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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Recommendation of safe subset of Ada to use?
Date: Sun, 6 May 2018 11:45:53 +0300
Organization: Tidorum Ltd
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Xref: reader02.eternal-september.org comp.lang.ada:52033
Date: 2018-05-06T11:45:53+03:00
List-Id: <comp.lang.ada>

On 18-05-06 10:43 , Jeffrey R. Carter wrote:
> On 05/05/2018 11:32 PM, gorgelo@hotmail.com wrote:
>>> with Ada.Text_IO; use Ada.Text_IO;
>>>
>>> procedure jdoodle is
>>>       type Integer_Access is access all Integer;
>>>              function Inner(Value : aliased in out Integer) return
>>> Integer_Access is
>>>       begin
>>>           return Value'Access;
>>>       end Inner;
>>>              function Outer return Integer_Access is
>>>           Value : aliased Integer := 0;
>>>       begin
>>>           return Inner(Value);
>>>       end Outer;
>>>              Ptr : Integer_Access := Outer;  -- !!! Dangling reference
>>> begin
>>>       Put_Line("Hello World");
>>> end jdoodle;
>
> This seems to violate ARM 3.10.2(29): the accessibility level of Value
> (the object passed by reference to Inner) is deeper than that of the
> access type Integer_Access. I cannot find an exception to this for
> aliased parameters.

My GNAT complains:

    > gcc -c -g -gnat12 jdoodle.adb
    jdoodle.adb:8:16: non-local pointer cannot point to local object
    gnatmake: "jdoodle.adb" compilation error

However, this is GNAT GPL 2012 (don't ask me why I still use this...)

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .