From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Lower bounds of Strings
Date: Tue, 5 Jan 2021 14:40:19 +0100 [thread overview]
Message-ID: <rt1q81$11j9$1@gioia.aioe.org> (raw)
In-Reply-To: rt1m8f$ukj$1@dont-email.me
On 2021-01-05 13:32, Jeffrey R. Carter wrote:
> On 1/5/21 12:57 PM, Dmitry A. Kazakov wrote:
>>
>> This is a constraint, a meaningless and dangerous one:
>>
>> procedure Foo (X : Mono_String);
>> S : String := "abcdefgh";
>> begin
>> Foo (S (2..S'Last)); -- Boom! Constraint_Error
>
> Surely the slice would slide, as it does in
>
> with Ada.Text_IO;
>
> procedure Slider is
> subtype S7 is String (1 .. 7);
>
> procedure Foo (X : in S7);
>
> procedure Foo (X : in S7) is
> -- Empty
> begin -- Foo
> Ada.Text_IO.Put (Item => X (7) );
> Ada.Text_IO.New_Line;
> end Foo;
>
> S : constant String := "abcdefgh";
> begin -- Slider
> Foo (X => S (2 .. 8) );
> end Slider;
>
> ~/Code$ gnatmake -gnatan -gnato2 -O2 -fstack-check slider.adb
> x86_64-linux-gnu-gcc-9 -c -gnatan -gnato2 -O2 -fstack-check slider.adb
> x86_64-linux-gnu-gnatbind-9 -x slider.ali
> x86_64-linux-gnu-gnatlink-9 slider.ali -O2 -fstack-check
> ~/Code$ ./slider
> h
Yes, but here S7 is definite, it is a quite different case. Sliding
indefinite subtypes without copies, with access types allowed?
And even with definite subtypes it is broken:
with Ada.Text_IO; use Ada.Text_IO;
procedure Main is
subtype S7 is String (1..7);
S : constant String := "abcdefgh";
V : S7 renames S (2..8);
begin
Put_Line ("Is it broken? " & Boolean'Image (S (7) = V (7)));
end Main;
This will print: Is it broken? TRUE
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2021-01-05 13:40 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-05 11:04 Lower bounds of Strings Stephen Davies
2021-01-05 11:57 ` Dmitry A. Kazakov
2021-01-05 12:32 ` Jeffrey R. Carter
2021-01-05 13:40 ` Dmitry A. Kazakov [this message]
2021-01-05 14:31 ` Stephen Davies
2021-01-05 17:24 ` Stephen Davies
2021-01-05 18:28 ` Jeffrey R. Carter
2021-01-05 21:02 ` Stephen Davies
2021-01-07 10:38 ` Stephen Davies
2021-01-07 21:39 ` Randy Brukardt
2021-01-07 22:38 ` Stephen Davies
2021-01-05 12:24 ` Luke A. Guest
2021-01-05 12:49 ` Simon Wright
2021-01-05 12:51 ` Jeffrey R. Carter
2021-01-06 3:08 ` Randy Brukardt
2021-01-06 9:13 ` Dmitry A. Kazakov
2021-01-07 0:17 ` Randy Brukardt
2021-01-07 9:57 ` Dmitry A. Kazakov
2021-01-07 22:03 ` Randy Brukardt
2021-01-08 9:04 ` Dmitry A. Kazakov
2021-01-08 17:23 ` Shark8
2021-01-08 20:19 ` Dmitry A. Kazakov
2021-01-09 2:18 ` Randy Brukardt
2021-01-09 10:53 ` Dmitry A. Kazakov
2021-01-12 8:19 ` Randy Brukardt
2021-01-12 9:37 ` Dmitry A. Kazakov
2021-01-09 2:31 ` Randy Brukardt
2021-01-09 14:52 ` Why UTF-8 (was Re: Lower bounds of Strings) Jeffrey R. Carter
2021-01-09 18:08 ` Dmitry A. Kazakov
2021-01-12 7:58 ` Randy Brukardt
2021-01-11 21:35 ` Lower bounds of Strings Shark8
2021-01-12 8:12 ` Randy Brukardt
2021-01-12 20:51 ` Shark8
2021-01-12 22:56 ` Randy Brukardt
2021-01-13 12:00 ` Dmitry A. Kazakov
2021-01-13 13:27 ` AdaMagica
2021-01-13 13:53 ` Dmitry A. Kazakov
2021-01-13 14:08 ` Jeffrey R. Carter
2021-01-14 11:38 ` AdaMagica
2021-01-14 12:27 ` Dmitry A. Kazakov
2021-01-14 13:31 ` AdaMagica
2021-01-14 14:02 ` Jeffrey R. Carter
2021-01-14 14:34 ` Dmitry A. Kazakov
2021-01-14 15:28 ` Shark8
2021-01-14 15:41 ` Dmitry A. Kazakov
2021-01-19 21:02 ` G.B.
2021-01-19 22:27 ` Dmitry A. Kazakov
2021-01-20 20:10 ` G.B.
2021-01-20 20:25 ` Dmitry A. Kazakov
2021-01-15 10:24 ` Stephen Davies
2021-01-15 11:41 ` J-P. Rosen
2021-01-15 17:35 ` Stephen Davies
2021-01-15 19:36 ` Egil H H
2021-01-16 12:57 ` Stephen Davies
2021-01-17 14:10 ` Stephen Davies
2021-01-19 5:48 ` Randy Brukardt
2021-01-19 6:13 ` Gautier write-only address
2021-01-15 11:48 ` Jeffrey R. Carter
2021-01-15 13:34 ` Dmitry A. Kazakov
2021-01-15 13:56 ` Stephen Davies
2021-01-15 15:12 ` Jeffrey R. Carter
2021-01-15 17:22 ` Stephen Davies
2021-01-15 21:10 ` Jeffrey R. Carter
2021-01-15 14:00 ` Stephen Davies
2021-01-16 9:30 ` G.B.
2021-01-16 13:13 ` Stephen Davies
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