Hi John,
the relevant warning without the change is here:
../pspp/src/ui/gui/psppire-acr.c: In function ‘on_change_button_clicked’:
../pspp/src/ui/gui/psppire-acr.c:186:22: warning: cast between incompatible
function types from ‘void (*)(GtkTreePath *)’ {aka ‘void (*)(struct
_GtkTreePath *)’} to ‘void (*)(void *, void *)’ [-Wcast-function-type]
g_list_foreach (l, (GFunc) gtk_tree_path_free, NULL);
You can see the full build log here:
http://caeis.etech.fh-augsburg.de:8010/#/builders/4/builds/26
On debian-buster the compiler is gcc8 while on sid the compiler is gcc10.
GFunc is defined with two parameters:
https://developer.gnome.org/glib/stable/glib-Doubly-Linked-Lists.html#GFunc
while gtk_tree_path_free has only one:
https://developer.gnome.org/gtk3/stable/GtkTreeModel.html#gtk-tree-path-free
I guess it is the same behaviour that resulted in this macro
https://developer.gnome.org/glib/stable/glib-The-Main-Event-Loop.html#G-SOURCE-FUNC:CAPS
A discussion about this check is here:
https://gitlab.gnome.org/GNOME/gnome-terminal/-/issues/96
resulting in this cast. Root cause seems to be that the behaviour for different
number of arguments is undefined.
http://c0x.coding-guidelines.com/6.5.2.2.html
The clang compiler version 9 does not issue this warning.
Fritz
> Am 25.08.2020 um 07:00 schrieb John Darrington <j...@darrington.wattle.id.au>:
>
> I don't understand this commit, and I think it just makes the code
> harder to read:
>
>
> commit ceaed4a17cb3b0a14c89f10b72a636f94af97e7a
> Author: Friedrich Beckmann <friedrich.beckm...@gmx.de>
> Date: Mon Aug 24 11:19:33 2020 +0200
>
> Warnings: function type cast for g_list_foreach
>
> I added a cast for the functions used in g_list_foreach. Without
> the cast, the warning
> warning: cast between incompatible function types
> is reported.
>
> diff --git a/src/ui/gui/dialog-common.c b/src/ui/gui/dialog-common.c
> index f167034b1..1b29c4a3b 100644
> --- a/src/ui/gui/dialog-common.c
> +++ b/src/ui/gui/dialog-common.c
> @@ -112,7 +112,7 @@ homogeneous_types (GtkWidget *source, GtkWidget *dest)
> have_type = true;
> }
>
> - g_list_foreach (list, (GFunc) gtk_tree_path_free, NULL);
> + g_list_foreach (list, (GFunc) (void (*)(void)) gtk_tree_path_free,
> NULL);
>
>
> gtk_tree_path_free is already cast to GFunc, so what good does it do to first
> cast it to something else, and _then_ to GFunc without using it? You say
> that
> something is reporting this as a "cast between incompatible types" - That is
> what casts are for - to make incompatible types compatible.
>
> Before, we had:
>
> (void (*) (GtkTreePath *) -> (void (*) (void *, void *))
>
> Now we have:
>
> (void (*) (GtkTreePath *) -> (void (*) (void)) -> (void (*) (void *, void
> *))
>
> What good does the intermediate cast do? Which tool is issuing a warning?
>
> J'
>
>
