* Safe to ignore warnings about function mistaken as primitive?
@ 2022-07-10 8:45 G.B.
2022-07-10 10:19 ` Dmitry A. Kazakov
2022-07-11 4:27 ` Stephen Leake
0 siblings, 2 replies; 4+ messages in thread
From: G.B. @ 2022-07-10 8:45 UTC (permalink / raw)
GNAT warns about primitive operations appearing too late in the text.
In the following example, though, F is not meant to be a primitive
operation of A.Some_Tagged, but instead one of type B.Plain.
Can I ignore the warning?
gcc -gnatl -c rt_warn.ads
GNAT 11.2.0
Copyright 1992-2021, Free Software Foundation, Inc.
cannot generate code for file rt_warn.ads (package spec)
Compiling: rt_warn.ads
Source file time stamp: 2022-07-10 08:34:32
Compiled at: 2022-07-10 10:34:39
1. package Rt_Warn is
2.
3. package A is
4.
5. type Some_Tagged is interface;
6.
7. end A;
8.
9. package B is
10.
11. type Plain is private;
12.
13. function F (Param : A.Some_Tagged) return Plain;
|
>>> warning: declaration of "F" is too late
>>> warning: spec should appear immediately after declaration of "Some_Tagged"
14. function FC (Param : A.Some_Tagged'Class) return Plain;
15. private
16. type Plain is record
17. null;
18. end record;
19. end B;
20.
21. end Rt_Warn;
21 lines: No errors, 2 warnings
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Safe to ignore warnings about function mistaken as primitive?
2022-07-10 8:45 Safe to ignore warnings about function mistaken as primitive? G.B.
@ 2022-07-10 10:19 ` Dmitry A. Kazakov
2022-07-11 4:27 ` Stephen Leake
1 sibling, 0 replies; 4+ messages in thread
From: Dmitry A. Kazakov @ 2022-07-10 10:19 UTC (permalink / raw)
On 2022-07-10 10:45, G.B. wrote:
> GNAT warns about primitive operations appearing too late in the text.
> In the following example, though, F is not meant to be a primitive
> operation of A.Some_Tagged, but instead one of type B.Plain.
>
> Can I ignore the warning?
>
> gcc -gnatl -c rt_warn.ads
>
> GNAT 11.2.0
> Copyright 1992-2021, Free Software Foundation, Inc.
> cannot generate code for file rt_warn.ads (package spec)
>
>
> Compiling: rt_warn.ads
> Source file time stamp: 2022-07-10 08:34:32
> Compiled at: 2022-07-10 10:34:39
>
> 1. package Rt_Warn is
> 2.
> 3. package A is
> 4.
> 5. type Some_Tagged is interface;
> 6.
> 7. end A;
> 8.
> 9. package B is
> 10.
> 11. type Plain is private;
> 12.
> 13. function F (Param : A.Some_Tagged) return Plain;
> |
> >>> warning: declaration of "F" is too late
> >>> warning: spec should appear immediately after declaration
> of "Some_Tagged"
Some_Tagged is an interface, it cannot have implementations anyway.
Should be an error rather than just warning to me.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Safe to ignore warnings about function mistaken as primitive?
2022-07-10 8:45 Safe to ignore warnings about function mistaken as primitive? G.B.
2022-07-10 10:19 ` Dmitry A. Kazakov
@ 2022-07-11 4:27 ` Stephen Leake
2022-07-11 13:17 ` G.B.
1 sibling, 1 reply; 4+ messages in thread
From: Stephen Leake @ 2022-07-11 4:27 UTC (permalink / raw)
"G.B." <bauhaus@notmyhomepage.invalid> writes:
> GNAT warns about primitive operations appearing too late in the text.
> In the following example, though, F is not meant to be a primitive
> operation of A.Some_Tagged, but instead one of type B.Plain.
>
> Can I ignore the warning?
It's best to never ignore warnings, but instead fix them. Even if the
only way to "fix" it is to add "pragma Warnings (Off ...)"; that at
least tells the reader you have considered the warning.
Since B.F is declared in a sibling package, it cannot a primitive of
A.Some_Tagged, so the error message is wrong.
Since A.Some_Tagged is an interface, you can only declare abstract
primitive subprograms for it. So I suspect GNAT knows there's an error, but is
giving a confusing error message.
How are you intending F to be different from FC?
--
-- Stephe
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Safe to ignore warnings about function mistaken as primitive?
2022-07-11 4:27 ` Stephen Leake
@ 2022-07-11 13:17 ` G.B.
0 siblings, 0 replies; 4+ messages in thread
From: G.B. @ 2022-07-11 13:17 UTC (permalink / raw)
On 11.07.22 06:27, Stephen Leake wrote:
> Since B.F is declared in a sibling package, it cannot a primitive of
> A.Some_Tagged, so the error message is wrong.
>
> Since A.Some_Tagged is an interface, you can only declare abstract
> primitive subprograms for it. So I suspect GNAT knows there's an error, but is
> giving a confusing error message.
It seems possible to write programs declaring B.F (Param : A.Some_Tagged)...,
but hardly one that isn't pointless! Adding "in out" to the
function's Param allows 'Access using 'Class renames Ref'(Param'Access).all
and then 'Unchecked_Access---so twisted I shan't repeat it here.
Adding (... : access A.Some_Tagged) works a lot better (of course <:-|),
and still has the warning.
But, GNAT is right, I think!
> How are you intending F to be different from FC?
The first F was a bad choice, I guess; I had wanted to exclude a potentially
larger interface. FC was the beginning of dropping F.
FC now takes an access to class-wide.
With Op1 added to the interface of Some_Tagged,
package B is
type Plain(<>) is private;
function FC (Param : access A.Some_Tagged'Class) return Plain;
procedure G (Item : in out Plain; Param : in Character);
-- Calls Op1 of Item.Client
private
type Plain (Client : access A.Some_Tagged'Class) is record
null;
end record;
end B;
No F, no warning.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-07-11 13:17 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-07-10 8:45 Safe to ignore warnings about function mistaken as primitive? G.B.
2022-07-10 10:19 ` Dmitry A. Kazakov
2022-07-11 4:27 ` Stephen Leake
2022-07-11 13:17 ` G.B.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox