Switch all vases of vec += elt to vec += vec. Prohibit former in rustboot. Tweak std lib vec fns in process.

29 files changed, 278 insertions, 225 deletions

diff --git a/src/Makefile b/src/Makefile
index 67a8743e..d063fb05 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -469,7 +469,6 @@ TEST_XFAILS_RUSTC := $(addprefix test/run-pass/, \
                         acyclic-unwind.rs \
                         alt-pattern-drop.rs \
                         alt-type-simple.rs \
-                        append-units.rs \
                         basic-1.rs \
                         basic-2.rs \
                         basic.rs \
diff --git a/src/boot/me/type.ml b/src/boot/me/type.ml
index 87e8e4c1..72bdd404 100644
--- a/src/boot/me/type.ml
+++ b/src/boot/me/type.ml
@@ -993,8 +993,7 @@ let check_block (cx:Semant.ctxt) : (fn_ctx -> Ast.block -> unit) =
             let src_ty = check_atom ~deref:true src in
             let dst_ty = check_lval dst in
               match fundamental_ty dst_ty, fundamental_ty src_ty with
-                  Ast.TY_vec elt1, Ast.TY_vec elt2
-                | Ast.TY_vec elt1, elt2 ->
+                  Ast.TY_vec elt1, Ast.TY_vec elt2 ->
                     if elt1 = elt2
                     then ()
                     else
@@ -1002,7 +1001,6 @@ let check_block (cx:Semant.ctxt) : (fn_ctx -> Ast.block -> unit) =
                         "mismatched types in vec-append: %s += %s"
                         (pretty_ty_str dst_ty)
                         (pretty_ty_str src_ty)
-                | Ast.TY_str, (Ast.TY_mach Common.TY_u8)
                 | Ast.TY_str, Ast.TY_str -> ()
                 | _ ->
                     infer_lval src_ty dst;
diff --git a/src/comp/driver/rustc.rs b/src/comp/driver/rustc.rs
index 312166c4..f0ce9a95 100644
--- a/src/comp/driver/rustc.rs
+++ b/src/comp/driver/rustc.rs
@@ -203,8 +203,8 @@ impure fn main(vec[str] args) {
                 alt (output_file) {
                     case (none[str]) {
                         let vec[str] parts = _str.split(ifile, '.' as u8);
-                        parts = _vec.pop[str](parts);
-                        parts += ".bc";
+                        _vec.pop[str](parts);
+                        parts += vec(".bc");
                         auto ofile = _str.concat(parts);
                         compile_input(sess, env, ifile, ofile, shared,
                                       library_search_paths);
diff --git a/src/comp/front/eval.rs b/src/comp/front/eval.rs
index ac249848..4cf3765f 100644
--- a/src/comp/front/eval.rs
+++ b/src/comp/front/eval.rs
@@ -13,7 +13,6 @@ import front.parser.new_parser;
 import front.parser.parse_mod_items;
 import util.common;
 import util.common.filename;
-import util.common.append;
 import util.common.span;
 import util.common.new_str_hash;
 
@@ -394,7 +393,7 @@ impure fn eval_crate_directive(parser p,
             auto im = ast.item_mod(id, m0, next_id);
             auto i = @spanned(cdir.span, cdir.span, im);
             ast.index_item(index, i);
-            append[@ast.item](items, i);
+            _vec.push[@ast.item](items, i);
         }
 
         case (ast.cdir_dir_mod(?id, ?dir_opt, ?cdirs)) {
@@ -412,11 +411,11 @@ impure fn eval_crate_directive(parser p,
             auto im = ast.item_mod(id, m0, p.next_def_id());
             auto i = @spanned(cdir.span, cdir.span, im);
             ast.index_item(index, i);
-            append[@ast.item](items, i);
+            _vec.push[@ast.item](items, i);
         }
 
         case (ast.cdir_view_item(?vi)) {
-            append[@ast.view_item](view_items, vi);
+            _vec.push[@ast.view_item](view_items, vi);
             ast.index_view_item(index, vi);
         }
 
diff --git a/src/comp/front/extfmt.rs b/src/comp/front/extfmt.rs
index 255614d0..0a32a851 100644
--- a/src/comp/front/extfmt.rs
+++ b/src/comp/front/extfmt.rs
@@ -113,7 +113,7 @@ fn parse_fmt_string(str s) -> vec[piece] {
     fn flush_buf(str buf, &vec[piece] pieces) -> str {
         if (_str.byte_len(buf) > 0u) {
             auto piece = piece_string(buf);
-            pieces += piece;
+            pieces += vec(piece);
         }
         ret "";
     }
@@ -133,7 +133,7 @@ fn parse_fmt_string(str s) -> vec[piece] {
             } else {
                 buf = flush_buf(buf, pieces);
                 auto res = parse_conversion(s, i, lim);
-                pieces += res._0;
+                pieces += vec(res._0);
                 i = res._1;
             }
         } else {
diff --git a/src/comp/front/lexer.rs b/src/comp/front/lexer.rs
index 95fd32c7..403558e2 100644
--- a/src/comp/front/lexer.rs
+++ b/src/comp/front/lexer.rs
@@ -420,7 +420,7 @@ impure fn next_token(reader rdr) -> token.token {
 
     if (is_alpha(c) || c == '_') {
         while (is_alnum(c) || c == '_') {
-            accum_str += (c as u8);
+            _str.push_byte(accum_str, (c as u8));
             rdr.bump();
             c = rdr.curr();
         }
@@ -580,23 +580,23 @@ impure fn next_token(reader rdr) -> token.token {
                         alt (rdr.next()) {
                             case ('n') {
                                 rdr.bump();
-                                accum_str += '\n' as u8;
+                                _str.push_byte(accum_str, '\n' as u8);
                             }
                             case ('r') {
                                 rdr.bump();
-                                accum_str += '\r' as u8;
+                                _str.push_byte(accum_str, '\r' as u8);
                             }
                             case ('t') {
                                 rdr.bump();
-                                accum_str += '\t' as u8;
+                                _str.push_byte(accum_str, '\t' as u8);
                             }
                             case ('\\') {
                                 rdr.bump();
-                                accum_str += '\\' as u8;
+                                _str.push_byte(accum_str, '\\' as u8);
                             }
                             case ('"') {
                                 rdr.bump();
-                                accum_str += '"' as u8;
+                                _str.push_byte(accum_str, '"' as u8);
                             }
                             // FIXME: unicode numeric escapes.
                             case (?c2) {
@@ -607,7 +607,7 @@ impure fn next_token(reader rdr) -> token.token {
                         }
                     }
                     case (_) {
-                        accum_str += rdr.curr() as u8;
+                        _str.push_byte(accum_str, rdr.curr() as u8);
                     }
                 }
                 rdr.bump();
diff --git a/src/comp/front/parser.rs b/src/comp/front/parser.rs
index a5c79926..5e38345d 100644
--- a/src/comp/front/parser.rs
+++ b/src/comp/front/parser.rs
@@ -9,7 +9,6 @@ import std.map.hashmap;
 import driver.session;
 import util.common;
 import util.common.filename;
-import util.common.append;
 import util.common.span;
 import util.common.new_str_hash;
 
@@ -303,7 +302,7 @@ impure fn parse_constrs(parser p) -> common.spanned[vec[@ast.constr]] {
                 case (token.IDENT(_)) {
                     auto constr = parse_ty_constr(p);
                     hi = constr.span;
-                    append[@ast.constr](constrs, constr);
+                    _vec.push[@ast.constr](constrs, constr);
                     if (p.peek() == token.COMMA) {
                         p.bump();
                         more = false;
@@ -573,7 +572,7 @@ impure fn parse_path(parser p, greed g) -> ast.path {
         alt (p.peek()) {
             case (token.IDENT(?i)) {
                 hi = p.get_span();
-                ids += i;
+                ids += vec(i);
                 p.bump();
                 if (p.peek() == token.DOT) {
                     if (g == GREEDY) {
@@ -699,7 +698,7 @@ impure fn parse_bottom_expr(parser p) -> @ast.expr {
                     }
                     case (token.COMMA) {
                         p.bump();
-                        fields += parse_field(p);
+                        fields += vec(parse_field(p));
                     }
                     case (?t) {
                         unexpected(p, t);
@@ -877,7 +876,7 @@ impure fn extend_expr_by_ident(parser p, span lo, span hi,
         case (ast.expr_path(?pth, ?def, ?ann)) {
             if (_vec.len[@ast.ty](pth.node.types) == 0u) {
                 auto idents_ = pth.node.idents;
-                idents_ += i;
+                idents_ += vec(i);
                 auto tys = parse_ty_args(p, hi);
                 auto pth_ = spanned(pth.span, tys.span,
                                     rec(idents=idents_,
@@ -1763,8 +1762,8 @@ impure fn parse_item_obj(parser p, ast.layer lyr) -> @ast.item {
                 dtor = some[ast.block](parse_block(p));
             }
             case (_) {
-                append[@ast.method](meths,
-                                    parse_method(p));
+                _vec.push[@ast.method](meths,
+                                       parse_method(p));
             }
         }
     }
@@ -2161,12 +2160,11 @@ impure fn parse_rest_import_name(parser p, ast.ident first,
         -> @ast.view_item {
     auto lo = p.get_span();
     auto hi = lo;
-    let vec[ast.ident] identifiers = vec();
-    identifiers += first;
+    let vec[ast.ident] identifiers = vec(first);
     while (p.peek() != token.SEMI) {
         expect(p, token.DOT);
         auto i = parse_ident(p);
-        identifiers += i;
+        identifiers += vec(i);
     }
     p.bump();
     auto defined_id;
@@ -2402,7 +2400,7 @@ impure fn parse_crate_directives(parser p, token.token term)
 
     while (p.peek() != term) {
         auto cdir = @parse_crate_directive(p);
-        append[@ast.crate_directive](cdirs, cdir);
+        _vec.push[@ast.crate_directive](cdirs, cdir);
     }
 
     ret cdirs;
diff --git a/src/comp/front/token.rs b/src/comp/front/token.rs
index 8c594054..62c6406a 100644
--- a/src/comp/front/token.rs
+++ b/src/comp/front/token.rs
@@ -3,6 +3,7 @@ import util.common.ty_mach_to_str;
 import util.common.new_str_hash;
 import std._int;
 import std._uint;
+import std._str;
 
 tag binop {
     PLUS;
@@ -302,8 +303,8 @@ fn to_str(token t) -> str {
         case (LIT_CHAR(?c)) {
             // FIXME: escape and encode.
             auto tmp = "'";
-            tmp += c as u8;
-            tmp += '\'' as u8;
+            _str.push_byte(tmp, c as u8);
+            _str.push_byte(tmp, '\'' as u8);
             ret tmp;
         }
 
diff --git a/src/comp/middle/fold.rs b/src/comp/middle/fold.rs
index 73b2cab3..e2f2e192 100644
--- a/src/comp/middle/fold.rs
+++ b/src/comp/middle/fold.rs
@@ -7,7 +7,6 @@ import util.common.new_str_hash;
 import util.common.spanned;
 import util.common.span;
 import util.common.ty_mach;
-import util.common.append;
 
 import front.ast;
 import front.ast.fn_decl;
@@ -318,7 +317,7 @@ type ast_fold[ENV] =
 fn fold_path[ENV](&ENV env, ast_fold[ENV] fld, &path p) -> path {
     let vec[@ast.ty] tys_ = vec();
     for (@ast.ty t in p.node.types) {
-        append[@ast.ty](tys_, fold_ty(env, fld, t));
+        _vec.push[@ast.ty](tys_, fold_ty(env, fld, t));
     }
     let ast.path_ p_ = rec(idents=p.node.idents, types=tys_);
     ret fld.fold_path(env, p.span, p_);
@@ -357,7 +356,7 @@ fn fold_ty[ENV](&ENV env, ast_fold[ENV] fld, @ty t) -> @ty {
         case (ast.ty_tup(?elts)) {
             let vec[@ty] elts_ = vec();
             for (@ty elt in elts) {
-                append[@ty](elts_,fold_ty(env, fld, elt));
+                _vec.push[@ty](elts_,fold_ty(env, fld, elt));
             }
             ret fld.fold_ty_tup(env_, t.span, elts_);
         }
@@ -365,7 +364,7 @@ fn fold_ty[ENV](&ENV env, ast_fold[ENV] fld, @ty t) -> @ty {
         case (ast.ty_rec(?flds)) {
             let vec[ast.ty_field] flds_ = vec();
             for (ast.ty_field f in flds) {
-                append[ast.ty_field]
+                _vec.push[ast.ty_field]
                     (flds_, rec(ty=fold_ty(env, fld, f.ty) with f));
             }
             ret fld.fold_ty_rec(env_, t.span, flds_);
@@ -378,7 +377,7 @@ fn fold_ty[ENV](&ENV env, ast_fold[ENV] fld, @ty t) -> @ty {
                                       m.inputs, m.output);
                 alt (tfn.node) {
                     case (ast.ty_fn(?p, ?ins, ?out)) {
-                        append[ast.ty_method]
+                        _vec.push[ast.ty_method]
                             (meths_, rec(proto=p, inputs=ins, output=out
                                          with m));
                     }
@@ -494,7 +493,7 @@ fn fold_pat[ENV](&ENV env, ast_fold[ENV] fld, @ast.pat p) -> @ast.pat {
 fn fold_exprs[ENV](&ENV env, ast_fold[ENV] fld, vec[@expr] es) -> vec[@expr] {
     let vec[@expr] exprs = vec();
     for (@expr e in es) {
-        append[@expr](exprs, fold_expr(env, fld, e));
+        _vec.push[@expr](exprs, fold_expr(env, fld, e));
     }
     ret exprs;
 }
@@ -525,7 +524,7 @@ fn fold_expr[ENV](&ENV env, ast_fold[ENV] fld, &@expr e) -> @expr {
         case (ast.expr_tup(?es, ?t)) {
             let vec[ast.elt] elts = vec();
             for (ast.elt e in es) {
-                elts += fold_tup_elt[ENV](env, fld, e);
+                elts += vec(fold_tup_elt[ENV](env, fld, e));
             }
             ret fld.fold_expr_tup(env_, e.span, elts, t);
         }
@@ -534,7 +533,7 @@ fn fold_expr[ENV](&ENV env, ast_fold[ENV] fld, &@expr e) -> @expr {
             let vec[ast.field] fields = vec();
             let option.t[@expr] b = none[@expr];
             for (ast.field f in fs) {
-                fields += fold_rec_field(env, fld, f);
+                fields += vec(fold_rec_field(env, fld, f));
             }
             alt (base) {
                 case (none[@ast.expr]) { }
@@ -557,7 +556,7 @@ fn fold_expr[ENV](&ENV env, ast_fold[ENV] fld, &@expr e) -> @expr {
             for (option.t[@ast.expr] t_opt in args_opt) {
                 alt (t_opt) {
                     case (none[@ast.expr]) {
-                        aargs_opt += none[@ast.expr];
+                        aargs_opt += vec(none[@ast.expr]);
                     }
                     case (some[@ast.expr](?e)) {
                         aargs_opt += vec(some(fold_expr(env_, fld, e)));
@@ -779,7 +778,7 @@ fn fold_block[ENV](&ENV env, ast_fold[ENV] fld, &block blk) -> block {
     let vec[@ast.stmt] stmts = vec();
     for (@ast.stmt s in blk.node.stmts) {
         auto new_stmt = fold_stmt[ENV](env_, fld, s);
-        append[@ast.stmt](stmts, new_stmt);
+        _vec.push[@ast.stmt](stmts, new_stmt);
         ast.index_stmt(index, new_stmt);
     }
 
@@ -812,7 +811,7 @@ fn fold_fn_decl[ENV](&ENV env, ast_fold[ENV] fld,
                      &ast.fn_decl decl) -> ast.fn_decl {
     let vec[ast.arg] inputs = vec();
     for (ast.arg a in decl.inputs) {
-        inputs += fold_arg(env, fld, a);
+        inputs += vec(fold_arg(env, fld, a));
     }
     auto output = fold_ty[ENV](env, fld, decl.output);
     ret fld.fold_fn_decl(env, decl.effect, inputs, output);
@@ -846,7 +845,7 @@ fn fold_obj[ENV](&ENV env, ast_fold[ENV] fld, &ast._obj ob) -> ast._obj {
     let vec[ast.obj_field] fields = vec();
     let vec[@ast.method] meths = vec();
     for (ast.obj_field f in ob.fields) {
-        fields += fold_obj_field(env, fld, f);
+        fields += vec(fold_obj_field(env, fld, f));
     }
     let option.t[block] dtor = none[block];
     alt (ob.dtor) {
@@ -867,7 +866,7 @@ fn fold_obj[ENV](&ENV env, ast_fold[ENV] fld, &ast._obj ob) -> ast._obj {
                                                 m.node.ann),
                                span=m.span);
         let ENV _env = fld.update_env_for_item(env, i);
-        append[@ast.method](meths, fold_method(_env, fld, m));
+        _vec.push[@ast.method](meths, fold_method(_env, fld, m));
     }
     ret fld.fold_obj(env, fields, meths, dtor);
 }
@@ -944,8 +943,8 @@ fn fold_item[ENV](&ENV env, ast_fold[ENV] fld, @item i) -> @item {
                     auto new_ty = fold_ty[ENV](env_, fld, va.ty);
                     new_args += vec(rec(ty=new_ty, id=va.id));
                 }
-                new_variants += rec(name=v.name, args=new_args, id=v.id,
-                                    ann=v.ann);
+                new_variants += vec(rec(name=v.name, args=new_args, id=v.id,
+                                        ann=v.ann));
             }
             ret fld.fold_item_tag(env_, i.span, ident, new_variants,
                                   ty_params, id);
@@ -969,13 +968,13 @@ fn fold_mod[ENV](&ENV e, ast_fold[ENV] fld, &ast._mod m) -> ast._mod {
 
     for (@view_item vi in m.view_items) {
         auto new_vi = fold_view_item[ENV](e, fld, vi);
-        append[@view_item](view_items, new_vi);
+        _vec.push[@view_item](view_items, new_vi);
         ast.index_view_item(index, new_vi);
     }
 
     for (@item i in m.items) {
         auto new_item = fold_item[ENV](e, fld, i);
-        append[@item](items, new_item);
+        _vec.push[@item](items, new_item);
         ast.index_item(index, new_item);
     }
 
@@ -1009,12 +1008,12 @@ fn fold_native_mod[ENV](&ENV e, ast_fold[ENV] fld,
 
     for (@view_item vi in m.view_items) {
         auto new_vi = fold_view_item[ENV](e, fld, vi);
-        append[@view_item](view_items, new_vi);
+        _vec.push[@view_item](view_items, new_vi);
     }
 
     for (@native_item i in m.items) {
         auto new_item = fold_native_item[ENV](e, fld, i);
-        append[@native_item](items, new_item);
+        _vec.push[@native_item](items, new_item);
         ast.index_native_item(index, new_item);
     }
 
diff --git a/src/comp/middle/trans.rs b/src/comp/middle/trans.rs
index d0569afc..7bea575f 100644
--- a/src/comp/middle/trans.rs
+++ b/src/comp/middle/trans.rs
@@ -20,7 +20,6 @@ import middle.ty.pat_ty;
 import middle.ty.plain_ty;
 
 import util.common;
-import util.common.append;
 import util.common.istr;
 import util.common.new_def_hash;
 import util.common.new_str_hash;
@@ -476,7 +475,7 @@ fn type_of_explicit_args(@crate_ctxt cx,
     for (ty.arg arg in inputs) {
         if (ty.type_has_dynamic_size(arg.ty)) {
             check (arg.mode == ast.alias);
-            atys += T_typaram_ptr(cx.tn);
+            atys += vec(T_typaram_ptr(cx.tn));
         } else {
             let TypeRef t;
             alt (arg.mode) {
@@ -487,7 +486,7 @@ fn type_of_explicit_args(@crate_ctxt cx,
                     t = type_of_inner(cx, arg.ty, false);
                 }
             }
-            atys += t;
+            atys += vec(t);
         }
     }
     ret atys;
@@ -510,22 +509,22 @@ fn type_of_fn_full(@crate_ctxt cx,
 
     // Arg 0: Output pointer.
     if (ty.type_has_dynamic_size(output)) {
-        atys += T_typaram_ptr(cx.tn);
+        atys += vec(T_typaram_ptr(cx.tn));
     } else {
-        atys += T_ptr(type_of_inner(cx, output, false));
+        atys += vec(T_ptr(type_of_inner(cx, output, false)));
     }
 
     // Arg 1: Task pointer.
-    atys += T_taskptr(cx.tn);
+    atys += vec(T_taskptr(cx.tn));
 
     // Arg 2: Env (closure-bindings / self-obj)
     alt (obj_self) {
         case (some[TypeRef](?t)) {
             check (t as int != 0);
-            atys += t;
+            atys += vec(t);
         }
         case (_) {
-            atys += T_opaque_closure_ptr(cx.tn);
+            atys += vec(T_opaque_closure_ptr(cx.tn));
         }
     }
 
@@ -533,7 +532,7 @@ fn type_of_fn_full(@crate_ctxt cx,
     if (obj_self == none[TypeRef]) {
         auto i = 0u;
         while (i < ty_param_count) {
-            atys += T_ptr(T_tydesc(cx.tn));
+            atys += vec(T_ptr(T_tydesc(cx.tn)));
             i += 1u;
         }
     }
@@ -542,10 +541,11 @@ fn type_of_fn_full(@crate_ctxt cx,
         // If it's an iter, the 'output' type of the iter is actually the
         // *input* type of the function we're given as our iter-block
         // argument.
-        atys += T_fn_pair(cx.tn,
+        atys +=
+            vec(T_fn_pair(cx.tn,
                           type_of_fn_full(cx, ast.proto_fn, none[TypeRef],
                                           vec(rec(mode=ast.val, ty=output)),
-                                          plain_ty(ty.ty_nil), 0u));
+                                          plain_ty(ty.ty_nil), 0u)));
     }
 
     // ... then explicit args.
@@ -568,12 +568,12 @@ fn type_of_native_fn(@crate_ctxt cx, ast.native_abi abi,
                      @ty.t output) -> TypeRef {
     let vec[TypeRef] atys = vec();
     if (abi == ast.native_abi_rust) {
-        atys += T_taskptr(cx.tn);
+        atys += vec(T_taskptr(cx.tn));
         auto t = ty.ty_native_fn(abi, inputs, output);
         auto ty_param_count = ty.count_ty_params(plain_ty(t));
         auto i = 0u;
         while (i < ty_param_count) {
-            atys += T_ptr(T_tydesc(cx.tn));
+            atys += vec(T_ptr(T_tydesc(cx.tn)));
             i += 1u;
         }
     }
@@ -623,14 +623,14 @@ fn type_of_inner(@crate_ctxt cx, @ty.t t, bool boxed) -> TypeRef {
         case (ty.ty_tup(?elts)) {
             let vec[TypeRef] tys = vec();
             for (@ty.t elt in elts) {
-                tys += type_of_inner(cx, elt, boxed);
+                tys += vec(type_of_inner(cx, elt, boxed));
             }
             llty = T_struct(tys);
         }
         case (ty.ty_rec(?fields)) {
             let vec[TypeRef] tys = vec();
             for (ty.field f in fields) {
-                tys += type_of_inner(cx, f.ty, boxed);
+                tys += vec(type_of_inner(cx, f.ty, boxed));
             }
             llty = T_struct(tys);
         }
@@ -650,7 +650,7 @@ fn type_of_inner(@crate_ctxt cx, @ty.t t, bool boxed) -> TypeRef {
                     type_of_fn_full(cx, m.proto,
                                     some[TypeRef](self_ty),
                                     m.inputs, m.output, 0u);
-                mtys += T_ptr(mty);
+                mtys += vec(T_ptr(mty));
             }
             let TypeRef vtbl = T_struct(mtys);
             let TypeRef pair = T_struct(vec(T_ptr(vtbl),
@@ -870,10 +870,10 @@ fn trans_upcall2(builder b, @glue_fns glues, ValueRef lltaskptr,
 
     let ValueRef llglue = glues.upcall_glues.(n);
     let vec[ValueRef] call_args = vec(llupcall);
-    call_args += b.PtrToInt(lltaskptr, T_int());
+    call_args += vec( b.PtrToInt(lltaskptr, T_int()));
 
     for (ValueRef a in args) {
-        call_args += b.ZExtOrBitCast(a, T_int());
+        call_args += vec(b.ZExtOrBitCast(a, T_int()));
     }
 
     ret b.FastCall(llglue, call_args);
@@ -1112,7 +1112,7 @@ fn GEP_tup_like(@block_ctxt cx, @ty.t t,
     if (! ty.type_has_dynamic_size(t)) {
         let vec[ValueRef] v = vec();
         for (int i in ixs) {
-            v += C_int(i);
+            v += vec(C_int(i));
         }
         ret res(cx, cx.build.GEP(base, v));
     }
@@ -1159,8 +1159,8 @@ fn GEP_tup_like(@block_ctxt cx, @ty.t t,
         let vec[@ty.t] prefix = vec();
         let int i = 0;
         while (i < ix) {
-            append[@ty.t](prefix, ty.get_element_type(t, i as uint));
-            i +=1 ;
+            _vec.push[@ty.t](prefix, ty.get_element_type(t, i as uint));
+            i += 1 ;
         }
 
         auto selected = ty.get_element_type(t, i as uint);
@@ -1310,8 +1310,8 @@ fn linearize_ty_params(@block_ctxt cx, @ty.t t)
                         }
                     }
                     if (!seen) {
-                        r.vals += r.cx.fcx.lltydescs.get(pid);
-                        r.defs += pid;
+                        r.vals += vec(r.cx.fcx.lltydescs.get(pid));
+                        r.defs += vec(pid);
                     }
                 }
                 case (_) { }
@@ -2365,7 +2365,7 @@ fn trans_unary(@block_ctxt cx, ast.unop op,
             auto box_ty = node_ann_type(sub.bcx.fcx.ccx, a);
             sub = trans_malloc_boxed(sub.bcx, e_ty);
             find_scope_cx(cx).cleanups +=
-                clean(bind drop_ty(_, sub.val, box_ty));
+                vec(clean(bind drop_ty(_, sub.val, box_ty)));
 
             auto box = sub.val;
             auto rc = sub.bcx.build.GEP(box,
@@ -2646,7 +2646,8 @@ fn trans_vec_add(@block_ctxt cx, @ty.t t,
     r = copy_ty(r.bcx, INIT, tmp, lhs, t);
     auto bcx = trans_vec_append(r.bcx, t, tmp, rhs).bcx;
     tmp = load_scalar_or_boxed(bcx, tmp, t);
-    find_scope_cx(cx).cleanups += clean(bind drop_ty(_, tmp, t));
+    find_scope_cx(cx).cleanups +=
+        vec(clean(bind drop_ty(_, tmp, t)));
     ret res(bcx, tmp);
 }
 
@@ -2800,9 +2801,9 @@ fn join_results(@block_ctxt parent_cx,
 
     for (result r in ins) {
         if (! is_terminated(r.bcx)) {
-            live += r;
-            vals += r.val;
-            bbs += r.bcx.llbb;
+            live += vec(r);
+            vals += vec(r.val);
+            bbs += vec(r.bcx.llbb);
         }
     }
 
@@ -2875,7 +2876,8 @@ fn trans_for(@block_ctxt cx,
         cx.build.Br(scope_cx.llbb);
         auto local_res = alloc_local(scope_cx, local);
         auto bcx = copy_ty(local_res.bcx, INIT, local_res.val, curr, t).bcx;
-        scope_cx.cleanups += clean(bind drop_slot(_, local_res.val, t));
+        scope_cx.cleanups +=
+            vec(clean(bind drop_slot(_, local_res.val, t)));
         bcx = trans_block(bcx, body).bcx;
         bcx.build.Br(next_cx.llbb);
         ret res(next_cx, C_nil());
@@ -3245,7 +3247,8 @@ fn trans_pat_binding(@block_ctxt cx, @ast.pat pat, ValueRef llval)
 
             llvm.LLVMSetValueName(dst, _str.buf(id));
             bcx.fcx.lllocals.insert(def_id, dst);
-            bcx.cleanups += clean(bind drop_slot(_, dst, ty));
+            bcx.cleanups +=
+                vec(clean(bind drop_slot(_, dst, ty)));
 
             ret copy_ty(bcx, INIT, dst, llval, ty);
         }
@@ -3368,7 +3371,7 @@ fn lval_generic_fn(@block_ctxt cx,
         for (@ty.t t in tys) {
             auto td = get_tydesc(bcx, t);
             bcx = td.bcx;
-            append[ValueRef](tydescs, td.val);
+            _vec.push[ValueRef](tydescs, td.val);
         }
         auto gen = rec( item_type = tpt._1,
                         tydescs = tydescs );
@@ -3692,7 +3695,7 @@ fn trans_bind_thunk(@crate_ctxt cx,
                     val = bcx.build.PointerCast(val, llout_arg_ty);
                 }
 
-                llargs += val;
+                llargs += vec(val);
                 b += 1;
             }
 
@@ -3706,7 +3709,7 @@ fn trans_bind_thunk(@crate_ctxt cx,
                                                        llout_arg_ty);
                 }
 
-                llargs += passed_arg;
+                llargs += vec(passed_arg);
                 a += 1u;
             }
         }
@@ -3750,7 +3753,7 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
                 case (none[@ast.expr]) {
                 }
                 case (some[@ast.expr](?e)) {
-                    append[@ast.expr](bound, e);
+                    _vec.push[@ast.expr](bound, e);
                 }
             }
         }
@@ -3786,8 +3789,8 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
                 auto arg = trans_expr(bcx, e);
                 bcx = arg.bcx;
 
-                append[ValueRef](bound_vals, arg.val);
-                append[@ty.t](bound_tys, ty.expr_ty(e));
+                _vec.push[ValueRef](bound_vals, arg.val);
+                _vec.push[@ty.t](bound_tys, ty.expr_ty(e));
 
                 i += 1u;
             }
@@ -3914,7 +3917,7 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
                  pair_box);
 
             find_scope_cx(cx).cleanups +=
-                clean(bind drop_slot(_, pair_v, pair_ty));
+                vec(clean(bind drop_slot(_, pair_v, pair_ty)));
 
             ret res(bcx, pair_v);
         }
@@ -3959,23 +3962,24 @@ fn trans_args(@block_ctxt cx,
         }
     }
     if (ty.type_has_dynamic_size(retty)) {
-        llargs += bcx.build.PointerCast(llretslot,
-                                        T_typaram_ptr(cx.fcx.ccx.tn));
+        llargs += vec(bcx.build.PointerCast(llretslot,
+                                            T_typaram_ptr(cx.fcx.ccx.tn)));
     } else if (ty.count_ty_params(retty) != 0u) {
         // It's possible that the callee has some generic-ness somewhere in
         // its return value -- say a method signature within an obj or a fn
         // type deep in a structure -- which the caller has a concrete view
         // of. If so, cast the caller's view of the restlot to the callee's
         // view, for the sake of making a type-compatible call.
-        llargs += cx.build.PointerCast(llretslot,
-                                       T_ptr(type_of(bcx.fcx.ccx, retty)));
+        llargs +=
+            vec(cx.build.PointerCast(llretslot,
+                                     T_ptr(type_of(bcx.fcx.ccx, retty))));
     } else {
-        llargs += llretslot;
+        llargs += vec(llretslot);
     }
 
 
     // Arg 1: Task pointer.
-    llargs += bcx.fcx.lltaskptr;
+    llargs += vec(bcx.fcx.lltaskptr);
 
     // Arg 2: Env (closure-bindings / self-obj)
     alt (llobj) {
@@ -3983,10 +3987,10 @@ fn trans_args(@block_ctxt cx,
             // Every object is always found in memory,
             // and not-yet-loaded (as part of an lval x.y
             // doted method-call).
-            llargs += bcx.build.Load(ob);
+            llargs += vec(bcx.build.Load(ob));
         }
         case (_) {
-            llargs += llenv;
+            llargs += vec(llenv);
         }
     }
 
@@ -3997,7 +4001,7 @@ fn trans_args(@block_ctxt cx,
     alt (lliterbody) {
         case (none[ValueRef]) {}
         case (some[ValueRef](?lli)) {
-            llargs += lli;
+            llargs += vec(lli);
         }
     }
 
@@ -4054,7 +4058,7 @@ fn trans_args(@block_ctxt cx,
             val = bcx.build.PointerCast(val, lldestty);
         }
 
-        llargs += val;
+        llargs += vec(val);
         i += 1u;
     }
 
@@ -4116,7 +4120,8 @@ fn trans_call(@block_ctxt cx, @ast.expr f,
         // Retval doesn't correspond to anything really tangible in the frame,
         // but it's a ref all the same, so we put a note here to drop it when
         // we're done in this scope.
-        find_scope_cx(cx).cleanups += clean(bind drop_ty(_, retval, ret_ty));
+        find_scope_cx(cx).cleanups +=
+            vec(clean(bind drop_ty(_, retval, ret_ty)));
     }
 
     ret res(bcx, retval);
@@ -4130,7 +4135,8 @@ fn trans_tup(@block_ctxt cx, vec[ast.elt] elts,
     auto tup_val = tup_res.val;
     bcx = tup_res.bcx;
 
-    find_scope_cx(cx).cleanups += clean(bind drop_ty(_, tup_val, t));
+    find_scope_cx(cx).cleanups +=
+        vec(clean(bind drop_ty(_, tup_val, t)));
     let int i = 0;
 
     for (ast.elt e in elts) {
@@ -4171,7 +4177,8 @@ fn trans_vec(@block_ctxt cx, vec[@ast.expr] args,
 
     auto llty = type_of(bcx.fcx.ccx, t);
     auto vec_val = vi2p(bcx, sub.val, llty);
-    find_scope_cx(bcx).cleanups += clean(bind drop_ty(_, vec_val, t));
+    find_scope_cx(bcx).cleanups +=
+        vec(clean(bind drop_ty(_, vec_val, t)));
 
     auto body = bcx.build.GEP(vec_val, vec(C_int(0),
                                            C_int(abi.vec_elt_data)));
@@ -4226,7 +4233,8 @@ fn trans_rec(@block_ctxt cx, vec[ast.field] fields,
     auto rec_val = rec_res.val;
     bcx = rec_res.bcx;
 
-    find_scope_cx(cx).cleanups += clean(bind drop_ty(_, rec_val, t));
+    find_scope_cx(cx).cleanups +=
+        vec(clean(bind drop_ty(_, rec_val, t)));
     let int i = 0;
 
     auto base_val = C_nil();
@@ -4499,7 +4507,7 @@ fn trans_put(@block_ctxt cx, &option.t[@ast.expr] e) -> result {
                 llarg = bcx.build.Load(llarg);
             }
 
-            llargs += llarg;
+            llargs += vec(llarg);
         }
     }
 
@@ -4557,7 +4565,7 @@ fn init_local(@block_ctxt cx, @ast.local local) -> result {
     auto bcx = cx;
 
     find_scope_cx(cx).cleanups +=
-        clean(bind drop_slot(_, llptr, ty));
+        vec(clean(bind drop_slot(_, llptr, ty)));
 
     alt (local.init) {
         case (some[@ast.expr](?e)) {
@@ -5026,7 +5034,7 @@ fn trans_vtbl(@crate_ctxt cx, TypeRef self_ty,
 
         trans_fn(mcx, m.node.meth, m.node.id, some[TypeRef](self_ty),
                  ty_params, m.node.ann);
-        methods += llfn;
+        methods += vec(llfn);
     }
     auto vtbl = C_struct(methods);
     auto gvar = llvm.LLVMAddGlobal(cx.llmod,
@@ -5085,14 +5093,14 @@ fn trans_obj(@crate_ctxt cx, &ast._obj ob, ast.def_id oid,
         // Malloc a box for the body and copy args in.
         let vec[@ty.t] obj_fields = vec();
         for (ty.arg a in arg_tys) {
-            append[@ty.t](obj_fields, a.ty);
+            _vec.push[@ty.t](obj_fields, a.ty);
         }
 
         // Synthesize an obj body type.
         auto tydesc_ty = plain_ty(ty.ty_type);
         let vec[@ty.t] tps = vec();
         for (ast.ty_param tp in ty_params) {
-            append[@ty.t](tps, tydesc_ty);
+            _vec.push[@ty.t](tps, tydesc_ty);
         }
 
         let @ty.t typarams_ty = plain_ty(ty.ty_tup(tps));
diff --git a/src/comp/middle/ty.rs b/src/comp/middle/ty.rs
index 0c540f5c..923d97ff 100644
--- a/src/comp/middle/ty.rs
+++ b/src/comp/middle/ty.rs
@@ -11,7 +11,6 @@ import driver.session;
 import front.ast;
 import front.ast.mutability;
 import util.common;
-import util.common.append;
 import util.common.new_def_hash;
 import util.common.span;
 
@@ -756,7 +755,7 @@ fn field_num(session.session sess, &span sp, &ast.ident id) -> uint {
                 accum += (c as uint) - ('0' as uint);
             } else {
                 auto s = "";
-                s += c;
+                s += _str.unsafe_from_byte(c);
                 sess.span_err(sp,
                               "bad numeric field on tuple: "
                               + " non-digit character: "
@@ -1104,7 +1103,7 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
 
                             alt (result) {
                                 case (ures_ok(?rty)) {
-                                    append[@ty.t](result_tps, rty);
+                                    _vec.push[@ty.t](result_tps, rty);
                                 }
                                 case (_) {
                                     ret result;
@@ -1244,7 +1243,7 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
                                                      handler);
                             alt (result) {
                                 case (ures_ok(?rty)) {
-                                    append[@ty.t](result_elems,rty);
+                                    _vec.push[@ty.t](result_elems,rty);
                                 }
                                 case (_) {
                                     ret result;
@@ -1301,7 +1300,7 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
                                                      handler);
                             alt (result) {
                                 case (ures_ok(?rty)) {
-                                    append[field]
+                                    _vec.push[field]
                                         (result_fields,
                                          rec(ty=rty with expected_field));
                                 }
diff --git a/src/comp/middle/typeck.rs b/src/comp/middle/typeck.rs
index 1818c4fd..6668c208 100644
--- a/src/comp/middle/typeck.rs
+++ b/src/comp/middle/typeck.rs
@@ -4,7 +4,6 @@ import front.ast.mutability;
 import middle.fold;
 import driver.session;
 import util.common;
-import util.common.append;
 import util.common.span;
 
 import middle.ty;
@@ -320,14 +319,14 @@ fn ast_ty_to_ty(ty_getter getter, &@ast.ty ast_ty) -> @ty.t {
         case (ast.ty_tup(?fields)) {
             let vec[@ty.t] flds = vec();
             for (@ast.ty field in fields) {
-                append[@ty.t](flds, ast_ty_to_ty(getter, field));
+                _vec.push[@ty.t](flds, ast_ty_to_ty(getter, field));
             }
             sty = ty.ty_tup(flds);
         }
         case (ast.ty_rec(?fields)) {
             let vec[field] flds = vec();
             for (ast.ty_field f in fields) {
-                append[field](flds, rec(ident=f.ident,
+                _vec.push[field](flds, rec(ident=f.ident,
                                         ty=ast_ty_to_ty(getter, f.ty)));
             }
             sty = ty.ty_rec(flds);
@@ -371,7 +370,7 @@ fn ast_ty_to_ty(ty_getter getter, &@ast.ty ast_ty) -> @ty.t {
             for (ast.ty_method m in meths) {
                 auto ins = _vec.map[ast.ty_arg, arg](f, m.inputs);
                 auto out = ast_ty_to_ty(getter, m.output);
-                append[ty.method](tmeths,
+                _vec.push[ty.method](tmeths,
                                   rec(proto=m.proto,
                                       ident=m.ident,
                                       inputs=ins,
@@ -565,7 +564,7 @@ fn collect_item_types(session.session sess, @ast.crate crate)
         for (ast.obj_field f in obj_info.fields) {
             auto g = bind getter(id_to_ty_item, item_to_ty, _);
             auto t_field = ast_ty_to_ty(g, f.ty);
-            append[arg](t_inputs, rec(mode=ast.alias, ty=t_field));
+            _vec.push[arg](t_inputs, rec(mode=ast.alias, ty=t_field));
         }
         auto t_fn = plain_ty(ty.ty_fn(ast.proto_fn, t_inputs, t_obj));
         ret t_fn;
@@ -870,7 +869,7 @@ fn collect_item_types(session.session sess, @ast.crate crate)
                 with meth.node
             );
             m = @rec(node=m_ with *meth);
-            append[@ast.method](methods, m);
+            _vec.push[@ast.method](methods, m);
         }
         auto g = bind getter(e.id_to_ty_item, e.item_to_ty, _);
         for (ast.obj_field fld in ob.fields) {
@@ -879,7 +878,7 @@ fn collect_item_types(session.session sess, @ast.crate crate)
                 ann=ast.ann_type(fty, none[vec[@ty.t]])
                 with fld
             );
-            append[ast.obj_field](fields, f);
+            _vec.push[ast.obj_field](fields, f);
         }
 
         auto ob_ = rec(methods = methods,
@@ -1572,14 +1571,14 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
 
                     // FIXME: this breaks aliases. We need a ty_fn_arg.
                     auto arg_ty = rec(mode=ast.val, ty=expr_ty(a_0));
-                    append[arg](arg_tys_0, arg_ty);
+                    _vec.push[arg](arg_tys_0, arg_ty);
                 }
                 case (none[@ast.expr]) {
                     args_0 += vec(none[@ast.expr]);
 
                     // FIXME: breaks aliases too?
                     auto typ = next_ty_var(fcx.ccx);
-                    append[arg](arg_tys_0, rec(mode=ast.val, ty=typ));
+                    _vec.push[arg](arg_tys_0, rec(mode=ast.val, ty=typ));
                 }
             }
         }
@@ -1623,10 +1622,11 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                 case (some[@ast.expr](?e_0)) {
                     auto arg_ty_1 = arg_tys_1.(i);
                     auto e_1 = demand_expr(fcx, arg_ty_1.ty, e_0);
-                    append[option.t[@ast.expr]](args_1, some[@ast.expr](e_1));
+                    _vec.push[option.t[@ast.expr]](args_1,
+                                                   some[@ast.expr](e_1));
                 }
                 case (none[@ast.expr]) {
-                    append[option.t[@ast.expr]](args_1, none[@ast.expr]);
+                    _vec.push[option.t[@ast.expr]](args_1, none[@ast.expr]);
                 }
             }
 
@@ -2114,7 +2114,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                 auto expr_1 = check_expr(fcx, e);
                 auto expr_t = expr_ty(expr_1);
                 demand(fcx, expr.span, t, expr_t);
-                append[@ast.expr](args_1,expr_1);
+                _vec.push[@ast.expr](args_1,expr_1);
             }
             auto ann = ast.ann_type(plain_ty(ty.ty_vec(t)), none[vec[@ty.t]]);
             ret @fold.respan[ast.expr_](expr.span,
@@ -2131,8 +2131,8 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                 if (e.mut == ast.mut) {
                     expr_t = @rec(mut=ast.mut with *expr_t);
                 }
-                append[ast.elt](elts_1, rec(expr=expr_1 with e));
-                append[@ty.t](elts_t, expr_t);
+                _vec.push[ast.elt](elts_1, rec(expr=expr_1 with e));
+                _vec.push[@ty.t](elts_t, expr_t);
             }
 
             auto ann = ast.ann_type(plain_ty(ty.ty_tup(elts_t)),
@@ -2160,8 +2160,8 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                 if (f.mut == ast.mut) {
                     expr_t = @rec(mut=ast.mut with *expr_t);
                 }
-                append[ast.field](fields_1, rec(expr=expr_1 with f));
-                append[field](fields_t, rec(ident=f.ident, ty=expr_t));
+                _vec.push[ast.field](fields_1, rec(expr=expr_1 with f));
+                _vec.push[field](fields_t, rec(ident=f.ident, ty=expr_t));
             }
 
             auto ann = ast.ann_none;
@@ -2418,7 +2418,7 @@ fn check_stmt(&@fn_ctxt fcx, &@ast.stmt stmt) -> @ast.stmt {
 fn check_block(&@fn_ctxt fcx, &ast.block block) -> ast.block {
     let vec[@ast.stmt] stmts = vec();
     for (@ast.stmt s in block.node.stmts) {
-        append[@ast.stmt](stmts, check_stmt(fcx, s));
+        _vec.push[@ast.stmt](stmts, check_stmt(fcx, s));
     }
 
     auto expr = none[@ast.expr];
diff --git a/src/comp/pretty/pp.rs b/src/comp/pretty/pp.rs
index d3145180..0c355001 100644
--- a/src/comp/pretty/pp.rs
+++ b/src/comp/pretty/pp.rs
@@ -39,12 +39,12 @@ fn mkstate(io.writer out, uint width) -> ps {
 
 impure fn push_context(ps p, contexttype tp, uint indent) {
   before_print(p, false);
-  p.context = _vec.push[context](p.context, rec(tp=tp, indent=base_indent(p)
-                                                + indent));
+  _vec.push[context](p.context, rec(tp=tp, indent=base_indent(p)
+                                    + indent));
 }
 
-impure fn pop_context(ps p) {
-  p.context = _vec.pop[context](p.context);
+fn pop_context(ps p) {
+  _vec.pop[context](p.context);
 }
 
 impure fn add_token(ps p, token tok) {
@@ -110,7 +110,8 @@ impure fn finish_block_scan(ps p, contexttype tp) {
   }
   p.scandepth = 0u;
   push_context(p, tp, indent);
-  for (token t in _vec.shift[token](p.buffered)) {add_token(p, t);}
+  _vec.shift[token](p.buffered);
+  for (token t in p.buffered) { add_token(p, t); }
 }
 
 impure fn finish_break_scan(ps p) {
@@ -125,7 +126,8 @@ impure fn finish_break_scan(ps p) {
     p.col += width;
   }
   p.scandepth = 0u;
-  for (token t in _vec.shift[token](p.buffered)) {add_token(p, t);}
+  _vec.shift[token](p.buffered);
+  for (token t in p.buffered) { add_token(p, t); }
 }
 
 impure fn start_scan(ps p, token tok) {
diff --git a/src/comp/pretty/pprust.rs b/src/comp/pretty/pprust.rs
index a25bc447..1f9b455b 100644
--- a/src/comp/pretty/pprust.rs
+++ b/src/comp/pretty/pprust.rs
@@ -717,7 +717,7 @@ fn escape_str(str st, char to_escape) -> str {
       case ('\\') {out += "\\\\";}
       case (?cur) {
         if (cur == to_escape) {out += "\\";}
-        out += cur as u8;
+        _str.push_byte(out, cur as u8);
       }
     }
     i += 1u;
diff --git a/src/comp/util/common.rs b/src/comp/util/common.rs
index 63ec2c69..4b4f5481 100644
--- a/src/comp/util/common.rs
+++ b/src/comp/util/common.rs
@@ -68,15 +68,6 @@ fn istr(int i) -> str {
     ret _int.to_str(i, 10u);
 }
 
-
-// FIXME: Weird bug. Due to the way we auto-deref + in +=, we can't append a
-// boxed value to a vector-of-boxes using +=.  Best to figure out a way to fix
-// this. Deref-on-demand or something? It's a hazard of the ambiguity between
-// single-element and vector append.
-fn append[T](&mutable vec[T] v, &T t) {
-    v += t;
-}
-
 //
 // Local Variables:
 // mode: rust
diff --git a/src/lib/_str.rs b/src/lib/_str.rs
index 526dac8f..db9413b9 100644
--- a/src/lib/_str.rs
+++ b/src/lib/_str.rs
@@ -111,6 +111,11 @@ fn unsafe_from_bytes(vec[u8] v) -> str {
     ret rustrt.str_from_vec(v);
 }
 
+fn unsafe_from_byte(u8 u) -> str {
+    ret rustrt.str_from_vec(vec(u));
+}
+
+
 fn refcount(str s) -> uint {
     auto r = rustrt.refcount[u8](s);
     if (r == dbg.const_refcount) {
@@ -190,7 +195,6 @@ fn starts_with(str haystack, str needle) -> bool {
     ret eq(substr(haystack, 0u, needle_len), needle);
 }
 
-
 fn ends_with(str haystack, str needle) -> bool {
     let uint haystack_len = byte_len(haystack);
     let uint needle_len = byte_len(needle);
@@ -206,34 +210,60 @@ fn ends_with(str haystack, str needle) -> bool {
            needle);
 }
 
-
 fn substr(str s, uint begin, uint len) -> str {
     let str accum = "";
     let uint i = begin;
     while (i < begin+len) {
-        accum += s.(i);
+        accum += unsafe_from_byte(s.(i));
         i += 1u;
     }
     ret accum;
 }
 
+fn shift_byte(&mutable str s) -> u8 {
+    auto len = byte_len(s);
+    check(len > 0u);
+    auto b = s.(0);
+    s = substr(s, 1u, len - 1u);
+    ret b;
+}
+
+fn pop_byte(&mutable str s) -> u8 {
+    auto len = byte_len(s);
+    check(len > 0u);
+    auto b = s.(len - 1u);
+    s = substr(s, 0u, len - 1u);
+    ret b;
+}
+
+fn push_byte(&mutable str s, u8 b) {
+    s += unsafe_from_byte(b);
+}
+
+fn unshift_byte(&mutable str s, u8 b) {
+    auto res = alloc(byte_len(s) + 1u);
+    res += unsafe_from_byte(b);
+    res += s;
+    s = res;
+}
+
 fn split(str s, u8 sep) -> vec[str] {
     let vec[str] v = vec();
     let str accum = "";
     let bool ends_with_sep = false;
     for (u8 c in s) {
         if (c == sep) {
-            v += accum;
+            v += vec(accum);
             accum = "";
             ends_with_sep = true;
         } else {
-            accum += c;
+            accum += unsafe_from_byte(c);
             ends_with_sep = false;
         }
     }
     if (_str.byte_len(accum) != 0u ||
         ends_with_sep) {
-        v += accum;
+        v += vec(accum);
     }
     ret v;
 }
diff --git a/src/lib/_uint.rs b/src/lib/_uint.rs
index ceee9c77..5e8d4b97 100644
--- a/src/lib/_uint.rs
+++ b/src/lib/_uint.rs
@@ -61,7 +61,7 @@ fn to_str(mutable uint n, uint radix) -> str
 
     let str s = "";
     while (n != 0u) {
-        s += digit(n % radix) as u8;
+        s += _str.unsafe_from_byte(digit(n % radix) as u8);
         n /= radix;
     }
 
@@ -69,7 +69,7 @@ fn to_str(mutable uint n, uint radix) -> str
     let uint len = _str.byte_len(s);
     while (len != 0u) {
         len -= 1u;
-        s1 += s.(len);
+        s1 += _str.unsafe_from_byte(s.(len));
     }
     ret s1;
 
diff --git a/src/lib/_vec.rs b/src/lib/_vec.rs
index 680c8884..80cd242d 100644
--- a/src/lib/_vec.rs
+++ b/src/lib/_vec.rs
@@ -103,28 +103,32 @@ fn slice[T](vec[T] v, uint start, uint end) -> vec[T] {
     ret result;
 }
 
-fn shift[T](vec[T] v) -> vec[T] {
-    check(len[T](v) > 0u);
-    ret slice[T](v, 1u, len[T](v));
+fn shift[T](&mutable vec[T] v) -> T {
+    auto ln = len[T](v);
+    check(ln > 0u);
+    auto e = v.(0);
+    v = slice[T](v, 1u, ln);
+    ret e;
 }
 
-fn pop[T](vec[T] v) -> vec[T] {
-    check(len[T](v) > 0u);
-    ret slice[T](v, 0u, len[T](v) - 1u);
+fn pop[T](&mutable vec[T] v) -> T {
+    auto ln = len[T](v);
+    check(ln > 0u);
+    ln -= 1u;
+    auto e = v.(ln);
+    v = slice[T](v, 0u, ln);
+    ret e;
 }
 
-fn push[T](vec[T] v, &T t) -> vec[T] {
-    v += t;
-    ret v;
+fn push[T](&mutable vec[T] v, &T t) {
+    v += vec(t);
 }
 
-fn unshift[T](vec[T] v, &T t) -> vec[T] {
+fn unshift[T](&mutable vec[T] v, &T t) {
     auto res = alloc[T](len[T](v) + 1u);
-    res += t;
-    for (T t_ in v) {
-        res += t_;
-    }
-    ret res;
+    res += vec(t);
+    res += v;
+    v = res;
 }
 
 fn grow[T](&mutable vec[T] v, int n, &T initval) {
@@ -152,7 +156,7 @@ fn map2[T,U,V](&operator2[T,U,V] f, &vec[T] v0, &vec[U] v1) -> vec[V] {
     let vec[V] u = alloc[V](v0_len);
     auto i = 0u;
     while (i < v0_len) {
-        u += f(v0.(i), v1.(i));
+        u += vec(f(v0.(i), v1.(i)));
         i += 1u;
     }
 
diff --git a/src/lib/fs.rs b/src/lib/fs.rs
index 1b9ed4b0..677bbcc4 100644
--- a/src/lib/fs.rs
+++ b/src/lib/fs.rs
@@ -38,8 +38,18 @@ impure fn list_dir(path p) -> vec[str] {
   let vec[str] full_paths = vec();
   for (str filename in os_fs.list_dir(p)) {
     if (!_str.eq(filename, ".")) {if (!_str.eq(filename, "..")) {
-      full_paths = _vec.push[str](full_paths, p + filename);
+      _vec.push[str](full_paths, p + filename);
     }}
   }
   ret full_paths;
 }
+
+
+// Local Variables:
+// mode: rust;
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// compile-command: "make -k -C .. 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
+// End:
diff --git a/src/lib/posix_fs.rs b/src/lib/posix_fs.rs
index 05366a15..676d4150 100644
--- a/src/lib/posix_fs.rs
+++ b/src/lib/posix_fs.rs
@@ -10,10 +10,19 @@ impure fn list_dir(str path) -> vec[str] {
   while (true) {
     auto ent = os.libc.readdir(dir);
     if (ent as int == 0) {break;}
-    result = _vec.push[str](result, rustrt.rust_dirent_filename(ent));
+    _vec.push[str](result, rustrt.rust_dirent_filename(ent));
   }
   os.libc.closedir(dir);
   ret result;
 }
 
 const char path_sep = '/';
+
+// Local Variables:
+// mode: rust;
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// compile-command: "make -k -C .. 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
+// End:
diff --git a/src/lib/run_program.rs b/src/lib/run_program.rs
index bd9edbc8..f3ea95a1 100644
--- a/src/lib/run_program.rs
+++ b/src/lib/run_program.rs
@@ -8,9 +8,9 @@ native "rust" mod rustrt {
 fn argvec(str prog, vec[str] args) -> vec[sbuf] {
     auto argptrs = vec(_str.buf(prog));
     for (str arg in args) {
-        argptrs = _vec.push[sbuf](argptrs, _str.buf(arg));
+        _vec.push[sbuf](argptrs, _str.buf(arg));
     }
-    argptrs = _vec.push[sbuf](argptrs, 0 as sbuf);
+    _vec.push[sbuf](argptrs, 0 as sbuf);
     ret argptrs;
 }
 
diff --git a/src/lib/sha1.rs b/src/lib/sha1.rs
index a57ea894..6b4e623b 100644
--- a/src/lib/sha1.rs
+++ b/src/lib/sha1.rs
@@ -169,10 +169,11 @@ fn mk_sha1() -> sha1 {
 
         let vec[u8] res = vec();
         for (u32 hpart in st.h) {
-            res += (hpart >> 24u32) & 0xFFu32 as u8;
-            res += (hpart >> 16u32) & 0xFFu32 as u8;
-            res += (hpart >> 8u32) & 0xFFu32 as u8;
-            res += hpart & 0xFFu32 as u8;
+            auto a = (hpart >> 24u32) & 0xFFu32 as u8;
+            auto b = (hpart >> 16u32) & 0xFFu32 as u8;
+            auto c = (hpart >> 8u32) & 0xFFu32 as u8;
+            auto d = (hpart & 0xFFu32 as u8);
+            res += vec(a,b,c,d);
         }
         ret res;
     }
diff --git a/src/lib/sort.rs b/src/lib/sort.rs
index cff7efce..52839b1f 100644
--- a/src/lib/sort.rs
+++ b/src/lib/sort.rs
@@ -5,38 +5,38 @@ type lteq[T] = fn(&T a, &T b) -> bool;
 
 fn merge_sort[T](lteq[T] le, vec[T] v) -> vec[T] {
 
-  fn merge[T](lteq[T] le, vec[T] a, vec[T] b) -> vec[T] {
-    let vec[T] res = vec();
-    let uint a_len = len[T](a);
-    let uint a_ix = 0u;
-    let uint b_len = len[T](b);
-    let uint b_ix = 0u;
-    while (a_ix < a_len && b_ix < b_len) {
-      if (le(a.(a_ix), b.(b_ix))) {
-        res += a.(a_ix);
-        a_ix += 1u;
-      } else {
-        res += b.(b_ix);
-        b_ix += 1u;
-      }
+    fn merge[T](lteq[T] le, vec[T] a, vec[T] b) -> vec[T] {
+        let vec[T] res = vec();
+        let uint a_len = len[T](a);
+        let uint a_ix = 0u;
+        let uint b_len = len[T](b);
+        let uint b_ix = 0u;
+        while (a_ix < a_len && b_ix < b_len) {
+            if (le(a.(a_ix), b.(b_ix))) {
+                res += vec(a.(a_ix));
+                a_ix += 1u;
+            } else {
+                res += vec(b.(b_ix));
+                b_ix += 1u;
+            }
+        }
+        res += slice[T](a, a_ix, a_len);
+        res += slice[T](b, b_ix, b_len);
+        ret res;
     }
-    res += slice[T](a, a_ix, a_len);
-    res += slice[T](b, b_ix, b_len);
-    ret res;
-  }
 
-  let uint v_len = len[T](v);
+    let uint v_len = len[T](v);
 
-  if (v_len <= 1u) {
-    ret v;
-  }
+    if (v_len <= 1u) {
+        ret v;
+    }
 
-  let uint mid = v_len / 2u;
-  let vec[T] a = slice[T](v, 0u, mid);
-  let vec[T] b = slice[T](v, mid, v_len);
-  ret merge[T](le,
-               merge_sort[T](le, a),
-               merge_sort[T](le, b));
+    let uint mid = v_len / 2u;
+    let vec[T] a = slice[T](v, 0u, mid);
+    let vec[T] b = slice[T](v, mid, v_len);
+    ret merge[T](le,
+                 merge_sort[T](le, a),
+                 merge_sort[T](le, b));
 }
 
 // Local Variables:
diff --git a/src/lib/std.rc b/src/lib/std.rc
index a339fd85..7a3cdbb2 100644
--- a/src/lib/std.rc
+++ b/src/lib/std.rc
@@ -34,6 +34,17 @@ auth _str = unsafe;
 auth _vec = unsafe;
 auth _task = unsafe;
 
+
+// FIXME: impure on these will infect caller in a way that is totally
+// beyond reason, if the caller's mutated-argument doesn't escape;
+// 'impure' needs work.
+auth _str.unshift_byte = impure;
+auth _str.shift_byte = impure;
+auth _str.pop_byte = impure;
+auth _vec.shift = impure;
+auth _vec.unshift = impure;
+auth _vec.pop = impure;
+
 auth dbg = unsafe;
 
 auth _uint.next_power_of_two = unsafe;
diff --git a/src/lib/win32_fs.rs b/src/lib/win32_fs.rs
index 641ef33e..f88d7798 100644
--- a/src/lib/win32_fs.rs
+++ b/src/lib/win32_fs.rs
@@ -8,3 +8,12 @@ impure fn list_dir(str path) -> vec[str] {
 }
 
 const char path_sep = '\\';
+
+// Local Variables:
+// mode: rust;
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// compile-command: "make -k -C .. 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
+// End:
diff --git a/src/test/bench/99-bottles/99bob-iter.rs b/src/test/bench/99-bottles/99bob-iter.rs
index 336939c8..09638941 100644
--- a/src/test/bench/99-bottles/99bob-iter.rs
+++ b/src/test/bench/99-bottles/99bob-iter.rs
@@ -40,7 +40,7 @@ case (1) {
       b += ns;
     }
     else {
-      b += t.(i);
+      _str.push_byte(b, t.(i));
     }
     i += 1u;
   }
diff --git a/src/test/bench/99-bottles/99bob-simple.rs b/src/test/bench/99-bottles/99bob-simple.rs
index 10fec27a..3c426f51 100644
--- a/src/test/bench/99-bottles/99bob-simple.rs
+++ b/src/test/bench/99-bottles/99bob-simple.rs
@@ -39,7 +39,7 @@ case (1) {
       b += ns;
     }
     else {
-      b += t.(i);
+      _str.push_byte(b, t.(i));
     }
     i += 1u;
   }
diff --git a/src/test/bench/shootout/fasta.rs b/src/test/bench/shootout/fasta.rs
index ffec6db9..f88f4330 100644
--- a/src/test/bench/shootout/fasta.rs
+++ b/src/test/bench/shootout/fasta.rs
@@ -28,7 +28,7 @@ fn make_cumulative(vec[aminoacids] aa) -> vec[aminoacids] {
   let vec[aminoacids] ans = vec();
   for (aminoacids a in aa) {
     cp += a._1;
-    ans += tup(a._0, cp);
+    ans += vec(tup(a._0, cp));
   }
   ret ans;
 }
@@ -59,7 +59,7 @@ fn make_random_fasta(str id, str desc, vec[aminoacids] genelist, int n) {
   auto rng = myrandom(std.rand.mk_rng().next());
   let str op = "";
   for each (uint i in _uint.range(0u, n as uint)) {
-    op += select_random(rng.next(100u32), genelist) as u8;
+    _str.push_byte(op, select_random(rng.next(100u32), genelist) as u8);
     if (_str.byte_len(op) >= LINE_LENGTH()) {
       log(op);
       op = "";
@@ -76,7 +76,7 @@ fn make_repeat_fasta(str id, str desc, str s, int n) {
   let uint sl = _str.byte_len(s);
   for each (uint i in _uint.range(0u, n as uint)) {
 
-    op += s.(i % sl);
+    _str.push_byte(op, s.(i % sl));
     if (_str.byte_len(op) >= LINE_LENGTH()) {
       log(op);
       op = "";
diff --git a/src/test/run-pass/append-units.rs b/src/test/run-pass/append-units.rs
deleted file mode 100644
index 05b3478b..00000000
--- a/src/test/run-pass/append-units.rs
+++ /dev/null
@@ -1,15 +0,0 @@
-fn main() {
-  auto v = vec(1,2,3);
-  v += 4;
-  v += 5;
-  check (v.(3) == 4);
-  check (v.(4) == 5);
-
-  auto s = "hello";
-  log s;
-  s += 'z' as u8;
-  s += 'y' as u8;
-  log s;
-  check (s.(5) == 'z' as u8);
-  check (s.(6) == 'y' as u8);
-}