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From: "Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>
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Subject: Pure Aspect on Library-Level Function
Date: Sat, 6 Feb 2021 22:59:09 +0100
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Given a library-level function in file f.ads

function F (Source : String) return String with Pure;

compiler G has no problem with this. Compiler O rejects it with the error msg

f.ads: Error: line 1 col 48 LRM:K.1(47), The Pure aspect is not allowed for a 
subprogram declaration

which is interesting, since Annex K is not normative. K.1 is Language-Defined 
Aspects, and K.1(47) is

47/3
  Pure
Side effects are avoided in the subprograms of a given package. See 10.2.1.

10.2.1 doesn't mention packages or subprograms, but rather compilation units 
(which subprograms may be), and it also talks about the effect of pragma Pure 
rather than aspect Pure. It does say

"A pragma Pure is used to specify that a library unit is declared pure, namely 
that the Pure aspect of the library unit is True"

which implies that library units have the Pure aspect, and since library units 
can be subprograms, such subprograms have the Pure aspect. It seems reasonable 
to presume that if something has an aspect, that aspect may be named in an 
aspect specification.

So I think the aspect is legal, but I'd like to know what others think.

-- 
Jeff Carter
"I would never want to belong to any club that
would have someone like me for a member."
Annie Hall
41