[Boost-bugs] [Boost C++ Libraries] #2225: gcc 4.4.0 pre-processor fails on BOOST_PP_ITERATION_DEPTH

Subject: [Boost-bugs] [Boost C++ Libraries] #2225: gcc 4.4.0 pre-processor fails on BOOST_PP_ITERATION_DEPTH
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-08-19 08:47:44

#2225: gcc 4.4.0 pre-processor fails on BOOST_PP_ITERATION_DEPTH
-----------------------------------------------------+----------------------
 Reporter:  Chris Fairles <chris.fairles_at_[hidden]>  |       Owner:  agurtovoy
     Type:  Bugs                                     |      Status:  new      
Milestone:  Boost 1.36.0                             |   Component:  mpl      
  Version:  Boost 1.36.0                             |    Severity:  Problem  
 Keywords:                                           |  
-----------------------------------------------------+----------------------
 Due to a gcc pre-processor change (
 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36320 ), an #elif without a
 constant-expression that is not skipped by a previous #if/elif throws a
 syntax error. This occurs in MPL on lines like:

 #elif BOOST_PP_ITERATION_DEPTH() == 1

 when BOOST_PP_ITERATION_DEPTH is not defined. The cpp sees this as:
 #elif () == 1
 and then throws an error.

 Attached is a patch that fixes this by first testing if
 BOOST_PP_ITERATION_DEPTH is defined before testing the macro function
 expansion.

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/2225>
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