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From: Florian Weimer <fw@deneb.cygnus.argh.org>
Subject: Re: What is wrong here? (Generic and controlled types)
Date: 2000/04/03
Message-ID: <873dp3hv8x.fsf@deneb.cygnus.argh.org>#1/1
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Reply-To: Florian Weimer <fw-usenet@deneb.cygnus.argh.org>
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Date: 2000-04-03T18:53:02+00:00
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Robert Dewar <robert_dewar@my-deja.com> writes:

|    29.    package Real_Vectors is new Generic_Vectors(Real, Index, Zero);
|           |
|        >>> instantiation error at generic_vectors.ads:23
|        >>> controlled type must be declared at the library level
|        >>> instantiation error at generic_vectors.ads:75
|        >>> controlled type must be declared at the library level

> P.S. it is hard to see how the GNAT message could be any
> clearer, suggestions welcome!

I didn't understand this message, either.  AFAIK, the term "library
level" is not mentioned in Cohen's book -- the one I used (at least,
it's not listed in the index).  The RM definition is easy to find, but
it's not very easy to understand (you must already know the concept of
"accessibility level").  Therefore, I think a message like "controlled
type cannot be declared locally" is more helpful, although it gives
less information (it doesn't say explicitly how to correct this error,
but the original message does).