[LLVMdev] Union type, is it really used or necessary?

[Erik de Castro Lopo]

Chris Lattner wrote:

> >  a) What is required for them to be accepted back in?
> 
> It needs to work.  When reverted, it was broken in almost all cases.

'It needs work' and 'it was broken' doesn't really give me an
idea of what specifically is required.

Specifically, what I am interested in is using unions within
packed structs to force alignment. Using unions like this was
the easiest and most reliable way of forcing specific alignment.
It made it really easy to calculate offsets in high level code
allowing me to completely ignore whether I was generating code
for 32 or 64 bits.

> >  b) What are the chances of getting them in the 2.8 release?
> 
> Zero.

So a feature, of which a subset was actually working (I know
this because I am using unions successfully in the compiler
I'm working on) in the 2.7 release and was documented on the
web site

    http://llvm.org/releases/2.7/docs/LangRef.html#t_union

just gets yanked?

Are you really trying to tell me that anyone using LLVM in anger
needs to be running SVN HEAD and keep an eye on the mailing list
to make sure that features they use aren't going to get arbitrarily
yanked?

Erik
-- 
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Erik de Castro Lopo
http://www.mega-nerd.com/