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From: Julia Lawall <julia.lawall@inria.fr>
To: Markus Elfring <Markus.Elfring@web.de>
Cc: Coccinelle <cocci@systeme.lip6.fr>
Subject: Re: [Cocci] Adjusting some calls according to pass-through functions
Date: Sun, 29 Nov 2020 12:54:32 +0100 (CET)
Message-ID: <alpine.DEB.2.22.394.2011291250490.2671@hadrien> (raw)
In-Reply-To: <0148bab2-6148-e403-985d-df2e7cade490@web.de>


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On Sun, 29 Nov 2020, Markus Elfring wrote:

> > I stumble on further software challenges if I would like to make the simple
> > transformation approach a bit more variable on the number of surrounding parameters.
>
> It looked promising that another SmPL script variant gets also successfully parsed
> by the current Coccinelle software.
>
>
> @Replacement@
> expression action, input1, input2, input3, target;
> identifier gs;
> @@
> -\( g_string_assign@gs \| g_string_append@gs \| g_string_append_c@gs \) (target, input1);
>  action (
> +        gs (
>              target
> +            , input1)
>              ,
> (            input2, input3
> |            input2
> )       );

I find this way of writing disjunctions really unreadable.  You are saving
some precious whitespace characters at the cost of making any distinction
between what is obligatory and what is optional.

>
> But another test run shows opportunities for further clarification of
> the following software behaviour.
>
>
> elfring@Sonne:~/Projekte/Gnome/Evolution-Data-Server/lokal> spatch --smpl-spacing --max-width 120 src/addressbook/libedata-book/e-book-sqlite.c ~/Projekte/Gnome/use_string_action_return_pointer8.cocci
> …
> previous modification:
> MINUS
>
> According to environment 2:
>    Replacement.input1 -> ' '
>
>    Replacement.gs -> id g_string_append_c
>
>
> current modification:
>
>   <<< gs(
> CONTEXT
>   >>> , input1)
>
>
> According to environment 2:
>    Replacement.input1 -> info->name
>
>    Replacement.gs -> id g_string_append
>
>
> Replacement: already tagged token:
> C code context
> File "src/addressbook/libedata-book/e-book-sqlite.c", line 1909, column 20, charpos = 53094
>   around = 'string',
>   whole content = 	g_string_append_c (string, ' ');
>
>
> The implementation of a function like “format_column_declaration” contains
> the following statements.
> https://gitlab.gnome.org/GNOME/evolution-data-server/-/blob/3de7ea5fdb5d5db4a097a4d888d77bd2778c1c30/src/addressbook/libedata-book/e-book-sqlite.c#L1898
>
> 	g_string_append (string, info->name);
> 	g_string_append_c (string, ' ');
>
> 	g_string_append (string, info->type);
>
> 	if (info->extra) {
> 		g_string_append_c (string, ' ');
> 		g_string_append (string, info->extra);
> 	}

The rule matches for example on the first line and on the second line.
The match on the first line makes a change in the second line.  The match
on the second line removes the second line.  This is a conflict, as
reported.

The problem would be solved in this case by making two separate rules.

julia

>
>
> I imagine that such source code can be transformed into the following variant.
>
> 	g_string_append (g_string_append_c (g_string_append (string, info->name), ' '), info->type);
>
> 	if (info->extra)
> 		g_string_append (g_string_append_c (string, ' '), info->extra);
>
>
> Do you find any extensions interesting for such a code refactoring?
>
> Regards,
> Markus
>

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Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-28 17:21 [Cocci] Checking the influence of an omitted semicolon on a code adjustment Markus Elfring
2020-11-28 17:45 ` Julia Lawall
2020-11-28 18:56   ` Markus Elfring
2020-11-28 19:00     ` Julia Lawall
2020-11-28 19:11       ` Markus Elfring
2020-11-28 19:49         ` Julia Lawall
2020-11-28 20:04           ` Markus Elfring
     [not found]             ` <0148bab2-6148-e403-985d-df2e7cade490@web.de>
2020-11-29 11:54               ` Julia Lawall [this message]
     [not found]                 ` <3b134eb3-7ccf-454c-3266-64cfaec5a307@web.de>
2020-11-29 12:25                   ` [Cocci] Adjusting some calls according to pass-through functions Julia Lawall
     [not found]                     ` <978f08c3-21ed-d434-d2ef-163335ae990e@web.de>
2020-11-29 12:52                       ` Julia Lawall
     [not found]                         ` <1dc8f835-11b1-0ec0-8ba4-45cffdf13465@web.de>
2020-11-29 13:47                           ` Julia Lawall
     [not found]                     ` <cb266001-ed38-da76-389c-5a7bf7f59e9e@web.de>
2020-11-29 13:43                       ` Julia Lawall
     [not found]                         ` <79d4245d-6f34-7b8d-d632-99afcc1d228a@web.de>
2020-11-29 14:44                           ` Julia Lawall
     [not found]                             ` <beeb673b-65b5-fdef-f300-c86a4bd0abc7@web.de>
2020-11-29 15:18                               ` Julia Lawall
     [not found]                                 ` <cf0e2d68-d76b-5892-b97e-36a270732028@web.de>
2020-11-29 15:52                                   ` Julia Lawall
     [not found]                                     ` <b548f18b-2fa7-1fcf-5bbb-3011d8a270e5@web.de>
2020-11-29 16:24                                       ` Julia Lawall

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