Re: compile error: Rapicorn 15.09 on Ubuntu 14.04

[Stefan Westerfeld <stefan space twc de>]

   Hi!

On Mon, Sep 28, 2015 at 12:56:43PM +0200, Tim Janik wrote:
> On 22.09.2015 17:12, Tim Janik wrote:
> > Hey Stefan,
> >
> > I've taken a look at the g++4-.8 build error on Ubuntu-14.04 you reported.
> > Turns out I don't need a 14.04 docker containe rto reproduce this, my Ubuntu-15.04
> > also ships g++-4.8.real (Ubuntu 4.8.4-1ubuntu15) 4.8.4.
> >
> > It looks like g++-4.8 has problems with C++11 "delegate constructors", even though g++-4.7
> > should already have gotten full support: https://gcc.gnu.org/projects/cxx0x.html
> >
> > Attached is a stupid workaround that compiles rcore/aida.cc.
>
> Hm, bad news here.
> G++-4.9 chokes on the workaround for g++-4.8, so I cannot apply a fix like this to master.
> I don't currently have an idea what approach would work for both compiler versions, suggestions welcome...
>
>   CXX      aida.lo
> In file included from aida.cc:2:0:
> aida.hh: In instantiation of 'Rapicorn1509::Aida::Any::Any(V&&) [with V = Rapicorn1509::Aida::Fix1; 
> typename std::enable_if<(! std::is_base_of<Rapicorn1509::Aida::Any, typename std::remove_reference< 
> <template-parameter-1-1> >::type>::value), bool>::type <anonymous> = 1u]':
> aida.cc:325:14:   required from here
> aida.hh:285:41: error: constructor delegates to itself
>
> 284ff:
>   /// Initialize Any and set its contents from @a value.                                                    
>                            
>   template<class V, REQUIRES< !::std::is_base_of< Any, typename std::remove_reference<V>::type >::value > = 
> true> inline
>   explicit  Any    (V &&value) : Any (Fix1())  { set (::std::forward<V> (value)); }

Here is a patch that makes the rcore dir compile on both: kubuntu14.04 and 15.04.

diff --git a/rcore/aida.hh b/rcore/aida.hh
index b77ca2f..20ad8a0 100644
--- a/rcore/aida.hh
+++ b/rcore/aida.hh
@@ -275,7 +275,8 @@ private:
   void    rekind  (TypeKind _kind);
 public:
   /*dtor*/ ~Any    ();                                  ///< Any destructor.
-  explicit  Any    ();                                  ///< Default initialize Any with no type.
+  /* FIXME: removed explicit keyword to compile under g++-4.8.4 */
+  /*ctor*/  Any    ();                                  ///< Default initialize Any with no type.
   /// Initialize Any from a @a anany which is of Any or derived type.
   template<class V, REQUIRES< ::std::is_base_of< Any, typename std::remove_reference<V>::type >::value > = 
true> inline
   explicit  Any (V &&anany) : Any()     { this->operator= (::std::forward<V> (anany)); }

This change doesn't need to stay in forever, only so long as we see that many
people rely on g++-4.8.

   Cu... Stefan
-- 
Stefan Westerfeld, http://space.twc.de/~stefan