Re: C-style 'union' in Ada?

[Ted Dennison<dennison@telepath.com>]

In article <3B7D4894.C342A35C@boeing.com>, Jeffrey Carter says...
>
>Unchecked_Conversion is allowed to return its result "by reference".
>This allows a good compiler to avoid assignment when possible.

Really? I wouldn't think that's possible, since the source and target are going
to be distinct objects with discinct storage addresses. Clearly the data isn't
getting from one to the other without a copy happening somewhere.

If you are talking about doing something like accessing a field after an
unchecked_conversion, eg. doing a: 
if Convert_To_String (Big_Hairy_Record)(1) = 'a' then ...

then I could see it. However, I know the one time I checked into it (on the DEC
Ada83 compiler), it would put a full copy on the stack even in this instance.
Does anyone know what some of the modern compilers do?

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