Index: boost/regex/v4/basic_regex_creator.hpp
===================================================================
--- boost/regex/v4/basic_regex_creator.hpp	(revision 84007)
+++ boost/regex/v4/basic_regex_creator.hpp	(working copy)
@@ -738,14 +738,14 @@
       case syntax_element_long_set_rep:
          // set the state_id of this repeat:
          static_cast<re_repeat*>(state)->state_id = m_repeater_id++;
-         // fall through:
+         BOOST_FALLTHROUGH;
       case syntax_element_alt:
          std::memset(static_cast<re_alt*>(state)->_map, 0, sizeof(static_cast<re_alt*>(state)->_map));
          static_cast<re_alt*>(state)->can_be_null = 0;
-         // fall through:
+         BOOST_FALLTHROUGH;
       case syntax_element_jump:
          static_cast<re_jump*>(state)->alt.p = getaddress(static_cast<re_jump*>(state)->alt.i, state);
-         // fall through again:
+         BOOST_FALLTHROUGH;
       default:
          if(state->next.i)
             state->next.p = getaddress(state->next.i, state);
@@ -877,6 +877,7 @@
                }
             }
          }
+         break;
       default:
          break;
       }
@@ -941,7 +942,7 @@
                e.raise();
             }
          }
-         // fall through:
+         BOOST_FALLTHROUGH;
       default:
          state = state->next.p;
       }
@@ -1153,13 +1154,14 @@
                break;
             }
             m_recursion_checks[recursion_sub] = true;
-            // fall through, can't handle nested recursion here...
+            // can't handle nested recursion here...
+            BOOST_FALLTHROUGH;
          }
       case syntax_element_backref:
          // can be null, and any character can match:
          if(pnull)
             *pnull |= mask;
-         // fall through:
+         BOOST_FALLTHROUGH;
       case syntax_element_wild:
       {
          // can't be null, any character can match:
@@ -1359,7 +1361,7 @@
             state = state->next.p->next.p;
             break;
          }
-         // otherwise fall through:
+         BOOST_FALLTHROUGH;
       default:
          state = state->next.p;
       }
@@ -1456,6 +1458,7 @@
          if(state_id <= sizeof(m_bad_repeats) * CHAR_BIT)
             m_bad_repeats |= (one << state_id);
       }
+      break;
    default:
       break;
    }
@@ -1537,7 +1540,7 @@
       case syntax_element_long_set_rep:
          if(this->m_has_backrefs == 0)
             static_cast<re_repeat*>(state)->leading = true;
-         // fall through:
+         BOOST_FALLTHROUGH;
       default:
          return;
       }
Index: boost/regex/v4/basic_regex_parser.hpp
===================================================================
--- boost/regex/v4/basic_regex_parser.hpp	(revision 84007)
+++ boost/regex/v4/basic_regex_parser.hpp	(working copy)
@@ -369,7 +369,7 @@
          while((m_position != m_end) && !is_separator(*m_position++)){}
          return true;
       }
-      // Otherwise fall through:
+      BOOST_FALLTHROUGH;
    default:
       result = parse_literal();
       break;
@@ -623,7 +623,7 @@
          {
          case 'w':
             negate = false;
-            // fall through:
+            BOOST_FALLTHROUGH;
          case 'W':
             {
             basic_char_set<charT, traits> char_set;
@@ -640,7 +640,7 @@
             }
          case 's':
             negate = false;
-            // fall through:
+            BOOST_FALLTHROUGH;
          case 'S':
             return add_emacs_code(negate);
          case 'c':
@@ -672,7 +672,7 @@
    {
    case regex_constants::escape_type_not_class:
       negate = true;
-      // fall through:
+      BOOST_FALLTHROUGH;
    case regex_constants::escape_type_class:
       {
 escape_type_class_jump:
@@ -742,7 +742,7 @@
       break;
    case regex_constants::escape_type_not_property:
       negate = true;
-      // fall through:
+      BOOST_FALLTHROUGH;
    case regex_constants::escape_type_property:
       {
          ++m_position;
@@ -901,7 +901,7 @@
    case regex_constants::escape_type_control_v:
       if(0 == (this->flags() & (regbase::main_option_type | regbase::no_perl_ex)))
          goto escape_type_class_jump;
-      // fallthrough:
+      BOOST_FALLTHROUGH;
    default:
       this->append_literal(unescape_character());
       break;
@@ -1959,7 +1959,7 @@
    {
    case regex_constants::syntax_or:
       m_mark_reset = m_mark_count;
-      // fall through:
+      BOOST_FALLTHROUGH;
    case regex_constants::syntax_colon:
       //
       // a non-capturing mark:
Index: boost/regex/v4/regex_format.hpp
===================================================================
--- boost/regex/v4/regex_format.hpp	(revision 84007)
+++ boost/regex/v4/regex_format.hpp	(working copy)
@@ -283,7 +283,8 @@
             format_perl();
             break;
          }
-         // fall through, not a special character:
+         // not a special character:
+         BOOST_FALLTHROUGH;
       default:
          put(*m_position);
          ++m_position;
@@ -354,7 +355,7 @@
    case '{':
       have_brace = true;
       ++m_position;
-      // fall through....
+      BOOST_FALLTHROUGH;
    default:
       // see if we have a number:
       {