Bug#39559: dump of stored procedures / functions with C-style \

	comment can't be read back

A change to the lexer in 5.1 caused slash-asterisk-bang-version
sections to be terminated early if there exists a slash-asterisk-
style comment inside it.  Nesting comments is usually illegal,
but we rely on versioned comment blocks in mysqldump, and the
contents of those sections must be allowed to have comments.

The problem was that when encountering open-comment tokens and
consuming -or- passing through the contents, the "in_comment"
state at the end was clobbered with the not-in-a-comment value,
regardless of whether we were in a comment before this or not.  

So, """/*!VER one /* two */ three */""" would lose its in-comment
state between "two" and "three".  Save the echo and in-comment
state, and restore it at the end of the comment if we consume a 
comment.

mysql-test/r/parser.result

@@ -615,3 +615,55 @@ UPDATE t3 SET a4={d '1789-07-14'} WHERE a1=0;
 SELECT a1, a4 FROM t2 WHERE a4 LIKE {fn UCASE('1789-07-14')};
 a1	a4
 DROP TABLE t1, t2, t3;
+#
+# Bug#39559: dump of stored procedures / functions with C-style 
+#     comment can't be read back
+#
++----------+--------+
+| expected | result |
++----------+--------+
+|        2 |      2 | 
++----------+--------+
++----------+--------+
+| expected | result |
++----------+--------+
+|        1 |      1 | 
++----------+--------+
++----------+--------+
+| expected | result |
++----------+--------+
+|        3 |      3 | 
++----------+--------+
++----------+--------+
+| expected | result |
++----------+--------+
+|        2 |      2 | 
++----------+--------+
++----------+--------+
+| expected | result |
++----------+--------+
+|        7 |      7 | 
++----------+--------+
++----------+--------+
+| expected | result |
++----------+--------+
+|        8 |      8 | 
++----------+--------+
++----------+--------+
+| expected | result |
++----------+--------+
+|        7 |      7 | 
++----------+--------+
++----------+--------+
+| expected | result |
++----------+--------+
+|        4 |      4 | 
++----------+--------+
++----------+--------+
+| expected | result |
++----------+--------+
+|        4 |      4 | 
++----------+--------+
+#
+# End of 5.1 tests
+#

mysql-test/t/parser.test

@@ -724,3 +724,31 @@ SELECT {fn CONCAT(a1,a2)} FROM t1;
 UPDATE t3 SET a4={d '1789-07-14'} WHERE a1=0;
 SELECT a1, a4 FROM t2 WHERE a4 LIKE {fn UCASE('1789-07-14')};
 DROP TABLE t1, t2, t3;
+
+###########################################################################
+--echo #
+--echo # Bug#39559: dump of stored procedures / functions with C-style 
+--echo #     comment can't be read back
+--echo #
+
+--write_file $MYSQLTEST_VARDIR/tmp/bug39559.sql
+select 2 as expected, /*!01000/**/*/ 2 as result;
+select 1 as expected, /*!99998/**/*/ 1 as result;
+select 3 as expected, /*!01000 1 + */ 2 as result;
+select 2 as expected, /*!99990 1 + */ 2 as result;
+select 7 as expected, /*!01000 1 + /* 8 + */ 2 + */ 4 as result;
+select 8 as expected, /*!99998 1 + /* 2 + */ 4 + */ 8 as result;
+select 7 as expected, /*!01000 1 + /*!01000 8 + */ 2 + */ 4 as result;
+select 7 as expected, /*!01000 1 + /*!99998 8 + */ 2 + */ 4 as result;
+select 4 as expected, /*!99998 1 + /*!99998 8 + */ 2 + */ 4 as result;
+select 4 as expected, /*!99998 1 + /*!01000 8 + */ 2 + */ 4 as result;
+select 7 as expected, /*!01000 1 + /*!01000 8 + /*!01000 error */ 16 + */ 2 + */ 4 as result;
+select 4 as expected, /* 1 + /*!01000 8 + */ 2 + */ 4;
+EOF
+
+--exec $MYSQL --comment --force --table test <$MYSQLTEST_VARDIR/tmp/bug39559.sql
+--remove_file $MYSQLTEST_VARDIR/tmp/bug39559.sql
+
+--echo #
+--echo # End of 5.1 tests
+--echo #

sql/sql_lex.cc

@@ -712,6 +712,53 @@ static inline uint int_token(const char *str,uint length)
   return ((uchar) str[-1] <= (uchar) cmp[-1]) ? smaller : bigger;
 }
 
+
+/**
+  Given a stream that is advanced to the first contained character in 
+  an open comment, consume the comment.  Optionally, if we are allowed, 
+  recurse so that we understand comments within this current comment.
+
+  At this level, we do not support version-condition comments.  We might 
+  have been called with having just passed one in the stream, though.  In 
+  that case, we probably want to tolerate mundane comments inside.  Thus,
+  the case for recursion.
+
+  @retval  Whether EOF reached before comment is closed.
+*/
+bool consume_comment(Lex_input_stream *lip, int remaining_recursions_permitted)
+{
+  reg1 uchar c;
+  while (! lip->eof())
+  {
+    c= lip->yyGet();
+
+    if (remaining_recursions_permitted > 0)
+    {
+      if ((c == '/') && (lip->yyPeek() == '*'))
+      {
+        lip->yySkip(); /* Eat asterisk */
+        consume_comment(lip, remaining_recursions_permitted-1);
+        continue;
+      }
+    }
+
+    if (c == '*')
+    {
+      if (lip->yyPeek() == '/')
+      {
+        lip->yySkip(); /* Eat slash */
+        return FALSE;
+      }
+    }
+
+    if (c == '\n')
+      lip->yylineno++;
+  }
+
+  return TRUE;
+}
+
+
 /*
   MYSQLlex remember the following states from the following MYSQLlex()
 
@@ -1204,6 +1251,8 @@ int MYSQLlex(void *arg, void *yythd)
       /* Reject '/' '*', since we might need to turn off the echo */
       lip->yyUnget();
 
+      lip->save_in_comment_state();
+
       if (lip->yyPeekn(2) == '!')
       {
         lip->in_comment= DISCARD_COMMENT;
@@ -1246,11 +1295,17 @@ int MYSQLlex(void *arg, void *yythd)
             /* Expand the content of the special comment as real code */
             lip->set_echo(TRUE);
             state=MY_LEX_START;
-            break;
+            break;  /* Do not treat contents as a comment.  */
+          }
+          else
+          {
+            comment_closed= ! consume_comment(lip, 1);
+            /* version allowed to have one level of comment inside. */
           }
         }
         else
         {
+          /* Not a version comment. */
           state=MY_LEX_START;
           lip->set_echo(TRUE);
           break;
@@ -1261,38 +1316,30 @@ int MYSQLlex(void *arg, void *yythd)
         lip->in_comment= PRESERVE_COMMENT;
         lip->yySkip();                  // Accept /
         lip->yySkip();                  // Accept *
+        comment_closed= ! consume_comment(lip, 0);
+        /* regular comments can have zero comments inside. */
       }
       /*
         Discard:
         - regular '/' '*' comments,
         - special comments '/' '*' '!' for a future version,
         by scanning until we find a closing '*' '/' marker.
-        Note: There is no such thing as nesting comments,
-        the first '*' '/' sequence seen will mark the end.
+
+        Nesting regular comments isn't allowed.  The first 
+        '*' '/' returns the parser to the previous state.
+
+        /#!VERSI oned containing /# regular #/ is allowed #/
+
+		Inside one versioned comment, another versioned comment
+		is treated as a regular discardable comment.  It gets
+		no special parsing.
       */
-      comment_closed= FALSE;
-      while (! lip->eof())
-      {
-        c= lip->yyGet();
-        if (c == '*')
-        {
-          if (lip->yyPeek() == '/')
-          {
-            lip->yySkip();
-            comment_closed= TRUE;
-            state = MY_LEX_START;
-            break;
-          }
-        }
-        else if (c == '\n')
-          lip->yylineno++;
-      }
+
       /* Unbalanced comments with a missing '*' '/' are a syntax error */
       if (! comment_closed)
         return (ABORT_SYM);
       state = MY_LEX_START;             // Try again
-      lip->in_comment= NO_COMMENT;
-      lip->set_echo(TRUE);
+      lip->restore_in_comment_state();
       break;
     case MY_LEX_END_LONG_COMMENT:
       if ((lip->in_comment != NO_COMMENT) && lip->yyPeek() == '/')

sql/sql_lex.h

@@ -1160,6 +1160,18 @@ public:
     m_echo= echo;
   }
 
+  void save_in_comment_state()
+  {
+    m_echo_saved= m_echo;
+    in_comment_saved= in_comment;
+  }
+
+  void restore_in_comment_state()
+  {
+    m_echo= m_echo_saved;
+    in_comment= in_comment_saved;
+  }
+
   /**
     Skip binary from the input stream.
     @param n number of bytes to accept.
@@ -1417,6 +1429,7 @@ private:
 
   /** Echo the parsed stream to the pre-processed buffer. */
   bool m_echo;
+  bool m_echo_saved;
 
   /** Pre-processed buffer. */
   char *m_cpp_buf;
@@ -1479,6 +1492,7 @@ public:
 
   /** State of the lexical analyser for comments. */
   enum_comment_state in_comment;
+  enum_comment_state in_comment_saved;
 
   /**
     Starting position of the TEXT_STRING or IDENT in the pre-processed