Re: [Boost-bugs] [Boost C++ Libraries] #8408: Boost is not compatible with Clang's -Wimplicit-fallthrough diagnostic

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #8408: Boost is not compatible with Clang's -Wimplicit-fallthrough diagnostic
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-04-08 17:38:53

#8408: Boost is not compatible with Clang's -Wimplicit-fallthrough diagnostic
------------------------------------------------------+---------------------
  Reporter:  Alexander Kornienko <alexfh@…>           |       Owner:  johnmaddock
      Type:  Patches                                  |      Status:  new        
 Milestone:  To Be Determined                         |   Component:  config     
   Version:  Boost Development Trunk                  |    Severity:  Problem    
Resolution:                                           |    Keywords:             
------------------------------------------------------+---------------------

Comment (by Alexander Kornienko <alexfh@…>):

 Replying to [comment:4 johnmaddock]:
 > >For the second part, are you saying this will require a separate ticket
 and patch for each library that's updated to use the annotation?
 >
 > That would certainly increase the chance of acceptance.

 Thanks for clarification.

 > One thing about your patches though: some compilers (GCC?) will warn if
 there are empty statements - which is exactly what your warning patch will
 generate on non-clang compilers.
 >
 > So BOOST_FALLTHROUGH needs to be defined to be used without a following
 ";".

 On unsupported compilers (or in non-C++11 mode in Clang) it expands to "do
 {} while(0)", which requires a semicolon as well. This construct was meant
 to look and behave consistently with 'break;' statement, which it can be
 an alternative to in many cases. So requiring a semicolon after it seems
 to be reasonable.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/8408#comment:5>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.