Re: Regression in Bison 3.2 with variant semantic values in C++ parsers

[Sébastien Villemot]

Le mardi 20 novembre 2018 à 18:33 +0100, Akim Demaille a écrit :
> Le 20 nov. 2018 à 15:21, Sébastien Villemot <address@hidden> a écrit :
> > Between Bison 3.0 and 3.2, a regression has appeared in C++ parsers
> > with variant semantic values. More precisely, it is no longer possible
> > to use a C++ type which has a comma in it (e.g. pair<int,int>), since
> > that interferes with a macro that has been introduced.
> > 
> > I attach a minimal example. It compiles fine with Bison 3.0, but with
> > Bison 3.2 I get:
> > 
> > In file included from test.yy:7:
> > test.tab.hh:507:77: error: macro "YY_RVREF" passed 2 arguments, but takes 
> > just 1
> >        basic_symbol (typename Base::kind_type t, YY_RVREF 
> > (std::pair<int,int>) v);
> >                                                                             
> >  ^
> > test.tab.cc:178:101: error: macro "YY_RVREF" passed 2 arguments, but takes 
> > just 1
> >    parser::basic_symbol<Base>::basic_symbol (typename Base::kind_type t, 
> > YY_RVREF (std::pair<int,int>) v)
> >                                                                             
> >                          ^
> > In file included from test.yy:7:
> > test.tab.hh:507:49: error: 'YY_RVREF' has not been declared
> >        basic_symbol (typename Base::kind_type t, YY_RVREF 
> > (std::pair<int,int>) v);
> >                                                  ^~~~~~~~
> > test.tab.cc:178:73: error: 'YY_RVREF' has not been declared
> >    parser::basic_symbol<Base>::basic_symbol (typename Base::kind_type t, 
> > YY_RVREF (std::pair<int,int>) v)
> >                                                                          
> > ^~~~~~~~
> > 
> > Maybe you don't consider this as a bug (since it can be easily worked
> > around with a typedef/using), but at the very least it should be
> > documented.
> 
> Rest assured that this is definitely a bug.  A stupid one actually.
> 
> I’ll wrap a 3.2.2 asap.

Great, thanks. I confirm that your bison-3.2.1.9-1e55d.tar.xz tarball
fixes the issue. So I'm looking forward for the 3.2.2 release.

> What project was hit?

Dynare (see http://www.dynare.org)

I pushed the following workaround: 
https://git.dynare.org/Dynare/preprocessor/commit/e22aa1c16258fc48bcfb53fde4a098899fce2d12

So far no numbered release is affected, the problem only affects the
development branch (where we recently took advantage of variant
semantic types).

Best,

-- 
⢀⣴⠾⠻⢶⣦⠀  Sébastien Villemot
⣾⠁⢠⠒⠀⣿⡁  Debian Developer
⢿⡄⠘⠷⠚⠋⠀  http://sebastien.villemot.name
⠈⠳⣄⠀⠀⠀⠀  http://www.debian.org

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