Re: %union with STL

[Hans Aberg]

On 27 May 2009, at 10:32, Vincent Zweije wrote:

> ||  So what does the C++ standard say about it?
>
> "In a union, at most one of the data members can be active at any  
> time,
> that is, the value of at most one of the data members can be stored in
> a union at any time. [...] Each data member is allocated as if it were
> the sole member of a struct."
>
> And for those interested in the problem with the bison union:
>
> "An object of a class with a non-trivial constructor (12.1), a non- 
> trivial
> copy construtor (12.8), a non-trivial destructor (12.4), or a non- 
> trivial
> copy assignment operator (13.5.3, 12.8) cannot be a member of a union,
> nor can an array of such objects."

I saw those, but none of them say anything about pointers - it  
probably follows from the grammar-like rules in 9.2.

> ||  Did you see the post by Vincent?
>
> And I noticed that std::string appears to be used as well, which needs
> a #include <string>. :)

I could not reproduce the compile error. If I include the header  
<string>, I do not need to include <utility>, and if I exclude both or  
<string>, I get different compiler errors. I did not use a full Bison  
generated parser, nor "using namespace std".

  Hans