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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Formal Subprogram Access
Date: Tue, 13 Feb 2018 12:24:08 +0000
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Date: 2018-02-13T12:24:08+00:00
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"Randy Brukardt" <randy@rrsoftware.com> writes:

> There's no such rule in the RM. As Christoph noted, a generic formal
> subprogram has convention Ada, 'Access is allowed. If you pass an
> attribute to it, you have to wrap it in a real subprogram for this
> reason. (There is a lot of code specifically to do this in Janus/Ada,
> it probably never has been tested outside of a single ACATS test -- I
> don't think anyone ever has had a reason to pass an attribute like
> Succ as a formal subprogram.)

In GNAT, I've passed 'Image, 'Value as actuals for corresponding formal
subprograms.

   generic
      type Checked_Type is private;
      Checked_Type_Name : String;
      with function "=" (L, R : Checked_Type) return Boolean is <>;
      with function Value (S : String) return Checked_Type is <>;
      with function Image (V : Checked_Type) return String is <>;
   package Check_Passed_Value is

Which ACATS test should have caught that (or any other attribute, of
course)?

I see that the GCC-based tests that I've been working on at
https://github.com/simonjwright/ACATS wouldn't necessarily catch all the
errors expected in the B (and L?) tests: for example, BC70009 reports 4
compilation errors, which counts as a success because of course B tests
are expected to fail, but doesn't check that all the expected errors
have in fact been caught. (In this case, 4 was correct.) I should check
the grading tool, though I'm not sure that complete conformance checks
are justified in this context - it's more to ensure that some feature
hasn't been broken.