Re: %union errors

[Laurence Finston]

On Fri, 5 Dec 2008, Benny Hardage wrote:

> %union
> {
>         int intVal;
>         bool boolVal;
>         char* strVal;
>         std::list<const Variable::Qualifier*>* qList;
>         Variable* var;
>         UnaryOperation* uop;
>         BinaryOperation* binop;
>         Expression* expr;
>         DataLiteral* datalit;
> }
> 

I had a problem trying to use types defined in the STL in the `%union'.  
I don't remember the details, but I believe it involved types where the
size isn't known at compile-time not being permitted in unions.  I think 
there was something about constructors as well.  I believe this is 
documented in the section about unions in Stroustrup's _The C++ Programming 
Language_.  At any rate, I couldn't get it to work.

My unions for Bison usually contain an `int', a `float', a `char' vector, and
a `void*' for everything else.  `void*' as `YYSTYPE' would do the trick, 
but I find it convenient to have semantic values of the other types
without having to use casts.

Laurence Finston

On Fri, 5 Dec 2008, Benny Hardage wrote:

> Hello,
> 
> I'm receiving the following errors when I compile:
> 
> In file included from compiler.l:17:
> parser.y:27: error: ISO C++ forbids declaration of 'list' with no type
> parser.y:27: error: invalid use of '::'
> parser.y:27: error: expected ';' before '<' token
> parser.y:28: error: ISO C++ forbids declaration of 'Variable' with no type
> parser.y:28: error: expected ';' before '*' token
> parser.y:29: error: ISO C++ forbids declaration of 'UnaryOperation' with no 
> type
> parser.y:29: error: expected ';' before '*' token
> parser.y:30: error: ISO C++ forbids declaration of 'BinaryOperation'
> with no type
> parser.y:30: error: expected ';' before '*' token
> parser.y:31: error: ISO C++ forbids declaration of 'Expression' with no type
> parser.y:31: error: expected ';' before '*' token
> parser.y:32: error: ISO C++ forbids declaration of 'DataLiteral' with no type
> parser.y:32: error: expected ';' before '*' token
> 
> I've seen a fairly old thread that attempted to address this issue,
> saying that my include files might not be in the right order, but the
> top of my file looks like the following:
> 
> %error-verbose
> 
> %{
> 
> int yylex();
> 
> #include <iostream>
> #include "expressions.hpp"
> #include "statements.hpp"
> 
> extern bool outputTokens;
> extern bool outputParser;
> 
> void yyerror( char* msg )
> {
>         std::cerr << msg << std::endl;
> }
> 
> %}
> 
> %union
> {
>         int intVal;
>         bool boolVal;
>         char* strVal;
>         std::list<const Variable::Qualifier*>* qList;
>         Variable* var;
>         UnaryOperation* uop;
>         BinaryOperation* binop;
>         Expression* expr;
>         DataLiteral* datalit;
> }
> 
> expressions.hpp contains the datatypes in question.
> 
> I was wondering if someone might let me know what I was doing wrong.
> 
> Thanks,
> B.J.
> 
> 
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