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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: Abstract Syntax Tree for C programs
Date: Fri, 07 Jun 2019 09:54:35 -0700
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Bart <bc@freeuk.com> writes:
[...]
> Sometimes it's more convenient to do without the unions (which can run 
> foul of various C constraints about the order in which members can be 
> read and written).
>
> A simple example is of an array which can represent byte-code (or it 
> could work for other kinds of processing), where the first element is 
> pointer to a function that handles a particular operation, followed by 0 
> or more object pointers that are consumed by the function, and that 
> point to any operands or arguments.
>
> And then those are followed by the next function pointer, etc. The 
> simplest representation is a void* array.

Wouldn't an array of int be even simpler?

What's that you say?  You can't portably store a function pointer value
in an int object?  Do tell.

An array of unions isn't quite as simple, but it has the considerable
virtue of being valid and portable C.  As a bonus, it works around
the gcc bug we've discussed in this thread.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */