Merge branch 'polyfox-module-prepend'

8 files changed, 493 insertions, 51 deletions

diff --git a/include/mruby.h b/include/mruby.h
index 1b792ce90..b4ec13fdc 100644
--- a/include/mruby.h
+++ b/include/mruby.h
@@ -206,6 +206,7 @@ MRB_API struct RClass *mrb_define_class(mrb_state *, const char*, struct RClass*
 MRB_API struct RClass *mrb_define_module(mrb_state *, const char*);
 MRB_API mrb_value mrb_singleton_class(mrb_state*, mrb_value);
 MRB_API void mrb_include_module(mrb_state*, struct RClass*, struct RClass*);
+MRB_API void mrb_prepend_module(mrb_state*, struct RClass*, struct RClass*);
 
 MRB_API void mrb_define_method(mrb_state*, struct RClass*, const char*, mrb_func_t, mrb_aspec);
 MRB_API void mrb_define_class_method(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec);
diff --git a/include/mruby/class.h b/include/mruby/class.h
index 9d5260a24..85f3e12c6 100644
--- a/include/mruby/class.h
+++ b/include/mruby/class.h
@@ -48,8 +48,20 @@ mrb_class(mrb_state *mrb, mrb_value v)
   }
 }
 
-#define MRB_SET_INSTANCE_TT(c, tt) c->flags = ((c->flags & ~0xff) | (char)tt)
-#define MRB_INSTANCE_TT(c) (enum mrb_vtype)(c->flags & 0xff)
+// TODO: figure out where to put user flags
+#define MRB_FLAG_IS_PREPENDED (1 << 19)
+#define MRB_FLAG_IS_ORIGIN (1 << 20)
+#define MRB_CLASS_ORIGIN(c) do {\
+  if (c->flags & MRB_FLAG_IS_PREPENDED) {\
+    c = c->super;\
+    while (!(c->flags & MRB_FLAG_IS_ORIGIN)) {\
+      c = c->super;\
+    }\
+  }\
+} while (0)
+#define MRB_INSTANCE_TT_MASK (0xFF)
+#define MRB_SET_INSTANCE_TT(c, tt) c->flags = ((c->flags & ~MRB_INSTANCE_TT_MASK) | (char)tt)
+#define MRB_INSTANCE_TT(c) (enum mrb_vtype)(c->flags & MRB_INSTANCE_TT_MASK)
 
 MRB_API struct RClass* mrb_define_class_id(mrb_state*, mrb_sym, struct RClass*);
 MRB_API struct RClass* mrb_define_module_id(mrb_state*, mrb_sym);
diff --git a/include/mruby/object.h b/include/mruby/object.h
index fe55620fe..6633a23e8 100644
--- a/include/mruby/object.h
+++ b/include/mruby/object.h
@@ -14,6 +14,8 @@
   struct RClass *c;\
   struct RBasic *gcnext
 
+#define MRB_FLAG_TEST(obj, flag) ((obj)->flags & flag)
+
 /* white: 011, black: 100, gray: 000 */
 #define MRB_GC_GRAY 0
 #define MRB_GC_WHITE_A 1
diff --git a/src/class.c b/src/class.c
index 33fb61211..c3c3e0b8f 100644
--- a/src/class.c
+++ b/src/class.c
@@ -76,7 +76,7 @@ prepare_singleton_class(mrb_state *mrb, struct RBasic *o)
 
   if (o->c->tt == MRB_TT_SCLASS) return;
   sc = (struct RClass*)mrb_obj_alloc(mrb, MRB_TT_SCLASS, mrb->class_class);
-  sc->mt = 0;
+  sc->mt = kh_init(mt, mrb);
   sc->iv = 0;
   if (o->tt == MRB_TT_CLASS) {
     c = (struct RClass*)o;
@@ -188,12 +188,20 @@ mrb_define_module_under(mrb_state *mrb, struct RClass *outer, const char *name)
 }
 
 static struct RClass*
+find_origin(struct RClass *c)
+{
+  MRB_CLASS_ORIGIN(c);
+  return c;
+}
+
+static struct RClass*
 define_class(mrb_state *mrb, mrb_sym name, struct RClass *super, struct RClass *outer)
 {
   struct RClass * c;
 
   if (mrb_const_defined_at(mrb, mrb_obj_value(outer), name)) {
     c = class_from_sym(mrb, outer, name);
+    MRB_CLASS_ORIGIN(c);
     if (super && mrb_class_real(c->super) != super) {
       mrb_raisef(mrb, E_TYPE_ERROR, "superclass mismatch for Class %S (%S not %S)",
                  mrb_sym2str(mrb, name),
@@ -323,8 +331,10 @@ mrb_define_class_under(mrb_state *mrb, struct RClass *outer, const char *name, s
 MRB_API void
 mrb_define_method_raw(mrb_state *mrb, struct RClass *c, mrb_sym mid, struct RProc *p)
 {
-  khash_t(mt) *h = c->mt;
+  khash_t(mt) *h;
   khiter_t k;
+  MRB_CLASS_ORIGIN(c);
+  h = c->mt;
 
   if (!h) h = c->mt = kh_init(mt, mrb);
   k = kh_put(mt, mrb, h, mid);
@@ -817,47 +827,130 @@ boot_defclass(mrb_state *mrb, struct RClass *super)
   return c;
 }
 
-MRB_API void
-mrb_include_module(mrb_state *mrb, struct RClass *c, struct RClass *m)
+static void
+boot_initmod(mrb_state *mrb, struct RClass *mod)
 {
-  struct RClass *ins_pos;
+  mod->mt = kh_init(mt, mrb);
+}
+
+static struct RClass*
+include_class_new(mrb_state *mrb, struct RClass *m, struct RClass *super)
+{
+  struct RClass *ic = (struct RClass*)mrb_obj_alloc(mrb, MRB_TT_ICLASS, mrb->class_class);
+  if (m->tt == MRB_TT_ICLASS) {
+    m = m->c;
+  }
+  MRB_CLASS_ORIGIN(m);
+  ic->iv = m->iv;
+  ic->mt = m->mt;
+  ic->super = super;
+  if (m->tt == MRB_TT_ICLASS) {
+    ic->c = m->c;
+  } else {
+    ic->c = m;
+  }
+  return ic;
+}
+
+static int
+include_module_at(mrb_state *mrb, struct RClass *c, struct RClass *ins_pos, struct RClass *m, int search_super)
+{
+  struct RClass *p, *ic;
+  void *klass_mt = find_origin(c)->mt;
 
-  ins_pos = c;
   while (m) {
-    struct RClass *p = c, *ic;
     int superclass_seen = 0;
 
-    if (c->mt && c->mt == m->mt) {
-      mrb_raise(mrb, E_ARGUMENT_ERROR, "cyclic include detected");
-    }
-    while (p) {
-      if (c != p && p->tt == MRB_TT_CLASS) {
-        superclass_seen = 1;
-      }
-      else if (p->mt == m->mt) {
-        if (p->tt == MRB_TT_ICLASS && !superclass_seen) {
-          ins_pos = p;
+    if (m->flags & MRB_FLAG_IS_PREPENDED)
+      goto skip;
+
+    if (klass_mt && klass_mt == m->mt)
+      return -1;
+
+    p = c->super;
+    while(p) {
+      if (p->tt == MRB_TT_ICLASS) {
+        if (p->mt == m->mt) {
+          if (!superclass_seen) {
+            ins_pos = p; // move insert point
+          }
+          goto skip;
         }
-        goto skip;
+      } else if (p->tt == MRB_TT_CLASS) {
+        if (!search_super) break;
+        superclass_seen = 1;
       }
       p = p->super;
     }
-    ic = (struct RClass*)mrb_obj_alloc(mrb, MRB_TT_ICLASS, mrb->class_class);
-    if (m->tt == MRB_TT_ICLASS) {
-      ic->c = m->c;
-    }
-    else {
-      ic->c = m;
-    }
-    ic->mt = m->mt;
-    ic->iv = m->iv;
-    ic->super = ins_pos->super;
+
+    ic = include_class_new(mrb, m, ins_pos->super);
     ins_pos->super = ic;
-    mrb_field_write_barrier(mrb, (struct RBasic*)ins_pos, (struct RBasic*)ic);
+    mrb_field_write_barrier(mrb, (struct RBasic*)ins_pos, (struct RBasic*)ins_pos->super);
     ins_pos = ic;
   skip:
     m = m->super;
   }
+  return 0;
+}
+
+MRB_API void
+mrb_include_module(mrb_state *mrb, struct RClass *c, struct RClass *m)
+{
+  int changed = include_module_at(mrb, c, find_origin(c), m, 1);
+  if (changed < 0) {
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "cyclic include detected");
+  }
+}
+
+MRB_API void
+mrb_prepend_module(mrb_state *mrb, struct RClass *c, struct RClass *m)
+{
+  struct RClass *origin;
+  int changed = 0;
+
+  if (!(c->flags & MRB_FLAG_IS_PREPENDED)) {
+    origin = (struct RClass*)mrb_obj_alloc(mrb, MRB_TT_ICLASS, c);
+    origin->flags |= MRB_FLAG_IS_ORIGIN;
+    origin->super = c->super;
+    c->super = origin;
+    origin->mt = c->mt;
+    c->mt = kh_init(mt, mrb);
+    mrb_field_write_barrier(mrb, (struct RBasic*)c, (struct RBasic*)origin);
+    c->flags |= MRB_FLAG_IS_PREPENDED;
+  }
+  changed = include_module_at(mrb, c, c, m, 0);
+  if (changed < 0) {
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "cyclic prepend detected");
+  }
+}
+
+static mrb_value
+mrb_mod_prepend_features(mrb_state *mrb, mrb_value mod)
+{
+  mrb_value klass;
+
+  mrb_check_type(mrb, mod, MRB_TT_MODULE);
+  mrb_get_args(mrb, "C", &klass);
+  mrb_prepend_module(mrb, mrb_class_ptr(klass), mrb_class_ptr(mod));
+  return mod;
+}
+
+static mrb_value
+mrb_mod_prepend(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value *argv;
+  mrb_int argc, i;
+
+  mrb_get_args(mrb, "*", &argv, &argc);
+  for (i=0; i<argc; i++) {
+    mrb_check_type(mrb, argv[i], MRB_TT_MODULE);
+  }
+  while (argc--) {
+    mrb_funcall(mrb, argv[argc], "prepend_features", 1, klass);
+    mrb_funcall(mrb, argv[argc], "prepended", 1, klass);
+  }
+
+  return klass;
 }
 
 static mrb_value
@@ -931,15 +1024,12 @@ mrb_mod_ancestors(mrb_state *mrb, mrb_value self)
 {
   mrb_value result;
   struct RClass *c = mrb_class_ptr(self);
-
   result = mrb_ary_new(mrb);
-  mrb_ary_push(mrb, result, mrb_obj_value(c));
-  c = c->super;
   while (c) {
     if (c->tt == MRB_TT_ICLASS) {
       mrb_ary_push(mrb, result, mrb_obj_value(c->c));
     }
-    else if (c->tt != MRB_TT_SCLASS) {
+    else if (!(c->flags & MRB_FLAG_IS_PREPENDED)) {
       mrb_ary_push(mrb, result, mrb_obj_value(c));
     }
     c = c->super;
@@ -964,11 +1054,15 @@ mrb_mod_included_modules(mrb_state *mrb, mrb_value self)
 {
   mrb_value result;
   struct RClass *c = mrb_class_ptr(self);
+  struct RClass *origin = c;
 
+  MRB_CLASS_ORIGIN(origin);
   result = mrb_ary_new(mrb);
   while (c) {
-    if (c->tt == MRB_TT_ICLASS) {
-      mrb_ary_push(mrb, result, mrb_obj_value(c->c));
+    if (c != origin && c->tt == MRB_TT_ICLASS) {
+      if (c->c->tt == MRB_TT_MODULE) {
+        mrb_ary_push(mrb, result, mrb_obj_value(c->c));
+      }
     }
     c = c->super;
   }
@@ -980,10 +1074,11 @@ static mrb_value
 mrb_mod_initialize(mrb_state *mrb, mrb_value mod)
 {
   mrb_value b;
-
-  mrb_get_args(mrb, "&", &b);
+  struct RClass *m = mrb_class_ptr(mod);
+  boot_initmod(mrb, m); // bootstrap a newly initialized module
+  mrb_get_args(mrb, "|&", &b);
   if (!mrb_nil_p(b)) {
-    mrb_yield_with_class(mrb, b, 1, &mod, mod, mrb_class_ptr(mod));
+    mrb_yield_with_class(mrb, b, 1, &mod, mod, m);
   }
   return mod;
 }
@@ -1300,9 +1395,9 @@ mrb_class_superclass(mrb_state *mrb, mrb_value klass)
   struct RClass *c;
 
   c = mrb_class_ptr(klass);
-  c = c->super;
+  c = find_origin(c)->super;
   while (c && c->tt == MRB_TT_ICLASS) {
-    c = c->super;
+    c = find_origin(c)->super;
   }
   if (!c) return mrb_nil_value();
   return mrb_obj_value(c);
@@ -1540,8 +1635,7 @@ MRB_API struct RClass*
 mrb_module_new(mrb_state *mrb)
 {
   struct RClass *m = (struct RClass*)mrb_obj_alloc(mrb, MRB_TT_MODULE, mrb->module_class);
-  m->mt = kh_init(mt, mrb);
-
+  boot_initmod(mrb, m);
   return m;
 }
 
@@ -1900,13 +1994,14 @@ static void
 remove_method(mrb_state *mrb, mrb_value mod, mrb_sym mid)
 {
   struct RClass *c = mrb_class_ptr(mod);
-  khash_t(mt) *h = c->mt;
+  khash_t(mt) *h = find_origin(c)->mt;
   khiter_t k;
 
   if (h) {
     k = kh_get(mt, mrb, h, mid);
     if (k != kh_end(h)) {
       kh_del(mt, mrb, h, k);
+      mrb_funcall(mrb, mod, "method_removed", 1, mrb_symbol_value(mid));
       return;
     }
   }
@@ -2140,6 +2235,9 @@ mrb_init_class(mrb_state *mrb)
   mrb_define_method(mrb, mod, "class_variable_set",      mrb_mod_cvar_set,         MRB_ARGS_REQ(2)); /* 15.2.2.4.18 */
   mrb_define_method(mrb, mod, "extend_object",           mrb_mod_extend_object,    MRB_ARGS_REQ(1)); /* 15.2.2.4.25 */
   mrb_define_method(mrb, mod, "extended",                mrb_bob_init,             MRB_ARGS_REQ(1)); /* 15.2.2.4.26 */
+  mrb_define_method(mrb, mod, "prepend",                 mrb_mod_prepend,          MRB_ARGS_ANY());
+  mrb_define_method(mrb, mod, "prepended",               mrb_bob_init,             MRB_ARGS_REQ(1));
+  mrb_define_method(mrb, mod, "prepend_features",        mrb_mod_prepend_features, MRB_ARGS_REQ(1));
   mrb_define_method(mrb, mod, "include",                 mrb_mod_include,          MRB_ARGS_ANY());  /* 15.2.2.4.27 */
   mrb_define_method(mrb, mod, "include?",                mrb_mod_include_p,        MRB_ARGS_REQ(1)); /* 15.2.2.4.28 */
   mrb_define_method(mrb, mod, "append_features",         mrb_mod_append_features,  MRB_ARGS_REQ(1)); /* 15.2.2.4.10 */
@@ -2156,6 +2254,7 @@ mrb_init_class(mrb_state *mrb)
   mrb_define_method(mrb, mod, "public",                  mrb_mod_dummy_visibility, MRB_ARGS_ANY());  /* 15.2.2.4.38 */
   mrb_define_method(mrb, mod, "remove_class_variable",   mrb_mod_remove_cvar,      MRB_ARGS_REQ(1)); /* 15.2.2.4.39 */
   mrb_define_method(mrb, mod, "remove_method",           mrb_mod_remove_method,    MRB_ARGS_ANY());  /* 15.2.2.4.41 */
+  mrb_define_method(mrb, mod, "method_removed",          mrb_bob_init,             MRB_ARGS_REQ(1));
   mrb_define_method(mrb, mod, "attr_reader",             mrb_mod_attr_reader,      MRB_ARGS_ANY());  /* 15.2.2.4.13 */
   mrb_define_method(mrb, mod, "attr_writer",             mrb_mod_attr_writer,      MRB_ARGS_ANY());  /* 15.2.2.4.14 */
   mrb_define_method(mrb, mod, "to_s",                    mrb_mod_to_s,             MRB_ARGS_NONE());
diff --git a/src/gc.c b/src/gc.c
index 8bd8243f1..15e1bd423 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -498,7 +498,12 @@ gc_mark_children(mrb_state *mrb, struct RBasic *obj)
   mrb_gc_mark(mrb, (struct RBasic*)obj->c);
   switch (obj->tt) {
   case MRB_TT_ICLASS:
-    mrb_gc_mark(mrb, (struct RBasic*)((struct RClass*)obj)->super);
+    {
+      struct RClass *c = (struct RClass*)obj;
+      if (MRB_FLAG_TEST(c, MRB_FLAG_IS_ORIGIN))
+        mrb_gc_mark_mt(mrb, c);
+      mrb_gc_mark(mrb, (struct RBasic*)((struct RClass*)obj)->super);
+    }
     break;
 
   case MRB_TT_CLASS:
@@ -624,7 +629,10 @@ obj_free(mrb_state *mrb, struct RBasic *obj)
     mrb_gc_free_mt(mrb, (struct RClass*)obj);
     mrb_gc_free_iv(mrb, (struct RObject*)obj);
     break;
-
+  case MRB_TT_ICLASS:
+    if (MRB_FLAG_TEST(obj, MRB_FLAG_IS_ORIGIN))
+      mrb_gc_free_mt(mrb, (struct RClass*)obj);
+    break;
   case MRB_TT_ENV:
     {
       struct REnv *e = (struct REnv*)obj;
diff --git a/src/kernel.c b/src/kernel.c
index b5b13f874..225f7fa54 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -240,14 +240,12 @@ mrb_singleton_class_clone(mrb_state *mrb, mrb_value obj)
     /* copy singleton(unnamed) class */
     struct RClass *clone = (struct RClass*)mrb_obj_alloc(mrb, klass->tt, mrb->class_class);
 
-    if ((mrb_type(obj) == MRB_TT_CLASS) ||
-      (mrb_type(obj) == MRB_TT_SCLASS)) { /* BUILTIN_TYPE(obj) == T_CLASS */
+    if ((mrb_type(obj) == MRB_TT_CLASS) || (mrb_type(obj) == MRB_TT_SCLASS)) {
       clone->c = clone;
     }
     else {
       clone->c = mrb_singleton_class_clone(mrb, mrb_obj_value(klass));
     }
-
     clone->super = klass->super;
     if (klass->iv) {
       mrb_iv_copy(mrb, mrb_obj_value(clone), mrb_obj_value(klass));
@@ -269,6 +267,21 @@ copy_class(mrb_state *mrb, mrb_value dst, mrb_value src)
 {
   struct RClass *dc = mrb_class_ptr(dst);
   struct RClass *sc = mrb_class_ptr(src);
+  /* if the origin is not the same as the class, then the origin and
+     the current class need to be copied */
+  if (sc->flags & MRB_FLAG_IS_PREPENDED) {
+    struct RClass *c0 = sc->super;
+    struct RClass *c1 = dc;
+
+    /* copy prepended iclasses */
+    while (!(c0->flags & MRB_FLAG_IS_ORIGIN)) {
+      c1->super = mrb_class_ptr(mrb_obj_dup(mrb, mrb_obj_value(c0)));
+      c1 = c1->super;
+      c0 = c0->super;
+    }
+    c1->super = mrb_class_ptr(mrb_obj_dup(mrb, mrb_obj_value(c0)));
+    c1->super->flags |= MRB_FLAG_IS_ORIGIN;
+  }
   dc->mt = kh_copy(mt, mrb, sc->mt);
   dc->super = sc->super;
 }
@@ -641,13 +654,19 @@ mrb_class_instance_method_list(mrb_state *mrb, mrb_bool recur, struct RClass* kl
 {
   khint_t i;
   mrb_value ary;
+  mrb_bool prepended;
   struct RClass* oldklass;
   khash_t(st)* set = kh_init(st, mrb);
 
+  if (!recur && (klass->flags & MRB_FLAG_IS_PREPENDED)) {
+    MRB_CLASS_ORIGIN(klass);
+    prepended = 1;
+  }
+
   oldklass = 0;
   while (klass && (klass != oldklass)) {
     method_entry_loop(mrb, klass, set);
-    if ((klass->tt == MRB_TT_ICLASS) ||
+    if ((klass->tt == MRB_TT_ICLASS && !prepended) ||
         (klass->tt == MRB_TT_SCLASS)) {
     }
     else {
diff --git a/src/object.c b/src/object.c
index f8f41bfe8..2e0bd245f 100644
--- a/src/object.c
+++ b/src/object.c
@@ -487,6 +487,7 @@ mrb_obj_is_kind_of(mrb_state *mrb, mrb_value obj, struct RClass *c)
       mrb_raise(mrb, E_TYPE_ERROR, "class or module required");
   }
 
+  MRB_CLASS_ORIGIN(c);
   while (cl) {
     if (cl == c || cl->mt == c->mt)
       return TRUE;
diff --git a/test/t/module.rb b/test/t/module.rb
index ecb969475..4bde20fbe 100644
--- a/test/t/module.rb
+++ b/test/t/module.rb
@@ -1,6 +1,26 @@
 ##
 # Module ISO Test
 
+def labeled_module(name, &block)
+  Module.new do
+    singleton_class.class_eval do
+      define_method(:to_s) { name }
+      alias_method :inspect, :to_s
+    end
+    class_eval(&block) if block
+  end
+end
+
+def labeled_class(name, supklass = Object, &block)
+  Class.new(supklass) do
+    singleton_class.class_eval do
+      define_method(:to_s) { name }
+      alias_method :inspect, :to_s
+    end
+    class_eval(&block) if block
+  end
+end
+
 assert('Module', '15.2.2') do
   assert_equal Class, Module.class
 end
@@ -474,6 +494,286 @@ end
 
 # Not ISO specified
 
+# @!group prepend
+  assert('Module#prepend') do
+    module M0
+      def m1; [:M0] end
+    end
+    module M1
+      def m1; [:M1, super, :M1] end
+    end
+    module M2
+      def m1; [:M2, super, :M2] end
+    end
+    M3 = Module.new do
+      def m1; [:M3, super, :M3] end
+    end
+    module M4
+      def m1; [:M4, super, :M4] end
+    end
+
+    class P0
+      include M0
+      prepend M1
+      def m1; [:C0, super, :C0] end
+    end
+    class P1 < P0
+      prepend M2, M3
+      include M4
+      def m1; [:C1, super, :C1] end
+    end
+
+    obj = P1.new
+    expected = [:M2,[:M3,[:C1,[:M4,[:M1,[:C0,[:M0],:C0],:M1],:M4],:C1],:M3],:M2]
+    assert_equal(expected, obj.m1)
+  end
+
+  # mruby shouldn't be affected by this since there is
+  # no visibility control (yet)
+  assert('Module#prepend public') do
+    assert_nothing_raised('ruby/ruby #8846') do
+      Class.new.prepend(Module.new)
+    end
+  end
+
+  assert('Module#prepend inheritance') do
+    bug6654 = '[ruby-core:45914]'
+    a = labeled_module('a')
+    b = labeled_module('b') { include a }
+    c = labeled_module('c') { prepend b }
+
+    #assert bug6654 do
+      # the Module#< operator should be used here instead, but we don't have it
+      assert_include(c.ancestors, a)
+      assert_include(c.ancestors, b)
+    #end
+
+    bug8357 = '[ruby-core:54736] [Bug #8357]'
+    b = labeled_module('b') { prepend a }
+    c = labeled_class('c') { include b }
+
+    #assert bug8357 do
+      # the Module#< operator should be used here instead, but we don't have it
+      assert_include(c.ancestors, a)
+      assert_include(c.ancestors, b)
+    #end
+
+    bug8357 = '[ruby-core:54742] [Bug #8357]'
+    assert_kind_of(b, c.new, bug8357)
+  end
+
+  assert('Moduler#prepend + #instance_methods') do
+    bug6655 = '[ruby-core:45915]'
+    assert_equal(Object.instance_methods, Class.new {prepend Module.new}.instance_methods, bug6655)
+  end
+
+  assert 'Module#prepend + #singleton_methods' do
+    o = Object.new
+    o.singleton_class.class_eval {prepend Module.new}
+    assert_equal([], o.singleton_methods)
+  end
+
+  assert 'Module#prepend + #remove_method' do
+    c = Class.new do
+      prepend Module.new { def foo; end }
+    end
+    assert_raise(NameError) do
+      c.class_eval do
+        remove_method(:foo)
+      end
+    end
+    c.class_eval do
+      def foo; end
+    end
+    removed = nil
+    c.singleton_class.class_eval do
+      define_method(:method_removed) {|id| removed = id}
+    end
+    assert_nothing_raised(NoMethodError, NameError, '[Bug #7843]') do
+      c.class_eval do
+        remove_method(:foo)
+      end
+    end
+    assert_equal(:foo, removed)
+  end
+
+  assert 'Module#prepend + Class#ancestors' do
+    bug6658 = '[ruby-core:45919]'
+    m = labeled_module("m")
+    c = labeled_class("c") {prepend m}
+    assert_equal([m, c], c.ancestors[0, 2], bug6658)
+
+    bug6662 = '[ruby-dev:45868]'
+    c2 = labeled_class("c2", c)
+    anc = c2.ancestors
+    assert_equal([c2, m, c, Object], anc[0..anc.index(Object)], bug6662)
+  end
+
+  assert 'Module#prepend + Module#ancestors' do
+    bug6659 = '[ruby-dev:45861]'
+    m0 = labeled_module("m0") { def x; [:m0, *super] end }
+    m1 = labeled_module("m1") { def x; [:m1, *super] end; prepend m0 }
+    m2 = labeled_module("m2") { def x; [:m2, *super] end; prepend m1 }
+    c0 = labeled_class("c0") { def x; [:c0] end }
+    c1 = labeled_class("c1") { def x; [:c1] end; prepend m2 }
+    c2 = labeled_class("c2", c0) { def x; [:c2, *super] end; include m2 }
+    #
+    assert_equal([m0, m1], m1.ancestors, bug6659)
+    #
+    bug6662 = '[ruby-dev:45868]'
+    assert_equal([m0, m1, m2], m2.ancestors, bug6662)
+    assert_equal([m0, m1, m2, c1], c1.ancestors[0, 4], bug6662)
+    assert_equal([:m0, :m1, :m2, :c1], c1.new.x)
+    assert_equal([c2, m0, m1, m2, c0], c2.ancestors[0, 5], bug6662)
+    assert_equal([:c2, :m0, :m1, :m2, :c0], c2.new.x)
+    #
+    m3 = labeled_module("m3") { include m1; prepend m1 }
+    assert_equal([m3, m0, m1], m3.ancestors)
+    m3 = labeled_module("m3") { prepend m1; include m1 }
+    assert_equal([m0, m1, m3], m3.ancestors)
+    m3 = labeled_module("m3") { prepend m1; prepend m1 }
+    assert_equal([m0, m1, m3], m3.ancestors)
+    m3 = labeled_module("m3") { include m1; include m1 }
+    assert_equal([m3, m0, m1], m3.ancestors)
+  end
+
+  assert 'Module#prepend #instance_methods(false)' do
+    bug6660 = '[ruby-dev:45863]'
+    assert_equal([:m1], Class.new{ prepend Module.new; def m1; end }.instance_methods(false), bug6660)
+    assert_equal([:m1], Class.new(Class.new{def m2;end}){ prepend Module.new; def m1; end }.instance_methods(false), bug6660)
+  end
+
+  assert 'cyclic Module#prepend' do
+    bug7841 = '[ruby-core:52205] [Bug #7841]'
+    m1 = Module.new
+    m2 = Module.new
+    m1.instance_eval { prepend(m2) }
+    assert_raise(ArgumentError, bug7841) do
+      m2.instance_eval { prepend(m1) }
+    end
+  end
+
+  # these assertions will not run without a #assert_seperately method
+  #assert 'test_prepend_optmethod' do
+  #  bug7983 = '[ruby-dev:47124] [Bug #7983]'
+  #  assert_separately [], %{
+  #    module M
+  #      def /(other)
+  #        to_f / other
+  #      end
+  #    end
+  #    Fixnum.send(:prepend, M)
+  #    assert_equal(0.5, 1 / 2, "#{bug7983}")
+  #  }
+  #  assert_equal(0, 1 / 2)
+  #end
+
+  # mruby has no visibility control
+  assert 'Module#prepend visibility' do
+    bug8005 = '[ruby-core:53106] [Bug #8005]'
+    c = Class.new do
+      prepend Module.new {}
+      def foo() end
+      protected :foo
+    end
+    a = c.new
+    assert_true a.respond_to?(:foo), bug8005
+    assert_nothing_raised(NoMethodError, bug8005) {a.send :foo}
+  end
+
+  # mruby has no visibility control
+  assert 'Module#prepend inherited visibility' do
+    bug8238 = '[ruby-core:54105] [Bug #8238]'
+    module Test4PrependVisibilityInherited
+      class A
+        def foo() A; end
+        private :foo
+      end
+      class B < A
+        public :foo
+        prepend Module.new
+      end
+    end
+    assert_equal(Test4PrependVisibilityInherited::A, Test4PrependVisibilityInherited::B.new.foo, "#{bug8238}")
+  end
+
+  assert 'Module#prepend + #included_modules' do
+    bug8025 = '[ruby-core:53158] [Bug #8025]'
+    mixin = labeled_module("mixin")
+    c = labeled_module("c") {prepend mixin}
+    im = c.included_modules
+    assert_not_include(im, c, bug8025)
+    assert_include(im, mixin, bug8025)
+    c1 = labeled_class("c1") {prepend mixin}
+    c2 = labeled_class("c2", c1)
+    im = c2.included_modules
+    assert_not_include(im, c1, bug8025)
+    assert_not_include(im, c2, bug8025)
+    assert_include(im, mixin, bug8025)
+  end
+
+  assert 'Module#prepend super in alias' do
+    skip "super does not currently work in aliased methods"
+    bug7842 = '[Bug #7842]'
+
+    p = labeled_module("P") do
+      def m; "P"+super; end
+    end
+
+    a = labeled_class("A") do
+      def m; "A"; end
+    end
+
+    b = labeled_class("B", a) do
+      def m; "B"+super; end
+      alias m2 m
+      prepend p
+      alias m3 m
+    end
+
+    assert_nothing_raised do
+      assert_equal("BA", b.new.m2, bug7842)
+    end
+
+    assert_nothing_raised do
+      assert_equal("PBA", b.new.m3, bug7842)
+    end
+  end
+
+  assert 'Module#prepend each class' do
+    m = labeled_module("M")
+    c1 = labeled_class("C1") {prepend m}
+    c2 = labeled_class("C2", c1) {prepend m}
+    assert_equal([m, c2, m, c1], c2.ancestors[0, 4], "should be able to prepend each class")
+  end
+
+  assert 'Module#prepend no duplication' do
+    m = labeled_module("M")
+    c = labeled_class("C") {prepend m; prepend m}
+    assert_equal([m, c], c.ancestors[0, 2], "should never duplicate")
+  end
+
+  assert 'Module#prepend in superclass' do
+    m = labeled_module("M")
+    c1 = labeled_class("C1")
+    c2 = labeled_class("C2", c1) {prepend m}
+    c1.class_eval {prepend m}
+    assert_equal([m, c2, m, c1], c2.ancestors[0, 4], "should accesisble prepended module in superclass")
+  end
+
+  # requires #assert_seperately
+  #assert 'Module#prepend call super' do
+  #  assert_separately([], <<-'end;') #do
+  #    bug10847 = '[ruby-core:68093] [Bug #10847]'
+  #    module M; end
+  #    Float.prepend M
+  #    assert_nothing_raised(SystemStackError, bug10847) do
+  #      0.3.numerator
+  #    end
+  #  end;
+  #end
+# @!endgroup prepend
+
 assert('Module#to_s') do
   module Test4to_sModules
   end