Re: Fwd: Try to wrap Midnight Commander in Rust

[David Haller <dnh opensuse org>]

Hello,

On Sun, 15 Aug 2021, Yury V. Zaytsev wrote:
> Begin forwarded message:
> > From: Vitold S <vit1251 gmail com>
[..]
> > warning: lib/event/manage.c: In function 'mc_event_group_destroy_value':
> > warning: lib/event/manage.c:52:37: warning: cast between incompatible function types from 'void (*)(void 
> > *)' to 'void (*)(void *, void *)' [-Wcast-function-type]
> > warning:    52 |     g_ptr_array_foreach (callbacks, (GFunc) g_free, NULL);
> > warning:       |                                     ^

Just taking the first warning as an example: this has nothing to do
with mc, this is a glib-2 upstream issue. In e.g. glib-2.68.3 we have
these decls:

glib/garray.h: void g_ptr_array_foreach(GPtrArray        *array,
                                        GFunc             func,
                                        gpointer          user_data);

The 'GFunc func' is the function pointer being cast. Also:

glib/gtypes.h: typedef void  (*GFunc) (gpointer data,
                                       gpointer user_data);

and

glib/gmem.h: void     g_free           (gpointer      mem);

The only way around these conflicting types (that I see) is an (inlined)
wrapper function around g_free.

Actually, I'd just use '-Wno-cast-function-type' or omit the '-Wextra'.

HTH,
-dnh

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