Re: [Boost-bugs] [Boost C++ Libraries] #8564: Variable hiding errors within nested let blocks in Phoenix

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #8564: Variable hiding errors within nested let blocks in Phoenix
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-02-09 18:32:30

#8564: Variable hiding errors within nested let blocks in Phoenix
-------------------------------+---------------------
  Reporter:  miremare@…        |      Owner:  theller
      Type:  Bugs              |     Status:  new
 Milestone:  To Be Determined  |  Component:  phoenix
   Version:  Boost 1.53.0      |   Severity:  Problem
Resolution:                    |   Keywords:
-------------------------------+---------------------

Comment (by John Fletcher <J.P.Fletcher@…>):

 Replying to [comment:2 John Fletcher <J.P.Fletcher@…>]:
 > Further work has shown that these cases work as expected
 > {{{
 >   {
 >     int z = 3;
 >     int y = 0;
 >     int x = (phoenix::let(_a = 1, _b = 2)[phoenix::let(_b = _a)[ _a
 ]])(y);
 >   }
 > }}}
 > {{{
 >   {
 >     int y = 0;
 >     int x = (phoenix::let(_a = 1, _b = 2)[phoenix::let(_b = _1)[ _a
 ]])(y);
 >   }
 > }}}
 > {{{
 >   {
 >     int y = 0;
 >     int x = (phoenix::let(_a = 1, _b = 2)[phoenix::let(_b = 1)[_b]])();
 >   }  // This works....
 > }}}
 > but this case fails:
 > {{{
 >   {
 >     int y = 0;
 >     int x = (phoenix::let(_a = 1, _b = 2)[phoenix::let(_b = 1)[_a]])();
 >   }
 > }}}
 > Reference to _a in the inner loop is the problem, but only when _b is
 set to a constant!!
 >
 > Further investigation is in progress.

 Unfortunately it is not as easy as that. The 'working' cases above fail
 for some compilers e.g. clang 3.4 in C++03 but not C++11. gcc 4.8.2 works
 for C++03 and C++11. Work is in progress.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/8564#comment:3>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.