Pushing null values into a sequence is legitimate

src/interactive.cc

@@ -62,6 +62,8 @@ void interactive_t::verify_arguments() const
   for (; ! wrong_arg && ! exit_loop && *p && next_arg; p++) {
     DEBUG("interactive.verify",
 	  "Want " << *p << " got: " << next_arg->label());
+
+    wrong_arg = false;
     switch (*p) {
     case 'a':
       label = _("an amount");
@@ -134,6 +136,8 @@ void interactive_t::verify_arguments() const
       dont_skip = true;
       break;
     }
+    if (wrong_arg && optional && next_arg->is_null())
+      wrong_arg = false;
 
     if (wrong_arg)
       vlabel = next_arg->label();

src/value.h

@@ -818,14 +818,12 @@ public:
   }
 
   void push_back(const value_t& val) {
-    if (! val.is_null()) {
     if (is_null())
       *this = sequence_t();
     if (! is_sequence())
       in_place_cast(SEQUENCE);
     as_sequence_lval().push_back(val);
   }
-  }
 
   void pop_back() {
     VERIFY(! is_null());
@@ -855,24 +853,18 @@ public:
   }
 
   sequence_t::iterator begin() {
-    VERIFY(is_sequence());
     return as_sequence_lval().begin();
   }
 
   sequence_t::iterator end() {
-    VERIFY(is_sequence());
+    return as_sequence_lval().end();
-    // This special hack is because we never used end() in a context which
-    // needs us to call _dup().
-    return boost::get<sequence_t *>(storage->data)->end();
   }
 
   sequence_t::const_iterator begin() const {
-    VERIFY(is_sequence());
     return as_sequence().begin();
   }
 
   sequence_t::const_iterator end() const {
-    VERIFY(is_sequence());
     return as_sequence().end();
   }