# let input_1 = special_a(0), input_2 = special_a(0);
+# let input_1 = special_a(0);
+# let input_2 = special_a(0);
 macro_rules! early_return(
     ($inp:expr $sp:ident) => ( // invoke it like `(input_5 special_e)`
         match $inp {
@@ -155,7 +157,8 @@ instead of `*` to mean "at least one".
 ~~~~
 # enum t { special_a(uint),special_b(uint),special_c(uint),special_d(uint)};
 # fn f() -> uint {
-# let input_1 = special_a(0), input_2 = special_a(0);
+# let input_1 = special_a(0);
+# let input_2 = special_a(0);
 macro_rules! early_return(
     ($inp:expr, [ $($sp:ident)|+ ]) => (
         match $inp {

src/libextra/arena.rs

@@ -134,7 +134,7 @@ unsafe fn destroy_chunk(chunk: &Chunk) {
     while idx < fill {
         let tydesc_data: *uint = transmute(ptr::offset(buf, idx));
         let (tydesc, is_done) = un_bitpack_tydesc_ptr(*tydesc_data);
-        let size = (*tydesc).size, align = (*tydesc).align;
+        let (size, align) = ((*tydesc).size, (*tydesc).align);
 
         let after_tydesc = idx + sys::size_of::<*TypeDesc>();
 

src/libextra/fileinput.rs

@@ -194,8 +194,8 @@ impl FileInput {
     arguments. `"-"` represents `stdin`.
     */
     pub fn from_args() -> FileInput {
-        let args = os::args(),
+        let args = os::args();
-            pathed = pathify(args.tail(), true);
+        let pathed = pathify(args.tail(), true);
         FileInput::from_vec(pathed)
     }
 
@@ -222,8 +222,8 @@ impl FileInput {
             return false;
         }
 
-        let path_option = self.fi.files.shift(),
+        let path_option = self.fi.files.shift();
-            file = match path_option {
+        let file = match path_option {
             None => io::stdin(),
             Some(ref path) => io::file_reader(path).get()
         };
@@ -431,8 +431,8 @@ mod test {
     #[test]
     fn test_pathify() {
         let strs = [~"some/path",
-                    ~"some/other/path"],
+                    ~"some/other/path"];
-            paths = ~[Some(Path("some/path")),
+        let paths = ~[Some(Path("some/path")),
                       Some(Path("some/other/path"))];
 
         assert_eq!(pathify(strs, true), copy paths);
@@ -561,8 +561,10 @@ mod test {
 
     #[test]
     fn test_no_trailing_newline() {
-        let f1 = Some(Path("tmp/lib-fileinput-test-no-trailing-newline-1.tmp")),
+        let f1 =
-            f2 = Some(Path("tmp/lib-fileinput-test-no-trailing-newline-2.tmp"));
+            Some(Path("tmp/lib-fileinput-test-no-trailing-newline-1.tmp"));
+        let f2 =
+            Some(Path("tmp/lib-fileinput-test-no-trailing-newline-2.tmp"));
 
         let wr = io::file_writer(f1.get_ref(), [io::Create, io::Truncate]).get();
         wr.write_str("1\n2");

src/libextra/md4.rs

@@ -58,9 +58,9 @@ pub fn md4(msg: &[u8]) -> Quad {
     let e = msg.len();
     let mut x = vec::from_elem(16u, 0u32);
     while i < e {
-        let aa = a, bb = b, cc = c, dd = d;
+        let (aa, bb, cc, dd) = (a, b, c, d);
 
-        let mut j = 0u, base = i;
+        let mut (j, base) = (0u, i);
         while j < 16u {
             x[j] = (msg[base] as u32) + (msg[base + 1u] as u32 << 8u32) +
                 (msg[base + 2u] as u32 << 16u32) +

src/libextra/net_url.rs

@@ -416,7 +416,7 @@ fn get_authority(rawurl: &str) ->
     let mut port = None;
 
     let mut colon_count = 0;
-    let mut pos = 0, begin = 2, end = len;
+    let mut (pos, begin, end) = (0, 2, len);
 
     for str::each_chari(rawurl) |i,c| {
         if i < 2 { loop; } // ignore the leading //

src/libextra/num/bigint.rs

@@ -125,7 +125,7 @@ impl Ord for BigUint {
 impl TotalOrd for BigUint {
 
     fn cmp(&self, other: &BigUint) -> Ordering {
-        let s_len = self.data.len(), o_len = other.data.len();
+        let (s_len, o_len) = (self.data.len(), other.data.len());
         if s_len < o_len { return Less; }
         if s_len > o_len { return Greater;  }
 
@@ -255,7 +255,7 @@ impl Mul<BigUint, BigUint> for BigUint {
     fn mul(&self, other: &BigUint) -> BigUint {
         if self.is_zero() || other.is_zero() { return Zero::zero(); }
 
-        let s_len = self.data.len(), o_len = other.data.len();
+        let (s_len, o_len) = (self.data.len(), other.data.len());
         if s_len == 1 { return mul_digit(other, self.data[0]);  }
         if o_len == 1 { return mul_digit(self,  other.data[0]); }
 
@@ -447,7 +447,7 @@ impl Integer for BigUint {
 
     fn gcd(&self, other: &BigUint) -> BigUint {
         // Use Euclid's algorithm
-        let mut m = copy *self, n = copy *other;
+        let mut (m, n) = (copy *self, copy *other);
         while !m.is_zero() {
             let temp = m;
             m = n % temp;
@@ -1002,8 +1002,8 @@ impl Integer for BigInt {
     fn div_mod_floor(&self, other: &BigInt) -> (BigInt, BigInt) {
         // m.sign == other.sign
         let (d_ui, m_ui) = self.data.div_rem(&other.data);
-        let d = BigInt::from_biguint(Plus, d_ui),
+        let d = BigInt::from_biguint(Plus, d_ui);
-            m = BigInt::from_biguint(Plus, m_ui);
+        let m = BigInt::from_biguint(Plus, m_ui);
         match (self.sign, other.sign) {
             (_,    Zero)   => fail!(),
             (Plus, Plus)  | (Zero, Plus)  => (d, m),

src/libextra/terminfo/parser/compiled.rs

@@ -160,7 +160,9 @@ pub static stringnames: &'static[&'static str] = &'static[ "cbt", "_", "cr", "cs
 
 /// Parse a compiled terminfo entry, using long capability names if `longnames` is true
 pub fn parse(file: @Reader, longnames: bool) -> Result<~TermInfo, ~str> {
-    let bnames, snames, nnames;
+    let bnames;
+    let snames;
+    let nnames;
 
     if longnames {
         bnames = boolfnames;

src/librustc/front/config.rs

@@ -140,9 +140,18 @@ fn fold_block(
         b.stmts.filter_mapped(|a| filter_stmt(cx, *a));
     let filtered_view_items =
         b.view_items.filter_mapped(|a| filter_view_item(cx, *a));
+    let filtered_view_items =
+        filtered_view_items.map(|x| fld.fold_view_item(*x));
+    let mut resulting_stmts = ~[];
+    for filtered_stmts.each |stmt| {
+        match fld.fold_stmt(*stmt) {
+            None => {}
+            Some(stmt) => resulting_stmts.push(stmt),
+        }
+    }
     ast::blk_ {
-        view_items: vec::map(filtered_view_items, |x| fld.fold_view_item(*x)),
+        view_items: filtered_view_items,
-        stmts: vec::map(filtered_stmts, |x| fld.fold_stmt(*x)),
+        stmts: resulting_stmts,
         expr: b.expr.map(|x| fld.fold_expr(*x)),
         id: b.id,
         rules: b.rules,

src/librustc/middle/check_match.rs

@@ -380,7 +380,8 @@ pub fn missing_ctor(cx: @MatchCheckCtxt,
       }
       ty::ty_nil => None,
       ty::ty_bool => {
-        let mut true_found = false, false_found = false;
+        let mut true_found = false;
+        let mut false_found = false;
         for m.each |r| {
             match pat_ctor_id(cx, r[0]) {
               None => (),
@@ -513,10 +514,12 @@ pub fn specialize(cx: @MatchCheckCtxt,
                                 }
                             },
                             range(ref c_lo, ref c_hi) => {
-                                let m1 = compare_const_vals(c_lo, &e_v),
+                                let m1 = compare_const_vals(c_lo, &e_v);
-                                    m2 = compare_const_vals(c_hi, &e_v);
+                                let m2 = compare_const_vals(c_hi, &e_v);
                                 match (m1, m2) {
-                                    (Some(val1), Some(val2)) => (val1 >= 0 && val2 <= 0),
+                                    (Some(val1), Some(val2)) => {
+                                        (val1 >= 0 && val2 <= 0)
+                                    }
                                     _ => {
                                         cx.tcx.sess.span_err(pat_span,
                                             "mismatched types between ranges");
@@ -560,8 +563,8 @@ pub fn specialize(cx: @MatchCheckCtxt,
                                     }
                                 },
                             range(ref c_lo, ref c_hi) => {
-                                let m1 = compare_const_vals(c_lo, &e_v),
+                                let m1 = compare_const_vals(c_lo, &e_v);
-                                    m2 = compare_const_vals(c_hi, &e_v);
+                                let m2 = compare_const_vals(c_hi, &e_v);
                                 match (m1, m2) {
                                     (Some(val1), Some(val2)) => (val1 >= 0 && val2 <= 0),
                                     _ => {
@@ -622,7 +625,8 @@ pub fn specialize(cx: @MatchCheckCtxt,
                     }
                     _ => {
                         // Grab the class data that we care about.
-                        let class_fields, class_id;
+                        let class_fields;
+                        let class_id;
                         match ty::get(left_ty).sty {
                             ty::ty_struct(cid, _) => {
                                 class_id = cid;
@@ -667,8 +671,8 @@ pub fn specialize(cx: @MatchCheckCtxt,
                         }
                     },
                     range(ref c_lo, ref c_hi) => {
-                        let m1 = compare_const_vals(c_lo, &e_v),
+                        let m1 = compare_const_vals(c_lo, &e_v);
-                            m2 = compare_const_vals(c_hi, &e_v);
+                        let m2 = compare_const_vals(c_hi, &e_v);
                         match (m1, m2) {
                             (Some(val1), Some(val2)) => (val1 >= 0 && val2 <= 0),
                             _ => {
@@ -691,11 +695,11 @@ pub fn specialize(cx: @MatchCheckCtxt,
                     single => return Some(vec::to_owned(r.tail())),
                     _ => fail!("type error")
                 };
-                let v_lo = eval_const_expr(cx.tcx, lo),
+                let v_lo = eval_const_expr(cx.tcx, lo);
-                    v_hi = eval_const_expr(cx.tcx, hi);
+                let v_hi = eval_const_expr(cx.tcx, hi);
 
-                let m1 = compare_const_vals(&c_lo, &v_lo),
+                let m1 = compare_const_vals(&c_lo, &v_lo);
-                    m2 = compare_const_vals(&c_hi, &v_hi);
+                let m2 = compare_const_vals(&c_hi, &v_hi);
                 match (m1, m2) {
                     (Some(val1), Some(val2)) if val1 >= 0 && val2 <= 0 => {
                         Some(vec::to_owned(r.tail()))

src/librustc/middle/dataflow.rs

@@ -372,12 +372,10 @@ impl<'self, O:DataFlowOperator> PropagationContext<'self, O> {
                  in_out: &mut [uint],
                  loop_scopes: &mut ~[LoopScope]) {
         match decl.node {
-            ast::decl_local(ref locals) => {
+            ast::decl_local(local) => {
-                for locals.each |local| {
                 self.walk_pat(local.node.pat, in_out, loop_scopes);
                 self.walk_opt_expr(local.node.init, in_out, loop_scopes);
             }
-            }
 
             ast::decl_item(_) => {}
         }

src/librustc/middle/liveness.rs

@@ -948,14 +948,10 @@ impl Liveness {
     pub fn propagate_through_decl(&self, decl: @decl, succ: LiveNode)
                                   -> LiveNode {
         match decl.node {
-          decl_local(ref locals) => {
+            decl_local(ref local) => {
-            do locals.foldr(succ) |local, succ| {
                 self.propagate_through_local(*local, succ)
             }
-          }
+            decl_item(_) => succ,
-          decl_item(_) => {
-            succ
-          }
         }
     }
 

src/librustc/middle/region.rs

@@ -325,7 +325,9 @@ pub fn parent_id(cx: Context, span: span) -> ast::node_id {
 }
 
 /// Records the current parent (if any) as the parent of `child_id`.
-pub fn parent_to_expr(cx: Context, child_id: ast::node_id) {
+pub fn parent_to_expr(cx: Context, child_id: ast::node_id, sp: span) {
+    debug!("region::parent_to_expr(span=%?)",
+           cx.sess.codemap.span_to_str(sp));
     for cx.parent.each |parent_id| {
         cx.region_maps.record_parent(child_id, *parent_id);
     }
@@ -333,7 +335,7 @@ pub fn parent_to_expr(cx: Context, child_id: ast::node_id) {
 
 pub fn resolve_block(blk: &ast::blk, cx: Context, visitor: visit::vt<Context>) {
     // Record the parent of this block.
-    parent_to_expr(cx, blk.node.id);
+    parent_to_expr(cx, blk.node.id, blk.span);
 
     // Descend.
     let new_cx = Context {var_parent: Some(blk.node.id),
@@ -348,7 +350,7 @@ pub fn resolve_arm(arm: &ast::arm, cx: Context, visitor: visit::vt<Context>) {
 
 pub fn resolve_pat(pat: @ast::pat, cx: Context, visitor: visit::vt<Context>) {
     assert_eq!(cx.var_parent, cx.parent);
-    parent_to_expr(cx, pat.id);
+    parent_to_expr(cx, pat.id, pat.span);
     visit::visit_pat(pat, cx, visitor);
 }
 
@@ -359,7 +361,7 @@ pub fn resolve_stmt(stmt: @ast::stmt, cx: Context, visitor: visit::vt<Context>)
         }
         ast::stmt_expr(_, stmt_id) |
         ast::stmt_semi(_, stmt_id) => {
-            parent_to_expr(cx, stmt_id);
+            parent_to_expr(cx, stmt_id, stmt.span);
             let expr_cx = Context {parent: Some(stmt_id), ..cx};
             visit::visit_stmt(stmt, expr_cx, visitor);
         }
@@ -368,7 +370,7 @@ pub fn resolve_stmt(stmt: @ast::stmt, cx: Context, visitor: visit::vt<Context>)
 }
 
 pub fn resolve_expr(expr: @ast::expr, cx: Context, visitor: visit::vt<Context>) {
-    parent_to_expr(cx, expr.id);
+    parent_to_expr(cx, expr.id, expr.span);
 
     let mut new_cx = cx;
     new_cx.parent = Some(expr.id);
@@ -410,7 +412,7 @@ pub fn resolve_local(local: @ast::local,
                      cx: Context,
                      visitor: visit::vt<Context>) {
     assert_eq!(cx.var_parent, cx.parent);
-    parent_to_expr(cx, local.node.id);
+    parent_to_expr(cx, local.node.id, local.span);
     visit::visit_local(local, cx, visitor);
 }
 
@@ -423,12 +425,18 @@ pub fn resolve_item(item: @ast::item, cx: Context, visitor: visit::vt<Context>)
 pub fn resolve_fn(fk: &visit::fn_kind,
                   decl: &ast::fn_decl,
                   body: &ast::blk,
-                  _sp: span,
+                  sp: span,
                   id: ast::node_id,
                   cx: Context,
                   visitor: visit::vt<Context>) {
-    debug!("region::resolve_fn(id=%?, body.node.id=%?, cx.parent=%?)",
+    debug!("region::resolve_fn(id=%?, \
-           id, body.node.id, cx.parent);
+                               span=%?, \
+                               body.node.id=%?, \
+                               cx.parent=%?)",
+           id,
+           cx.sess.codemap.span_to_str(sp),
+           body.node.id,
+           cx.parent);
 
     // The arguments and `self` are parented to the body of the fn.
     let decl_cx = Context {parent: Some(body.node.id),

src/librustc/middle/trans/_match.rs

@@ -1282,7 +1282,8 @@ pub fn compile_submatch(bcx: block,
     assert!((m.len() > 0u || chk.is_some()));
     let _icx = bcx.insn_ctxt("match::compile_submatch");
     let mut bcx = bcx;
-    let tcx = bcx.tcx(), dm = tcx.def_map;
+    let tcx = bcx.tcx();
+    let dm = tcx.def_map;
     if m.len() == 0u {
         Br(bcx, chk.get()());
         return;
@@ -1638,7 +1639,8 @@ fn create_bindings_map(bcx: block, pat: @ast::pat) -> BindingsMap {
         let variable_ty = node_id_type(bcx, p_id);
         let llvariable_ty = type_of::type_of(ccx, variable_ty);
 
-        let llmatch, trmode;
+        let llmatch;
+        let trmode;
         match bm {
             ast::bind_infer => {
                 // in this case, the final type of the variable will be T,
@@ -1676,7 +1678,8 @@ pub fn trans_match_inner(scope_cx: block,
         return bcx;
     }
 
-    let mut arm_datas = ~[], matches = ~[];
+    let mut arm_datas = ~[];
+    let mut matches = ~[];
     for vec::each(arms) |arm| {
         let body = scope_block(bcx, arm.body.info(), "case_body");
         let bindings_map = create_bindings_map(bcx, arm.pats[0]);

src/librustc/middle/trans/base.rs

@@ -950,7 +950,8 @@ pub fn in_lpad_scope_cx(bcx: block, f: &fn(si: &mut scope_info)) {
 pub fn get_landing_pad(bcx: block) -> BasicBlockRef {
     let _icx = bcx.insn_ctxt("get_landing_pad");
 
-    let mut cached = None, pad_bcx = bcx; // Guaranteed to be set below
+    let mut cached = None;
+    let mut pad_bcx = bcx; // Guaranteed to be set below
     do in_lpad_scope_cx(bcx) |inf| {
         // If there is a valid landing pad still around, use it
         match inf.landing_pad {
@@ -1154,15 +1155,13 @@ pub fn trans_stmt(cx: block, s: &ast::stmt) -> block {
         }
         ast::stmt_decl(d, _) => {
             match d.node {
-                ast::decl_local(ref locals) => {
+                ast::decl_local(ref local) => {
-                    for locals.each |local| {
                     bcx = init_local(bcx, *local);
                     if cx.sess().opts.extra_debuginfo
                         && fcx_has_nonzero_span(bcx.fcx) {
                         debuginfo::create_local_var(bcx, *local);
                     }
                 }
-                }
                 ast::decl_item(i) => trans_item(*cx.fcx.ccx, i)
             }
         }
@@ -1296,7 +1295,8 @@ pub fn cleanup_and_leave(bcx: block,
                          upto: Option<BasicBlockRef>,
                          leave: Option<BasicBlockRef>) {
     let _icx = bcx.insn_ctxt("cleanup_and_leave");
-    let mut cur = bcx, bcx = bcx;
+    let mut cur = bcx;
+    let mut bcx = bcx;
     let is_lpad = leave == None;
     loop {
         debug!("cleanup_and_leave: leaving %s", cur.to_str());
@@ -1402,15 +1402,11 @@ pub fn block_locals(b: &ast::blk, it: &fn(@ast::local)) {
         match s.node {
           ast::stmt_decl(d, _) => {
             match d.node {
-              ast::decl_local(ref locals) => {
+              ast::decl_local(ref local) => it(*local),
-                for locals.each |local| {
+              _ => {} /* fall through */
-                    it(*local);
             }
           }
-              _ => {/* fall through */ }
+          _ => {} /* fall through */
-            }
-          }
-          _ => {/* fall through */ }
         }
     }
 }
@@ -1987,7 +1983,8 @@ pub fn trans_enum_variant(ccx: @CrateContext,
                                None);
 
     let raw_llargs = create_llargs_for_fn_args(fcx, no_self, fn_args);
-    let bcx = top_scope_block(fcx, None), lltop = bcx.llbb;
+    let bcx = top_scope_block(fcx, None);
+    let lltop = bcx.llbb;
     let arg_tys = ty::ty_fn_args(node_id_type(bcx, variant.node.id));
     let bcx = copy_args_to_allocas(fcx, bcx, fn_args, raw_llargs, arg_tys);
 

src/librustc/middle/trans/closure.rs

@@ -161,7 +161,8 @@ pub fn mk_closure_tys(tcx: ty::ctxt,
 pub fn allocate_cbox(bcx: block, sigil: ast::Sigil, cdata_ty: ty::t)
                   -> Result {
     let _icx = bcx.insn_ctxt("closure::allocate_cbox");
-    let ccx = bcx.ccx(), tcx = ccx.tcx;
+    let ccx = bcx.ccx();
+    let tcx = ccx.tcx;
 
     fn nuke_ref_count(bcx: block, llbox: ValueRef) {
         let _icx = bcx.insn_ctxt("closure::nuke_ref_count");
@@ -204,7 +205,8 @@ pub fn store_environment(bcx: block,
                          bound_values: ~[EnvValue],
                          sigil: ast::Sigil) -> ClosureResult {
     let _icx = bcx.insn_ctxt("closure::store_environment");
-    let ccx = bcx.ccx(), tcx = ccx.tcx;
+    let ccx = bcx.ccx();
+    let tcx = ccx.tcx;
 
     // compute the shape of the closure
     let cdata_ty = mk_closure_tys(tcx, bound_values);
@@ -500,7 +502,8 @@ pub fn make_opaque_cbox_take_glue(
     }
 
     // ~fn requires a deep copy.
-    let ccx = bcx.ccx(), tcx = ccx.tcx;
+    let ccx = bcx.ccx();
+    let tcx = ccx.tcx;
     let llopaquecboxty = T_opaque_box_ptr(ccx);
     let cbox_in = Load(bcx, cboxptr);
     do with_cond(bcx, IsNotNull(bcx, cbox_in)) |bcx| {

src/librustc/middle/trans/common.rs

@@ -1438,7 +1438,8 @@ pub fn align_to(cx: block, off: ValueRef, align: ValueRef) -> ValueRef {
 }
 
 pub fn path_str(sess: session::Session, p: &[path_elt]) -> ~str {
-    let mut r = ~"", first = true;
+    let mut r = ~"";
+    let mut first = true;
     for p.each |e| {
         match *e {
             ast_map::path_name(s) | ast_map::path_mod(s) => {

src/librustc/middle/trans/controlflow.rs

@@ -332,7 +332,8 @@ pub fn trans_fail_expr(bcx: block,
     let mut bcx = bcx;
     match fail_expr {
         Some(arg_expr) => {
-            let ccx = bcx.ccx(), tcx = ccx.tcx;
+            let ccx = bcx.ccx();
+            let tcx = ccx.tcx;
             let arg_datum = unpack_datum!(
                 bcx, expr::trans_to_datum(bcx, arg_expr));
 

src/librustc/middle/trans/debuginfo.rs

@@ -881,7 +881,8 @@ pub fn create_local_var(bcx: block, local: @ast::local)
 
 pub fn create_arg(bcx: block, arg: ast::arg, sp: span)
     -> Option<@Metadata<ArgumentMetadata>> {
-    let fcx = bcx.fcx, cx = *fcx.ccx;
+    let fcx = bcx.fcx;
+    let cx = *fcx.ccx;
     let cache = get_cache(cx);
     let tg = ArgVariableTag;
     match cached_metadata::<@Metadata<ArgumentMetadata>>(

src/librustc/middle/trans/foreign.rs

@@ -436,7 +436,8 @@ pub fn trans_foreign_mod(ccx: @CrateContext,
         debug!("build_direct_fn(%s)", *link_name(ccx, item));
 
         let fcx = new_fn_ctxt(ccx, ~[], decl, tys.fn_sig.output, None);
-        let bcx = top_scope_block(fcx, None), lltop = bcx.llbb;
+        let bcx = top_scope_block(fcx, None);
+        let lltop = bcx.llbb;
         let llbasefn = base_fn(ccx, *link_name(ccx, item), tys, cc);
         let ty = ty::lookup_item_type(ccx.tcx,
                                       ast_util::local_def(item.id)).ty;
@@ -462,7 +463,8 @@ pub fn trans_foreign_mod(ccx: @CrateContext,
         debug!("build_fast_ffi_fn(%s)", *link_name(ccx, item));
 
         let fcx = new_fn_ctxt(ccx, ~[], decl, tys.fn_sig.output, None);
-        let bcx = top_scope_block(fcx, None), lltop = bcx.llbb;
+        let bcx = top_scope_block(fcx, None);
+        let lltop = bcx.llbb;
         let llbasefn = base_fn(ccx, *link_name(ccx, item), tys, cc);
         set_no_inline(fcx.llfn);
         set_fixed_stack_segment(fcx.llfn);

src/librustc/middle/trans/meth.rs

@@ -566,7 +566,8 @@ pub fn combine_impl_and_methods_origins(bcx: block,
     // Find the bounds for the method, which are the tail of the
     // bounds found in the item type, as the item type combines the
     // rcvr + method bounds.
-    let ccx = bcx.ccx(), tcx = bcx.tcx();
+    let ccx = bcx.ccx();
+    let tcx = bcx.tcx();
     let n_m_tps = method_ty_param_count(ccx, mth_did, impl_did);
     let ty::ty_param_bounds_and_ty {
         generics: r_m_generics,

src/librustc/middle/trans/tvec.rs

@@ -136,7 +136,8 @@ pub fn duplicate_uniq(bcx: block, vptr: ValueRef, vec_ty: ty::t) -> Result {
 pub fn make_drop_glue_unboxed(bcx: block, vptr: ValueRef, vec_ty: ty::t) ->
    block {
     let _icx = bcx.insn_ctxt("tvec::make_drop_glue_unboxed");
-    let tcx = bcx.tcx(), unit_ty = ty::sequence_element_type(tcx, vec_ty);
+    let tcx = bcx.tcx();
+    let unit_ty = ty::sequence_element_type(tcx, vec_ty);
     if ty::type_needs_drop(tcx, unit_ty) {
         iter_vec_unboxed(bcx, vptr, vec_ty, glue::drop_ty)
     } else { bcx }

src/librustc/middle/typeck/check/_match.rs

@@ -106,7 +106,8 @@ pub fn check_pat_variant(pcx: &pat_ctxt, pat: @ast::pat, path: @ast::Path,
     let fcx = pcx.fcx;
     let tcx = pcx.fcx.ccx.tcx;
 
-    let arg_types, kind_name;
+    let arg_types;
+    let kind_name;
 
     // structure_of requires type variables to be resolved.
     // So when we pass in <expected>, it's an error if it

src/librustc/middle/typeck/check/mod.rs

@@ -1896,7 +1896,9 @@ pub fn check_expr_with_unifier(fcx: @mut FnCtxt,
 
         // Look up the number of type parameters and the raw type, and
         // determine whether the class is region-parameterized.
-        let type_parameter_count, region_parameterized, raw_type;
+        let type_parameter_count;
+        let region_parameterized;
+        let raw_type;
         if class_id.crate == ast::local_crate {
             region_parameterized =
                 tcx.region_paramd_items.find(&class_id.node).
@@ -1983,7 +1985,9 @@ pub fn check_expr_with_unifier(fcx: @mut FnCtxt,
 
         // Look up the number of type parameters and the raw type, and
         // determine whether the enum is region-parameterized.
-        let type_parameter_count, region_parameterized, raw_type;
+        let type_parameter_count;
+        let region_parameterized;
+        let raw_type;
         if enum_id.crate == ast::local_crate {
             region_parameterized =
                 tcx.region_paramd_items.find(&enum_id.node).map_consume(|x| *x);
@@ -2876,12 +2880,12 @@ pub fn check_stmt(fcx: @mut FnCtxt, stmt: @ast::stmt)  {
       ast::stmt_decl(decl, id) => {
         node_id = id;
         match decl.node {
-          ast::decl_local(ref ls) => for ls.each |l| {
+          ast::decl_local(ref l) => {
               check_decl_local(fcx, *l);
               let l_t = fcx.node_ty(l.node.id);
               saw_bot = saw_bot || ty::type_is_bot(l_t);
               saw_err = saw_err || ty::type_is_error(l_t);
-          },
+          }
           ast::decl_item(_) => {/* ignore for now */ }
         }
       }

src/librustc/middle/typeck/check/vtable.rs

@@ -88,7 +88,8 @@ fn lookup_vtables(vcx: &VtableContext,
     let _i = indenter();
 
     let tcx = vcx.tcx();
-    let mut result = ~[], i = 0u;
+    let mut result = ~[];
+    let mut i = 0u;
     for substs.tps.each |ty| {
         // ty is the value supplied for the type parameter A...
 

src/librustc/middle/typeck/check/writeback.rs

@@ -107,7 +107,8 @@ fn resolve_vtable_map_entry(fcx: @mut FnCtxt, sp: span, id: ast::node_id) {
 
 fn resolve_type_vars_for_node(wbcx: @mut WbCtxt, sp: span, id: ast::node_id)
                            -> Option<ty::t> {
-    let fcx = wbcx.fcx, tcx = fcx.ccx.tcx;
+    let fcx = wbcx.fcx;
+    let tcx = fcx.ccx.tcx;
 
     // Resolve any borrowings for the node with id `id`
     match fcx.inh.adjustments.find(&id) {

src/librustc/middle/typeck/infer/glb.rs

@@ -220,7 +220,9 @@ impl Combine for Glb {
 
             let tainted = this.infcx.region_vars.tainted(snapshot, r0);
 
-            let mut a_r = None, b_r = None, only_new_vars = true;
+            let mut a_r = None;
+            let mut b_r = None;
+            let mut only_new_vars = true;
             for tainted.each |r| {
                 if is_var_in_set(a_vars, *r) {
                     if a_r.is_some() {

src/librustc/middle/typeck/infer/lattice.rs

@@ -422,7 +422,7 @@ pub fn lattice_vars<L:LatticeDir + Combine,
 
     // If both A and B have an UB type, then we can just compute the
     // LUB of those types:
-    let a_bnd = this.bnd(a_bounds), b_bnd = this.bnd(b_bounds);
+    let (a_bnd, b_bnd) = (this.bnd(a_bounds), this.bnd(b_bounds));
     match (a_bnd, b_bnd) {
         (Some(ref a_ty), Some(ref b_ty)) => {
             match this.infcx().try(|| lattice_dir_op(a_ty, b_ty) ) {

src/librustc/middle/typeck/infer/region_inference.rs

@@ -928,7 +928,8 @@ impl RegionVarBindings {
         // `result_set` acts as a worklist: we explore all outgoing
         // edges and add any new regions we find to result_set.  This
         // is not a terribly efficient implementation.
-        let mut result_set = ~[r0], result_index = 0;
+        let mut result_set = ~[r0];
+        let mut result_index = 0;
         while result_index < result_set.len() {
             // nb: can't use uint::range() here because result_set grows
             let r = result_set[result_index];

src/librustc/middle/typeck/mod.rs

@@ -242,7 +242,8 @@ pub fn require_same_types(
     t2: ty::t,
     msg: &fn() -> ~str) -> bool {
 
-    let l_tcx, l_infcx;
+    let l_tcx;
+    let l_infcx;
     match maybe_infcx {
       None => {
         l_tcx = tcx;

src/libstd/io.rs

@@ -771,7 +771,7 @@ impl<T:Reader> ReaderUtil for T {
     fn read_le_uint_n(&self, nbytes: uint) -> u64 {
         assert!(nbytes > 0 && nbytes <= 8);
 
-        let mut val = 0u64, pos = 0, i = nbytes;
+        let mut (val, pos, i) = (0u64, 0, nbytes);
         while i > 0 {
             val += (self.read_u8() as u64) << pos;
             pos += 8;
@@ -787,7 +787,7 @@ impl<T:Reader> ReaderUtil for T {
     fn read_be_uint_n(&self, nbytes: uint) -> u64 {
         assert!(nbytes > 0 && nbytes <= 8);
 
-        let mut val = 0u64, i = nbytes;
+        let mut (val, i) = (0u64, nbytes);
         while i > 0 {
             i -= 1;
             val += (self.read_u8() as u64) << i * 8;
@@ -1304,7 +1304,9 @@ pub fn u64_to_le_bytes<T>(n: u64, size: uint,
               (n >> 56) as u8]),
       _ => {
 
-        let mut bytes: ~[u8] = ~[], i = size, n = n;
+        let mut bytes: ~[u8] = ~[];
+        let mut i = size;
+        let mut n = n;
         while i > 0u {
             bytes.push((n & 255_u64) as u8);
             n >>= 8_u64;

src/libstd/managed.rs

@@ -40,14 +40,14 @@ pub mod raw {
 /// Determine if two shared boxes point to the same object
 #[inline(always)]
 pub fn ptr_eq<T>(a: @T, b: @T) -> bool {
-    let a_ptr: *T = to_unsafe_ptr(&*a), b_ptr: *T = to_unsafe_ptr(&*b);
+    let (a_ptr, b_ptr): (*T, *T) = (to_unsafe_ptr(&*a), to_unsafe_ptr(&*b));
     a_ptr == b_ptr
 }
 
 /// Determine if two mutable shared boxes point to the same object
 #[inline(always)]
 pub fn mut_ptr_eq<T>(a: @mut T, b: @mut T) -> bool {
-    let a_ptr: *T = to_unsafe_ptr(&*a), b_ptr: *T = to_unsafe_ptr(&*b);
+    let (a_ptr, b_ptr): (*T, *T) = (to_unsafe_ptr(&*a), to_unsafe_ptr(&*b));
     a_ptr == b_ptr
 }
 

src/libstd/num/int_macros.rs

@@ -400,7 +400,7 @@ impl Integer for $T {
     #[inline(always)]
     fn gcd(&self, other: &$T) -> $T {
         // Use Euclid's algorithm
-        let mut m = *self, n = *other;
+        let mut (m, n) = (*self, *other);
         while m != 0 {
             let temp = m;
             m = n % temp;

src/libstd/num/uint_macros.rs

@@ -237,7 +237,7 @@ impl Integer for $T {
     #[inline(always)]
     fn gcd(&self, other: &$T) -> $T {
         // Use Euclid's algorithm
-        let mut m = *self, n = *other;
+        let mut (m, n) = (*self, *other);
         while m != 0 {
             let temp = m;
             m = n % temp;

src/libstd/rand.rs

@@ -658,13 +658,14 @@ impl IsaacRng {
     /// of `rsl` as a seed, otherwise construct one algorithmically (not
     /// randomly).
     fn init(&mut self, use_rsl: bool) {
-        macro_rules! init_mut_many (
+        let mut a = 0x9e3779b9;
-            ($( $var:ident ),* = $val:expr ) => {
+        let mut b = a;
-                let mut $( $var = $val ),*;
+        let mut c = a;
-            }
+        let mut d = a;
-        );
+        let mut e = a;
-        init_mut_many!(a, b, c, d, e, f, g, h = 0x9e3779b9);
+        let mut f = a;
-
+        let mut g = a;
+        let mut h = a;
 
         macro_rules! mix(
             () => {{
@@ -718,7 +719,7 @@ impl IsaacRng {
     fn isaac(&mut self) {
         self.c += 1;
         // abbreviations
-        let mut a = self.a, b = self.b + self.c;
+        let mut (a, b) = (self.a, self.b + self.c);
 
         static midpoint: uint = RAND_SIZE as uint / 2;
 

src/libstd/rand/distributions.rs

@@ -89,7 +89,7 @@ impl Rand for StandardNormal {
             // do-while, so the condition should be true on the first
             // run, they get overwritten anyway (0 < 1, so these are
             // good).
-            let mut x = 1.0, y = 0.0;
+            let mut (x, y) = (1.0, 0.0);
 
             // XXX infinities?
             while -2.0*y < x * x {

src/libstd/rt/io/extensions.rs

@@ -342,7 +342,7 @@ impl<T: Reader> ReaderByteConversions for T {
     fn read_le_uint_n(&mut self, nbytes: uint) -> u64 {
         assert!(nbytes > 0 && nbytes <= 8);
 
-        let mut val = 0u64, pos = 0, i = nbytes;
+        let mut (val, pos, i) = (0u64, 0, nbytes);
         while i > 0 {
             val += (self.read_u8() as u64) << pos;
             pos += 8;
@@ -358,7 +358,7 @@ impl<T: Reader> ReaderByteConversions for T {
     fn read_be_uint_n(&mut self, nbytes: uint) -> u64 {
         assert!(nbytes > 0 && nbytes <= 8);
 
-        let mut val = 0u64, i = nbytes;
+        let mut (val, i) = (0u64, nbytes);
         while i > 0 {
             i -= 1;
             val += (self.read_u8() as u64) << i * 8;

src/libstd/rt/uv/mod.rs

@@ -242,7 +242,7 @@ pub fn uv_error_to_io_error(uverr: UvError) -> IoError {
     // XXX: Could go in str::raw
     unsafe fn c_str_to_static_slice(s: *libc::c_char) -> &'static str {
         let s = s as *u8;
-        let mut curr = s, len = 0u;
+        let mut (curr, len) = (s, 0u);
         while *curr != 0u8 {
             len += 1u;
             curr = ptr::offset(s, len);

src/libstd/str.rs

@@ -661,9 +661,9 @@ fn each_split_char_inner<'a>(s: &'a str,
                              allow_trailing_empty: bool,
                              it: &fn(&'a str) -> bool) -> bool {
     if sep < 128u as char {
-        let b = sep as u8, l = len(s);
+        let (b, l) = (sep as u8, len(s));
         let mut done = 0u;
-        let mut i = 0u, start = 0u;
+        let mut (i, start) = (0u, 0u);
         while i < l && done < count {
             if s[i] == b {
                 if allow_empty || start < i {
@@ -725,7 +725,7 @@ fn each_split_inner<'a>(s: &'a str,
                         allow_trailing_empty: bool,
                         it: &fn(&'a str) -> bool) -> bool {
     let l = len(s);
-    let mut i = 0u, start = 0u, done = 0u;
+    let mut (i, start, done) = (0u, 0u, 0u);
     while i < l && done < count {
         let CharRange {ch, next} = char_range_at(s, i);
         if sepfn(ch) {
@@ -748,9 +748,9 @@ fn each_split_inner<'a>(s: &'a str,
 // See Issue #1932 for why this is a naive search
 fn iter_matches<'a,'b>(s: &'a str, sep: &'b str,
                        f: &fn(uint, uint) -> bool) -> bool {
-    let sep_len = len(sep), l = len(s);
+    let (sep_len, l) = (len(sep), len(s));
     assert!(sep_len > 0u);
-    let mut i = 0u, match_start = 0u, match_i = 0u;
+    let mut (i, match_start, match_i) = (0u, 0u, 0u);
 
     while i < l {
         if s[i] == sep[match_i] {
@@ -977,7 +977,7 @@ pub fn each_split_within<'a>(ss: &'a str,
  * The original string with all occurances of `from` replaced with `to`
  */
 pub fn replace(s: &str, from: &str, to: &str) -> ~str {
-    let mut result = ~"", first = true;
+    let mut (result, first) = (~"", true);
     for iter_between_matches(s, from) |start, end| {
         if first {
             first = false;
@@ -1761,7 +1761,7 @@ pub fn contains_char(haystack: &str, needle: char) -> bool {
  * * needle - The string to look for
  */
 pub fn starts_with<'a,'b>(haystack: &'a str, needle: &'b str) -> bool {
-    let haystack_len = len(haystack), needle_len = len(needle);
+    let (haystack_len, needle_len) = (len(haystack), len(needle));
     if needle_len == 0u { true }
     else if needle_len > haystack_len { false }
     else { match_at(haystack, needle, 0u) }
@@ -1776,7 +1776,7 @@ pub fn starts_with<'a,'b>(haystack: &'a str, needle: &'b str) -> bool {
  * * needle - The string to look for
  */
 pub fn ends_with<'a,'b>(haystack: &'a str, needle: &'b str) -> bool {
-    let haystack_len = len(haystack), needle_len = len(needle);
+    let (haystack_len, needle_len) = (len(haystack), len(needle));
     if needle_len == 0u { true }
     else if needle_len > haystack_len { false }
     else { match_at(haystack, needle, haystack_len - needle_len) }
@@ -1951,7 +1951,7 @@ pub fn with_capacity(capacity: uint) -> ~str {
 pub fn count_chars(s: &str, start: uint, end: uint) -> uint {
     assert!(is_char_boundary(s, start));
     assert!(is_char_boundary(s, end));
-    let mut i = start, len = 0u;
+    let mut (i, len) = (start, 0u);
     while i < end {
         let next = char_range_at(s, i).next;
         len += 1u;
@@ -1964,7 +1964,7 @@ pub fn count_chars(s: &str, start: uint, end: uint) -> uint {
 /// starting from `start`.
 pub fn count_bytes<'b>(s: &'b str, start: uint, n: uint) -> uint {
     assert!(is_char_boundary(s, start));
-    let mut end = start, cnt = n;
+    let mut (end, cnt) = (start, n);
     let l = len(s);
     while cnt > 0u {
         assert!(end < l);
@@ -2300,7 +2300,10 @@ pub fn as_buf<T>(s: &str, f: &fn(*u8, uint) -> T) -> T {
 pub fn subslice_offset(outer: &str, inner: &str) -> uint {
     do as_buf(outer) |a, a_len| {
         do as_buf(inner) |b, b_len| {
-            let a_start: uint, a_end: uint, b_start: uint, b_end: uint;
+            let a_start: uint;
+            let a_end: uint;
+            let b_start: uint;
+            let b_end: uint;
             unsafe {
                 a_start = cast::transmute(a); a_end = a_len + cast::transmute(a);
                 b_start = cast::transmute(b); b_end = b_len + cast::transmute(b);
@@ -2404,7 +2407,7 @@ pub mod raw {
 
     /// Create a Rust string from a null-terminated *u8 buffer
     pub unsafe fn from_buf(buf: *u8) -> ~str {
-        let mut curr = buf, i = 0u;
+        let mut (curr, i) = (buf, 0u);
         while *curr != 0u8 {
             i += 1u;
             curr = ptr::offset(buf, i);

src/libstd/to_str.rs

@@ -53,7 +53,7 @@ impl<A:ToStr> ToStr for (A,) {
 impl<A:ToStr+Hash+Eq, B:ToStr+Hash+Eq> ToStr for HashMap<A, B> {
     #[inline(always)]
     fn to_str(&self) -> ~str {
-        let mut acc = ~"{", first = true;
+        let mut (acc, first) = (~"{", true);
         for self.each |key, value| {
             if first {
                 first = false;
@@ -73,7 +73,7 @@ impl<A:ToStr+Hash+Eq, B:ToStr+Hash+Eq> ToStr for HashMap<A, B> {
 impl<A:ToStr+Hash+Eq> ToStr for HashSet<A> {
     #[inline(always)]
     fn to_str(&self) -> ~str {
-    let mut acc = ~"{", first = true;
+        let mut (acc, first) = (~"{", true);
         for self.each |element| {
             if first {
                 first = false;
@@ -121,7 +121,7 @@ impl<A:ToStr,B:ToStr,C:ToStr> ToStr for (A, B, C) {
 impl<'self,A:ToStr> ToStr for &'self [A] {
     #[inline(always)]
     fn to_str(&self) -> ~str {
-        let mut acc = ~"[", first = true;
+        let mut (acc, first) = (~"[", true);
         for self.each |elt| {
             if first {
                 first = false;
@@ -139,7 +139,7 @@ impl<'self,A:ToStr> ToStr for &'self [A] {
 impl<A:ToStr> ToStr for ~[A] {
     #[inline(always)]
     fn to_str(&self) -> ~str {
-        let mut acc = ~"[", first = true;
+        let mut (acc, first) = (~"[", true);
         for self.each |elt| {
             if first {
                 first = false;
@@ -157,7 +157,7 @@ impl<A:ToStr> ToStr for ~[A] {
 impl<A:ToStr> ToStr for @[A] {
     #[inline(always)]
     fn to_str(&self) -> ~str {
-        let mut acc = ~"[", first = true;
+        let mut (acc, first) = (~"[", true);
         for self.each |elt| {
             if first {
                 first = false;

src/libstd/tuple.rs

@@ -412,7 +412,7 @@ mod tests {
 
     #[test]
     fn test_tuple_cmp() {
-        let small = (1u, 2u, 3u), big = (3u, 2u, 1u);
+        let (small, big) = ((1u, 2u, 3u), (3u, 2u, 1u));
 
         // Eq
         assert_eq!(small, small);

src/libstd/vec.rs

@@ -749,7 +749,7 @@ pub fn truncate<T>(v: &mut ~[T], newlen: uint) {
 pub fn dedup<T:Eq>(v: &mut ~[T]) {
     unsafe {
         if v.len() < 1 { return; }
-        let mut last_written = 0, next_to_read = 1;
+        let mut (last_written, next_to_read) = (0, 1);
         do as_const_buf(*v) |p, ln| {
             // We have a mutable reference to v, so we can make arbitrary
             // changes. (cf. push and pop)
@@ -1365,7 +1365,7 @@ pub fn bsearch_elem<T:TotalOrd>(v: &[T], x: &T) -> Option<uint> {
  * Convert a vector of pairs into a pair of vectors, by reference. As unzip().
  */
 pub fn unzip_slice<T:Copy,U:Copy>(v: &[(T, U)]) -> (~[T], ~[U]) {
-    let mut ts = ~[], us = ~[];
+    let mut (ts, us) = (~[], ~[]);
     for each(v) |p| {
         let (t, u) = *p;
         ts.push(t);
@@ -1383,7 +1383,7 @@ pub fn unzip_slice<T:Copy,U:Copy>(v: &[(T, U)]) -> (~[T], ~[U]) {
  * of the i-th tuple of the input vector.
  */
 pub fn unzip<T,U>(v: ~[(T, U)]) -> (~[T], ~[U]) {
-    let mut ts = ~[], us = ~[];
+    let mut (ts, us) = (~[], ~[]);
     do consume(v) |_i, p| {
         let (t, u) = p;
         ts.push(t);

src/libsyntax/ast.rs

@@ -413,7 +413,10 @@ pub type local = spanned<local_>;
 pub type decl = spanned<decl_>;
 
 #[deriving(Eq, Encodable, Decodable)]
-pub enum decl_ { decl_local(~[@local]), decl_item(@item), }
+pub enum decl_ {
+    decl_local(@local),
+    decl_item(@item),
+}
 
 #[deriving(Eq, Encodable, Decodable)]
 pub struct arm {

src/libsyntax/ast_util.rs

@@ -279,7 +279,8 @@ pub fn trait_method_to_ty_method(method: &trait_method) -> ty_method {
 
 pub fn split_trait_methods(trait_methods: &[trait_method])
     -> (~[ty_method], ~[@method]) {
-    let mut reqd = ~[], provd = ~[];
+    let mut reqd = ~[];
+    let mut provd = ~[];
     for trait_methods.each |trt_method| {
         match *trt_method {
           required(ref tm) => reqd.push(copy *tm),

src/libsyntax/ext/build.rs

@@ -385,7 +385,7 @@ impl AstBuilder for @ExtCtxt {
                                 init: Some(ex),
                                 id: self.next_id(),
                             });
-        let decl = respan(sp, ast::decl_local(~[local]));
+        let decl = respan(sp, ast::decl_local(local));
         @respan(sp, ast::stmt_decl(@decl, self.next_id()))
     }
 

src/libsyntax/ext/deriving/generic.rs

@@ -416,7 +416,9 @@ impl<'self> MethodDef<'self> {
                              type_ident: ident, generics: &Generics)
         -> (ast::explicit_self, ~[@expr], ~[@expr], ~[(ident, @ast::Ty)]) {
 
-        let mut self_args = ~[], nonself_args = ~[], arg_tys = ~[];
+        let mut self_args = ~[];
+        let mut nonself_args = ~[];
+        let mut arg_tys = ~[];
         let mut nonstatic = false;
 
         let ast_explicit_self = match self.explicit_self {
@@ -522,8 +524,9 @@ impl<'self> MethodDef<'self> {
                                  nonself_args: &[@expr])
         -> @expr {
 
-        let mut raw_fields = ~[], // ~[[fields of self], [fields of next Self arg], [etc]]
+        let mut raw_fields = ~[]; // ~[[fields of self],
-                patterns = ~[];
+                                 // [fields of next Self arg], [etc]]
+        let mut patterns = ~[];
         for uint::range(0, self_args.len()) |i| {
             let (pat, ident_expr) = create_struct_pattern(cx, span,
                                                           type_ident, struct_def,

src/libsyntax/ext/deriving/mod.rs

@@ -264,8 +264,8 @@ pub fn create_struct_pattern(cx: @ExtCtxt,
 
     let matching_path = cx.path(span, ~[ struct_ident ]);
 
-    let mut paths = ~[], ident_expr = ~[];
+    let mut paths = ~[];
-
+    let mut ident_expr = ~[];
     let mut struct_type = Unknown;
 
     for struct_def.fields.eachi |i, struct_field| {
@@ -326,7 +326,8 @@ pub fn create_enum_variant_pattern(cx: @ExtCtxt,
 
             let matching_path = cx.path_ident(span, variant_ident);
 
-            let mut paths = ~[], ident_expr = ~[];
+            let mut paths = ~[];
+            let mut ident_expr = ~[];
             for uint::range(0, variant_args.len()) |i| {
                 let path = cx.path_ident(span,
                                          cx.ident_of(fmt!("%s_%u", prefix, i)));

src/libsyntax/ext/expand.rs

@@ -302,8 +302,9 @@ pub fn expand_stmt(extsbox: @mut SyntaxEnv,
                    s: &stmt_,
                    sp: span,
                    fld: @ast_fold,
-                   orig: @fn(&stmt_, span, @ast_fold) -> (stmt_, span))
+                   orig: @fn(&stmt_, span, @ast_fold)
-                -> (stmt_, span) {
+                             -> (Option<stmt_>, span))
+                -> (Option<stmt_>, span) {
     let (mac, pth, tts, semi) = match *s {
         stmt_mac(ref mac, semi) => {
             match mac.node {
@@ -342,8 +343,17 @@ pub fn expand_stmt(extsbox: @mut SyntaxEnv,
             };
 
             //keep going, outside-in
-            let fully_expanded = copy fld.fold_stmt(expanded).node;
+            let fully_expanded = match fld.fold_stmt(expanded) {
+                Some(stmt) => {
+                    let fully_expanded = &stmt.node;
                     cx.bt_pop();
+                    copy *fully_expanded
+                }
+                None => {
+                    cx.span_fatal(pth.span,
+                                  "macro didn't expand to a statement")
+                }
+            };
 
             (fully_expanded, sp)
         }
@@ -355,8 +365,8 @@ pub fn expand_stmt(extsbox: @mut SyntaxEnv,
     };
 
     (match fully_expanded {
-        stmt_expr(e, stmt_id) if semi => stmt_semi(e, stmt_id),
+        stmt_expr(e, stmt_id) if semi => Some(stmt_semi(e, stmt_id)),
-        _ => { fully_expanded } /* might already have a semi */
+        _ => { Some(fully_expanded) } /* might already have a semi */
     }, sp)
 
 }

src/libsyntax/fold.rs

@@ -26,10 +26,10 @@ pub trait ast_fold {
     fn fold_item_underscore(@self, &item_) -> item_;
     fn fold_method(@self, @method) -> @method;
     fn fold_block(@self, &blk) -> blk;
-    fn fold_stmt(@self, &stmt) -> @stmt;
+    fn fold_stmt(@self, &stmt) -> Option<@stmt>;
     fn fold_arm(@self, &arm) -> arm;
     fn fold_pat(@self, @pat) -> @pat;
-    fn fold_decl(@self, @decl) -> @decl;
+    fn fold_decl(@self, @decl) -> Option<@decl>;
     fn fold_expr(@self, @expr) -> @expr;
     fn fold_ty(@self, @Ty) -> @Ty;
     fn fold_mod(@self, &_mod) -> _mod;
@@ -55,10 +55,10 @@ pub struct AstFoldFns {
     fold_item_underscore: @fn(&item_, @ast_fold) -> item_,
     fold_method: @fn(@method, @ast_fold) -> @method,
     fold_block: @fn(&blk_, span, @ast_fold) -> (blk_, span),
-    fold_stmt: @fn(&stmt_, span, @ast_fold) -> (stmt_, span),
+    fold_stmt: @fn(&stmt_, span, @ast_fold) -> (Option<stmt_>, span),
     fold_arm: @fn(&arm, @ast_fold) -> arm,
     fold_pat: @fn(&pat_, span, @ast_fold) -> (pat_, span),
-    fold_decl: @fn(&decl_, span, @ast_fold) -> (decl_, span),
+    fold_decl: @fn(&decl_, span, @ast_fold) -> (Option<decl_>, span),
     fold_expr: @fn(&expr_, span, @ast_fold) -> (expr_, span),
     fold_ty: @fn(&ty_, span, @ast_fold) -> (ty_, span),
     fold_mod: @fn(&_mod, @ast_fold) -> _mod,
@@ -340,22 +340,39 @@ fn noop_fold_method(m: @method, fld: @ast_fold) -> @method {
 
 
 pub fn noop_fold_block(b: &blk_, fld: @ast_fold) -> blk_ {
+    let view_items = b.view_items.map(|x| fld.fold_view_item(*x));
+    let mut stmts = ~[];
+    for b.stmts.each |stmt| {
+        match fld.fold_stmt(*stmt) {
+            None => {}
+            Some(stmt) => stmts.push(stmt)
+        }
+    }
     ast::blk_ {
-        view_items: b.view_items.map(|x| fld.fold_view_item(*x)),
+        view_items: view_items,
-        stmts: b.stmts.map(|x| fld.fold_stmt(*x)),
+        stmts: stmts,
         expr: b.expr.map(|x| fld.fold_expr(*x)),
         id: fld.new_id(b.id),
         rules: b.rules,
     }
 }
 
-fn noop_fold_stmt(s: &stmt_, fld: @ast_fold) -> stmt_ {
+fn noop_fold_stmt(s: &stmt_, fld: @ast_fold) -> Option<stmt_> {
     let fold_mac = |x| fold_mac_(x, fld);
     match *s {
-        stmt_decl(d, nid) => stmt_decl(fld.fold_decl(d), fld.new_id(nid)),
+        stmt_decl(d, nid) => {
-        stmt_expr(e, nid) => stmt_expr(fld.fold_expr(e), fld.new_id(nid)),
+            match fld.fold_decl(d) {
-        stmt_semi(e, nid) => stmt_semi(fld.fold_expr(e), fld.new_id(nid)),
+                Some(d) => Some(stmt_decl(d, fld.new_id(nid))),
-        stmt_mac(ref mac, semi) => stmt_mac(fold_mac(mac), semi)
+                None => None,
+            }
+        }
+        stmt_expr(e, nid) => {
+            Some(stmt_expr(fld.fold_expr(e), fld.new_id(nid)))
+        }
+        stmt_semi(e, nid) => {
+            Some(stmt_semi(fld.fold_expr(e), fld.new_id(nid)))
+        }
+        stmt_mac(ref mac, semi) => Some(stmt_mac(fold_mac(mac), semi))
     }
 }
 
@@ -411,13 +428,13 @@ pub fn noop_fold_pat(p: &pat_, fld: @ast_fold) -> pat_ {
     }
 }
 
-fn noop_fold_decl(d: &decl_, fld: @ast_fold) -> decl_ {
+fn noop_fold_decl(d: &decl_, fld: @ast_fold) -> Option<decl_> {
     match *d {
-        decl_local(ref ls) => decl_local(ls.map(|x| fld.fold_local(*x))),
+        decl_local(ref l) => Some(decl_local(fld.fold_local(*l))),
         decl_item(it) => {
             match fld.fold_item(it) {
-                Some(it_folded) => decl_item(it_folded),
+                Some(it_folded) => Some(decl_item(it_folded)),
-                None => decl_local(~[]),
+                None => None,
             }
         }
     }
@@ -738,10 +755,10 @@ pub fn default_ast_fold() -> ast_fold_fns {
         fold_item_underscore: noop_fold_item_underscore,
         fold_method: noop_fold_method,
         fold_block: wrap(noop_fold_block),
-        fold_stmt: wrap(noop_fold_stmt),
+        fold_stmt: |x, s, fld| (noop_fold_stmt(x, fld), s),
         fold_arm: noop_fold_arm,
         fold_pat: wrap(noop_fold_pat),
-        fold_decl: wrap(noop_fold_decl),
+        fold_decl: |x, s, fld| (noop_fold_decl(x, fld), s),
         fold_expr: wrap(noop_fold_expr),
         fold_ty: wrap(noop_fold_ty),
         fold_mod: noop_fold_mod,
@@ -799,9 +816,12 @@ impl ast_fold for AstFoldFns {
         let (n, s) = (self.fold_block)(&x.node, x.span, self as @ast_fold);
         spanned { node: n, span: (self.new_span)(s) }
     }
-    fn fold_stmt(@self, x: &stmt) -> @stmt {
+    fn fold_stmt(@self, x: &stmt) -> Option<@stmt> {
-        let (n, s) = (self.fold_stmt)(&x.node, x.span, self as @ast_fold);
+        let (n_opt, s) = (self.fold_stmt)(&x.node, x.span, self as @ast_fold);
-        @spanned { node: n, span: (self.new_span)(s) }
+        match n_opt {
+            Some(n) => Some(@spanned { node: n, span: (self.new_span)(s) }),
+            None => None,
+        }
     }
     fn fold_arm(@self, x: &arm) -> arm {
         (self.fold_arm)(x, self as @ast_fold)
@@ -814,9 +834,12 @@ impl ast_fold for AstFoldFns {
             span: (self.new_span)(s),
         }
     }
-    fn fold_decl(@self, x: @decl) -> @decl {
+    fn fold_decl(@self, x: @decl) -> Option<@decl> {
-        let (n, s) = (self.fold_decl)(&x.node, x.span, self as @ast_fold);
+        let (n_opt, s) = (self.fold_decl)(&x.node, x.span, self as @ast_fold);
-        @spanned { node: n, span: (self.new_span)(s) }
+        match n_opt {
+            Some(n) => Some(@spanned { node: n, span: (self.new_span)(s) }),
+            None => None,
+        }
     }
     fn fold_expr(@self, x: @expr) -> @expr {
         let (n, s) = (self.fold_expr)(&x.node, x.span, self as @ast_fold);

src/libsyntax/parse/comments.rs

@@ -58,7 +58,8 @@ pub fn strip_doc_comment_decoration(comment: &str) -> ~str {
 
     /// remove whitespace-only lines from the start/end of lines
     fn vertical_trim(lines: ~[~str]) -> ~[~str] {
-        let mut i = 0u, j = lines.len();
+        let mut i = 0u;
+        let mut j = lines.len();
         while i < j && lines[i].trim().is_empty() {
             i += 1u;
         }

src/libsyntax/parse/lexer.rs

@@ -387,7 +387,10 @@ fn scan_digits(rdr: @mut StringReader, radix: uint) -> ~str {
 }
 
 fn scan_number(c: char, rdr: @mut StringReader) -> token::Token {
-    let mut num_str, base = 10u, c = c, n = nextch(rdr);
+    let mut num_str;
+    let mut base = 10u;
+    let mut c = c;
+    let mut n = nextch(rdr);
     if c == '0' && n == 'x' {
         bump(rdr);
         bump(rdr);
@@ -510,7 +513,8 @@ fn scan_number(c: char, rdr: @mut StringReader) -> token::Token {
 }
 
 fn scan_numeric_escape(rdr: @mut StringReader, n_hex_digits: uint) -> char {
-    let mut accum_int = 0, i = n_hex_digits;
+    let mut accum_int = 0;
+    let mut i = n_hex_digits;
     while i != 0u {
         let n = rdr.curr;
         bump(rdr);

src/libsyntax/parse/obsolete.rs

@@ -64,6 +64,7 @@ pub enum ObsoleteSyntax {
     ObsoleteConstItem,
     ObsoleteFixedLengthVectorType,
     ObsoleteNamedExternModule,
+    ObsoleteMultipleLocalDecl,
 }
 
 impl to_bytes::IterBytes for ObsoleteSyntax {
@@ -224,6 +225,11 @@ impl Parser {
                 "instead of `extern mod foo { ... }`, write `mod foo { \
                  extern { ... } }`"
             ),
+            ObsoleteMultipleLocalDecl => (
+                "declaration of multiple locals at once",
+                "instead of e.g. `let a = 1, b = 2`, write \
+                 `let (a, b) = (1, 2)`."
+            ),
         };
 
         self.report(sp, kind, kind_str, desc);

src/libsyntax/parse/parser.rs

@@ -84,7 +84,7 @@ use parse::obsolete::ObsoleteMode;
 use parse::obsolete::{ObsoleteLifetimeNotation, ObsoleteConstManagedPointer};
 use parse::obsolete::{ObsoletePurity, ObsoleteStaticMethod};
 use parse::obsolete::{ObsoleteConstItem, ObsoleteFixedLengthVectorType};
-use parse::obsolete::{ObsoleteNamedExternModule};
+use parse::obsolete::{ObsoleteNamedExternModule, ObsoleteMultipleLocalDecl};
 use parse::token::{can_begin_expr, is_ident, is_ident_or_path};
 use parse::token::{is_plain_ident, INTERPOLATED, keywords, special_idents, token_to_binop};
 use parse::token;
@@ -2573,11 +2573,12 @@ impl Parser {
     fn parse_let(&self) -> @decl {
         let is_mutbl = self.eat_keyword(keywords::Mut);
         let lo = self.span.lo;
-        let mut locals = ~[self.parse_local(is_mutbl)];
+        let mut local = self.parse_local(is_mutbl);
         while self.eat(&token::COMMA) {
-            locals.push(self.parse_local(is_mutbl));
+            let _ = self.parse_local(is_mutbl);
+            self.obsolete(*self.span, ObsoleteMultipleLocalDecl);
         }
-        return @spanned(lo, self.last_span.hi, decl_local(locals));
+        return @spanned(lo, self.last_span.hi, decl_local(local));
     }
 
     // parse a structure field
@@ -3840,15 +3841,18 @@ impl Parser {
     // parse the part of an "enum" decl following the '{'
     fn parse_enum_def(&self, _generics: &ast::Generics) -> enum_def {
         let mut variants = ~[];
-        let mut all_nullary = true, have_disr = false;
+        let mut all_nullary = true;
+        let mut have_disr = false;
         while *self.token != token::RBRACE {
             let variant_attrs = self.parse_outer_attributes();
             let vlo = self.span.lo;
 
             let vis = self.parse_visibility();
 
-            let ident, kind;
+            let ident;
-            let mut args = ~[], disr_expr = None;
+            let kind;
+            let mut args = ~[];
+            let mut disr_expr = None;
             ident = self.parse_ident();
             if self.eat(&token::LBRACE) {
                 // Parse a struct variant.
@@ -4352,7 +4356,8 @@ impl Parser {
     }
 
     fn is_view_item(&self) -> bool {
-        let tok, next_tok;
+        let tok;
+        let next_tok;
         if !self.is_keyword(keywords::Pub) && !self.is_keyword(keywords::Priv) {
             tok = copy *self.token;
             next_tok = self.look_ahead(1);

src/libsyntax/print/pprust.rs

@@ -1444,14 +1444,12 @@ pub fn print_local_decl(s: @ps, loc: @ast::local) {
 pub fn print_decl(s: @ps, decl: @ast::decl) {
     maybe_print_comment(s, decl.span.lo);
     match decl.node {
-      ast::decl_local(ref locs) => {
+      ast::decl_local(ref loc) => {
         space_if_not_bol(s);
         ibox(s, indent_unit);
         word_nbsp(s, "let");
 
-        // if any are mut, all are mut
+        if loc.node.is_mutbl {
-        if locs.any(|l| l.node.is_mutbl) {
-            assert!(locs.all(|l| l.node.is_mutbl));
             word_nbsp(s, "mut");
         }
 
@@ -1468,7 +1466,8 @@ pub fn print_decl(s: @ps, decl: @ast::decl) {
               _ => ()
             }
         }
-        commasep(s, consistent, *locs, print_local);
+
+        print_local(s, *loc);
         end(s);
       }
       ast::decl_item(item) => print_item(s, item)

src/libsyntax/visit.rs

@@ -430,11 +430,7 @@ pub fn visit_stmt<E>(s: @stmt, e: E, v: vt<E>) {
 
 pub fn visit_decl<E: Copy>(d: @decl, e: E, v: vt<E>) {
     match d.node {
-        decl_local(ref locs) => {
+        decl_local(ref loc) => (v.visit_local)(*loc, e, v),
-            for locs.each |loc| {
-                (v.visit_local)(*loc, e, v)
-            }
-        },
         decl_item(it) => (v.visit_item)(it, e, v)
     }
 }

src/test/bench/shootout-fannkuch-redux.rs

@@ -17,7 +17,9 @@ fn fannkuch_redux(n: i32) -> i32 {
     let mut perm = vec::from_elem(n as uint, 0i32);
     let mut perm1 = vec::from_fn(n as uint, |i| i as i32);
     let mut count = vec::from_elem(n as uint, 0i32);
-    let mut max_flips_count = 0i32, perm_count = 0i32, checksum = 0i32;
+    let mut max_flips_count = 0i32;
+    let mut perm_count = 0i32;
+    let mut checksum = 0i32;
 
     let mut r = n;
     loop {

src/test/bench/shootout-fasta-redux.rs

@@ -99,7 +99,9 @@ impl RepeatFasta {
                         alu,
                         LINE_LEN);
 
-            let mut pos = 0, bytes, n = n;
+            let mut pos = 0;
+            let mut bytes;
+            let mut n = n;
             while n > 0 {
                 bytes = min(LINE_LEN, n);
                 fwrite(transmute(&buf[pos]), bytes as size_t, 1, stdout);
@@ -158,7 +160,8 @@ impl RandomFasta {
 
     fn make(&mut self, n: uint) {
         unsafe {
-            let lines = n / LINE_LEN, chars_left = n % LINE_LEN;
+            let lines = n / LINE_LEN;
+            let chars_left = n % LINE_LEN;
             let mut buf = [0, ..LINE_LEN + 1];
 
             for lines.times {

src/test/bench/shootout-mandelbrot.rs

@@ -10,7 +10,8 @@ static LIMIT: f64 = 2.0;
 #[fixed_stack_segment]
 fn main() {
     unsafe {
-        let w: i32 = FromStr::from_str(os::args()[1]).get(), h = w;
+        let w: i32 = FromStr::from_str(os::args()[1]).get();
+        let h = w;
         let mut byte_acc: i8 = 0;
         let mut bit_num: i32 = 0;
 

src/test/bench/shootout-nbody.rs

@@ -92,7 +92,8 @@ fn advance(bodies: &mut [Planet, ..N_BODIES], dt: f64, steps: i32) {
                 let d2 = d[0]*d[0] + d[1]*d[1] + d[2]*d[2];
                 let mag = dt / (d2 * f64::sqrt(d2));
 
-                let a_mass = bodies[i].mass, b_mass = bodies[j].mass;
+                let a_mass = bodies[i].mass;
+                let b_mass = bodies[j].mass;
                 bodies[i].v[0] -= d[0] * b_mass * mag;
                 bodies[i].v[1] -= d[1] * b_mass * mag;
                 bodies[i].v[2] -= d[2] * b_mass * mag;

src/test/bench/shootout-spectralnorm.rs

@@ -45,7 +45,9 @@ fn mult_AtAv(v: &mut [f64], out: &mut [f64], tmp: &mut [f64]) {
 #[fixed_stack_segment]
 fn main() {
     let n: uint = FromStr::from_str(os::args()[1]).get();
-    let mut u = vec::from_elem(n, 1f64), v = u.clone(), tmp = u.clone();
+    let mut u = vec::from_elem(n, 1f64);
+    let mut v = u.clone();
+    let mut tmp = u.clone();
     for 8.times {
         mult_AtAv(u, v, tmp);
         mult_AtAv(v, u, tmp);

src/test/compile-fail/borrowck-lend-flow-loop.rs

@@ -49,7 +49,8 @@ fn block_overarching_alias_mut() {
 fn loop_aliased_mut() {
     // In this instance, the borrow is carried through the loop.
 
-    let mut v = ~3, w = ~4;
+    let mut v = ~3;
+    let mut w = ~4;
     let mut _x = &w;
     loop {
         borrow_mut(v); //~ ERROR cannot borrow
@@ -60,7 +61,8 @@ fn loop_aliased_mut() {
 fn while_aliased_mut() {
     // In this instance, the borrow is carried through the loop.
 
-    let mut v = ~3, w = ~4;
+    let mut v = ~3;
+    let mut w = ~4;
     let mut _x = &w;
     while cond() {
         borrow_mut(v); //~ ERROR cannot borrow
@@ -71,7 +73,8 @@ fn while_aliased_mut() {
 fn for_loop_aliased_mut() {
     // In this instance, the borrow is carried through the loop.
 
-    let mut v = ~3, w = ~4;
+    let mut v = ~3;
+    let mut w = ~4;
     let mut _x = &w;
     for for_func {
         borrow_mut(v); //~ ERROR cannot borrow
@@ -82,7 +85,8 @@ fn for_loop_aliased_mut() {
 fn loop_aliased_mut_break() {
     // In this instance, the borrow is carried through the loop.
 
-    let mut v = ~3, w = ~4;
+    let mut v = ~3;
+    let mut w = ~4;
     let mut _x = &w;
     loop {
         borrow_mut(v);
@@ -95,7 +99,8 @@ fn loop_aliased_mut_break() {
 fn while_aliased_mut_break() {
     // In this instance, the borrow is carried through the loop.
 
-    let mut v = ~3, w = ~4;
+    let mut v = ~3;
+    let mut w = ~4;
     let mut _x = &w;
     while cond() {
         borrow_mut(v);
@@ -108,7 +113,8 @@ fn while_aliased_mut_break() {
 fn for_aliased_mut_break() {
     // In this instance, the borrow is carried through the loop.
 
-    let mut v = ~3, w = ~4;
+    let mut v = ~3;
+    let mut w = ~4;
     let mut _x = &w;
     for for_func {
         // here we cannot be sure that `for_func` respects the break below
@@ -120,7 +126,8 @@ fn for_aliased_mut_break() {
 }
 
 fn while_aliased_mut_cond(cond: bool, cond2: bool) {
-    let mut v = ~3, w = ~4;
+    let mut v = ~3;
+    let mut w = ~4;
     let mut x = &mut w;
     while cond {
         **x += 1;

src/test/compile-fail/borrowck-uniq-via-lend.rs

@@ -48,13 +48,15 @@ fn aliased_mut() {
 }
 
 fn aliased_other() {
-    let mut v = ~3, w = ~4;
+    let mut v = ~3;
+    let mut w = ~4;
     let _x = &mut w;
     borrow(v);
 }
 
 fn aliased_other_reassign() {
-    let mut v = ~3, w = ~4;
+    let mut v = ~3;
+    let mut w = ~4;
     let mut _x = &mut w;
     _x = &mut v;
     borrow(v); //~ ERROR cannot borrow `*v`

src/test/compile-fail/issue-3021-d.rs

@@ -23,8 +23,8 @@ fn siphash(k0 : u64, k1 : u64) -> siphash {
 
     fn mk_result(st : SipState) -> u64 {
 
-        let v0 = st.v0,
+        let v0 = st.v0;
-            v1 = st.v1;
+        let v1 = st.v1;
         return v0 ^ v1;
     }
 

src/test/compile-fail/lint-unused-mut-variables.rs

@@ -17,8 +17,8 @@
 fn main() {
     // negative cases
     let mut a = 3; //~ ERROR: variable does not need to be mutable
-    let mut a = 2, b = 3; //~ ERROR: variable does not need to be mutable
+    let mut a = 2; //~ ERROR: variable does not need to be mutable
-                          //~^ ERROR: variable does not need to be mutable
+    let mut b = 3; //~ ERROR: variable does not need to be mutable
     let mut a = ~[3]; //~ ERROR: variable does not need to be mutable
 
     // positive cases

src/test/compile-fail/moves-based-on-type-exprs.rs

@@ -26,7 +26,8 @@ fn f21() {
 }
 
 fn f30(cond: bool) {
-    let x = ~"hi", y = ~"ho";
+    let x = ~"hi";
+    let y = ~"ho";
     let _y = if cond {
         x
     } else {
@@ -37,7 +38,8 @@ fn f30(cond: bool) {
 }
 
 fn f40(cond: bool) {
-    let x = ~"hi", y = ~"ho";
+    let x = ~"hi";
+    let y = ~"ho";
     let _y = match cond {
         true => x,
         false => y
@@ -47,7 +49,8 @@ fn f40(cond: bool) {
 }
 
 fn f50(cond: bool) {
-    let x = ~"hi", y = ~"ho";
+    let x = ~"hi";
+    let y = ~"ho";
     let _y = match cond {
         _ if guard(x) => 10,
         true => 10,

src/test/run-fail/issue-3029.rs

@@ -10,7 +10,8 @@
 
 // error-pattern:so long
 fn main() {
-    let x = ~[], y = ~[3];
+    let x = ~[];
+    let y = ~[3];
     fail!("so long");
     x += y;
     ~"good" + ~"bye";

src/test/run-fail/zip-different-lengths.rs

@@ -31,7 +31,10 @@ fn enum_uints(start: uint, end: uint) -> ~[uint] {
 }
 
 fn main() {
-    let a = 'a' as u8, j = 'j' as u8, k = 1, l = 9;
+    let a = 'a' as u8;
+    let j = 'j' as u8;
+    let k = 1;
+    let l = 9;
     let chars = enum_chars(a, j);
     let ints = enum_uints(k, l);
 

src/test/run-pass/argument-passing.rs

@@ -24,7 +24,9 @@ fn f1(a: &mut X, b: &mut int, c: int) -> int {
 fn f2(a: int, f: &fn(int)) -> int { f(1); return a; }
 
 pub fn main() {
-    let mut a = X {x: 1}, b = 2, c = 3;
+    let mut a = X {x: 1};
+    let mut b = 2;
+    let mut c = 3;
     assert_eq!(f1(&mut a, &mut b, c), 6);
     assert_eq!(a.x, 0);
     assert_eq!(b, 10);

src/test/run-pass/borrowck-preserve-cond-box.rs

@@ -17,7 +17,8 @@ fn testfn(cond: bool) {
     // borrow x and y
     let mut r_x = &*x;
     let mut r_y = &*y;
-    let mut r = r_x, exp = 3;
+    let mut r = r_x;
+    let mut exp = 3;
 
     if cond {
         r = r_y;

src/test/run-pass/deriving-cmp-generic-enum.rs

@@ -16,7 +16,11 @@ enum E<T> {
 }
 
 pub fn main() {
-    let e0 = E0, e11 = E1(1), e12 = E1(2), e21 = E2(1,1), e22 = E2(1, 2);
+    let e0 = E0;
+    let e11 = E1(1);
+    let e12 = E1(2);
+    let e21 = E2(1, 1);
+    let e22 = E2(1, 2);
 
     // in order for both Ord and TotalOrd
     let es = [e0, e11, e12, e21, e22];
@@ -26,8 +30,10 @@ pub fn main() {
             let ord = i.cmp(&j);
 
             let eq = i == j;
-            let lt = i < j, le = i <= j;
+            let lt = i < j;
-            let gt = i > j, ge = i >= j;
+            let le = i <= j;
+            let gt = i > j;
+            let ge = i >= j;
 
             // Eq
             assert_eq!(*e1 == *e2, eq);

src/test/run-pass/deriving-cmp-generic-struct.rs

@@ -15,7 +15,8 @@ struct S<T> {
 }
 
 pub fn main() {
-    let s1 = S {x: 1, y: 1}, s2 = S {x: 1, y: 2};
+    let s1 = S {x: 1, y: 1};
+    let s2 = S {x: 1, y: 2};
 
     // in order for both Ord and TotalOrd
     let ss = [s1, s2];
@@ -25,8 +26,10 @@ pub fn main() {
             let ord = i.cmp(&j);
 
             let eq = i == j;
-            let lt = i < j, le = i <= j;
+            let lt = i < j;
-            let gt = i > j, ge = i >= j;
+            let le = i <= j;
+            let gt = i > j;
+            let ge = i >= j;
 
             // Eq
             assert_eq!(*s1 == *s2, eq);

src/test/run-pass/deriving-cmp-generic-tuple-struct.rs

@@ -13,7 +13,8 @@ struct TS<T>(T,T);
 
 
 pub fn main() {
-    let ts1 = TS(1, 1), ts2 = TS(1,2);
+    let ts1 = TS(1, 1);
+    let ts2 = TS(1, 2);
 
     // in order for both Ord and TotalOrd
     let tss = [ts1, ts2];
@@ -23,8 +24,10 @@ pub fn main() {
             let ord = i.cmp(&j);
 
             let eq = i == j;
-            let lt = i < j, le = i <= j;
+            let lt = i < j;
-            let gt = i > j, ge = i >= j;
+            let le = i <= j;
+            let gt = i > j;
+            let ge = i >= j;
 
             // Eq
             assert_eq!(*ts1 == *ts2, eq);

src/test/run-pass/deriving-self-lifetime.rs

@@ -14,7 +14,8 @@ struct A<'self> {
 }
 
 fn main() {
-    let a = A { x: &1 }, b = A { x: &2 };
+    let a = A { x: &1 };
+    let b = A { x: &2 };
 
     assert_eq!(a, a);
     assert_eq!(b, b);

src/test/run-pass/multi-let.rs

@@ -8,4 +8,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-pub fn main() { let x = 10, y = x; assert!((y == 10)); }
+pub fn main() {
+    let x = 10;
+    let y = x;
+    assert!((y == 10));
+}
+

src/test/run-pass/pass-by-copy.rs

@@ -14,7 +14,8 @@ fn magic2(x: @int) { debug!(x); }
 struct A { a: @int }
 
 pub fn main() {
-    let a = A {a: @10}, b = @10;
+    let a = A {a: @10};
+    let b = @10;
     magic(a); magic(A {a: @20});
     magic2(b); magic2(@20);
 }

src/test/run-pass/pure-sum.rs

@@ -11,7 +11,8 @@
 // Check that functions can modify local state.
 
 fn sums_to(v: ~[int], sum: int) -> bool {
-    let mut i = 0u, sum0 = 0;
+    let mut i = 0u;
+    let mut sum0 = 0;
     while i < v.len() {
         sum0 += v[i];
         i += 1u;
@@ -20,7 +21,8 @@ fn sums_to(v: ~[int], sum: int) -> bool {
 }
 
 fn sums_to_using_uniq(v: ~[int], sum: int) -> bool {
-    let mut i = 0u, sum0 = ~0;
+    let mut i = 0u;
+    let mut sum0 = ~0;
     while i < v.len() {
         *sum0 += v[i];
         i += 1u;
@@ -29,7 +31,8 @@ fn sums_to_using_uniq(v: ~[int], sum: int) -> bool {
 }
 
 fn sums_to_using_rec(v: ~[int], sum: int) -> bool {
-    let mut i = 0u, sum0 = F {f: 0};
+    let mut i = 0u;
+    let mut sum0 = F {f: 0};
     while i < v.len() {
         sum0.f += v[i];
         i += 1u;
@@ -40,7 +43,8 @@ fn sums_to_using_rec(v: ~[int], sum: int) -> bool {
 struct F<T> { f: T }
 
 fn sums_to_using_uniq_rec(v: ~[int], sum: int) -> bool {
-    let mut i = 0u, sum0 = F {f: ~0};
+    let mut i = 0u;
+    let mut sum0 = F {f: ~0};
     while i < v.len() {
         *sum0.f += v[i];
         i += 1u;

src/test/run-pass/ret-break-cont-in-block.rs

@@ -14,7 +14,8 @@ use std::cmp::Eq;
 use std::vec;
 
 fn iter<T>(v: ~[T], it: &fn(&T) -> bool) -> bool {
-    let mut i = 0u, l = v.len();
+    let mut i = 0u;
+    let mut l = v.len();
     while i < l {
         if !it(&v[i]) { return false; }
         i += 1u;

src/test/run-pass/typestate-multi-decl.rs

@@ -8,4 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-pub fn main() { let x = 10, y = 20; let z = x + y; assert!((z == 30)); }
+pub fn main() {
+    let (x, y) = (10, 20);
+    let z = x + y;
+    assert!((z == 30));
+}

src/test/run-pass/zip-same-length.rs

@@ -30,7 +30,10 @@ fn enum_uints(start: uint, end: uint) -> ~[uint] {
 }
 
 pub fn main() {
-    let a = 'a' as u8, j = 'j' as u8, k = 1u, l = 10u;
+    let a = 'a' as u8;
+    let j = 'j' as u8;
+    let k = 1u;
+    let l = 10u;
     let chars = enum_chars(a, j);
     let ints = enum_uints(k, l);