1 files changed, 74 insertions, 21 deletions

diff --git a/build2/target.ixx b/build2/target.ixx
index d89ed08..5cf5ca9 100644
--- a/build2/target.ixx
+++ b/build2/target.ixx
@@ -21,6 +21,11 @@ namespace build2
     if (target == nullptr)
       return prerequisite;
 
+    // An ad hoc group member cannot be used as a prerequisite (use the whole
+    // group instead).
+    //
+    assert (!target->adhoc_member ());
+
     // The use of the group's prerequisite scope is debatable.
     //
     scope& s (prerequisite.get ().scope);
@@ -36,24 +41,32 @@ namespace build2
   inline auto prerequisite_members_range<T>::iterator::
   operator++ () -> iterator&
   {
-    if (g_.count != 0)
+    if (k_ != nullptr) // Iterating over an ad hoc group.
+      k_ = k_->member;
+    else if (r_->members_)
     {
-      if (++j_ <= g_.count)
-        return *this;
-
-      // Switch back to prerequisite iteration mode.
+      // Get the target if one has been resolved and see if it's an ad hoc
+      // group. If so, switch to the ad hoc mode.
       //
-      g_.count = 0;
+      target* t (g_.count != 0
+                 ? j_ != 0 ? g_.members[j_ - 1] : nullptr // enter_group()
+                 : i_->get ().target);
+      if (t != nullptr && t->member != nullptr)
+        k_ = t->member;
     }
 
-    ++i_;
+    if (k_ == nullptr && g_.count != 0) // Iterating over a normal group.
+    {
+      if (++j_ > g_.count)
+        g_.count = 0;
+    }
 
-    // Switch to member iteration mode.
-    //
-    if (r_->members_ && i_ != r_->e_ && i_->get ().type.see_through)
+    if (k_ == nullptr && g_.count == 0) // Iterating over the range.
     {
-      bool r (switch_members ());
-      assert (r); // Group could not be resolved.
+      ++i_;
+
+      if (r_->members_ && i_ != r_->e_ && i_->get ().type.see_through)
+        switch_mode ();
     }
 
     return *this;
@@ -61,25 +74,65 @@ namespace build2
 
   template <typename T>
   inline bool prerequisite_members_range<T>::iterator::
-  switch_members ()
+  enter_group ()
   {
-    do
+    // First see if we are about to enter an ad hoc group (the same code as in
+    // operator++() above).
+    //
+    target* t (g_.count != 0
+               ? j_ != 0 ? g_.members[j_ - 1] : nullptr
+               : i_->get ().target);
+
+    if (t != nullptr && t->member != nullptr)
+      k_ = t->member;
+    else
     {
+      // Otherwise assume it is a normal group.
+      //
       g_ = resolve_group_members (r_->a_, search (*i_));
 
-      // If members are not know, iterate over the group as itself.
-      //
-      if (g_.members == nullptr)
+      if (g_.members == nullptr) // Members are not know.
       {
         g_.count = 0;
         return false;
       }
+
+      if (g_.count != 0) // Group is not empty.
+        j_ = 0; // Account for the increment that will follow.
     }
-    while (g_.count == 0  && // Skip empty groups.
-           ++i_ != r_->e_ &&
-           i_->get ().type.see_through);
 
-    j_ = 1; // Start from the first group member.
+
     return true;
   }
+
+  template <typename T>
+  inline void prerequisite_members_range<T>::iterator::
+  leave_group ()
+  {
+    // First see if we are about to enter an ad hoc group (the same code as in
+    // operator++() above).
+    //
+    if (k_ == nullptr)
+    {
+      target* t (g_.count != 0
+                 ? j_ != 0 ? g_.members[j_ - 1] : nullptr
+                 : i_->get ().target);
+      if (t != nullptr && t->member != nullptr)
+        k_ = t->member;
+    }
+
+    if (k_ != nullptr)
+    {
+      // Skip until the last element (next increment will reach the end).
+      //
+      for (; k_->member != nullptr; k_ = k_->member) ;
+    }
+    else
+    {
+      // Pretend we are on the last member of a normal group.
+      //
+      j_ = 0;
+      g_.count = 1;
+    }
+  }
 }