Re: [Boost-bugs] [Boost C++ Libraries] #7679: unhex level 4 compile warning in visual studio

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #7679: unhex level 4 compile warning in visual studio
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-11-11 03:05:15

#7679: unhex level 4 compile warning in visual studio
-----------------------------------------------+----------------------------
  Reporter:  Gary Sanders <lex21@…>            |       Owner:  marshall 
      Type:  Bugs                              |      Status:  new      
 Milestone:  To Be Determined                  |   Component:  algorithm
   Version:  Boost 1.52.0                      |    Severity:  Problem  
Resolution:                                    |    Keywords:  unhex    
-----------------------------------------------+----------------------------

Comment (by marshall):

 This is a crap warning.

 There is no loss of data here.

 The routine `hex_char_to_int` only returns values in the range 0..15.

 With `T` == `char`, the loop at line 134 will be executed twice.

 `res` is initialized to zero.

 The first time through the loop, we multiply `res` (0) * 16 + add the
 result of `hex_char_to_int`,  so the maximum value that `res` can be is
 15.

 The second time through the loop, we multiply `res` * 16 and add the
 result of `hex_char_to_int`, so the maximum value that `res` can be is
 (15*16) + 15, or 255.

 No overflow; no loss of data.

 Please file a bug report with your compiler vendor.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/7679#comment:1>
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