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Re: Comments in %union processed incorrectly

From: Hans Aberg
Subject: Re: Comments in %union processed incorrectly
Date: Thu, 3 Jan 2002 12:29:53 +0100

At 10:15 +0100 2002/01/03, Akim Demaille wrote:
>>> The problem is that we now use an union to compute the alignments,
>>> and only for that.  It just happens that I do have a Location
>>> class, which does have ctors.  But now, because of this single
>>> union, this is no longer proper C++: classes with ctors cannot be
>>> stored in a union.
>>> As a result, my code no longer compiles.
>Hans> I have looked a little on the skeleton code, and there are two
>Hans> problems with union's and C++:
>Hans> First, if one is using the %union option and C++ types, then a
>Hans> proper C++ compiler should reject that. Now, Bison does not seem
>Hans> to do anything with the types, except putting them in when
>Hans> defined. %union seems to only require that all nonterminals are
>Hans> typed; for that last part, I introduced a %typed option. Thus
>Hans> %union { <body> } should be equivalent to %{ typedef union {
>Hans> <body> } yystype; #define YYSTYPE yystype ...  %} %typed ...
>Hans, I would *really* appreciate if you could keep the threads
>focused on their subject.  I was *not* referring to what you just
>wrote, and I made that *perfectly* clear.
>We all know the other issue.  It's just not the subject.

I really do not see what you are hinting at here, because if the thread is
"Comments in %union processed incorrectly", then the stuff you mention have
nothing to do about that, and if you have a class with non-trivial
constructors, there is no way to combine that with unions, so if you are
aware of it, I do not see why you are mentioning it at all.

  Hans Aberg

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