File gcc15.patch of Package gap

From e080de9a6b37e806dcd7b4814926a1b59b64d2cc Mon Sep 17 00:00:00 2001
From: Jan Engelhardt <jengelh@inai.de>
Date: Wed, 18 Jun 2025 06:07:10 +0200
Subject: [PATCH] Stop using declarators with unspecified arguments
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References: https://github.com/gap-system/gap/pull/6010

GCC 15/-std=c23:

```
src/bool.c:332:22: error: passing argument 1 of 'InitHandlerFunc' from incompatible pointer type [-Wincompatible-pointer-types]
  332 |     InitHandlerFunc( ReturnTrue1, "src/bool.c:ReturnTrue1" );
[   19s] src/calls.h:416:30: note: expected ‘ObjFunc’ {aka ‘struct OpaqueBag * (*)(void)’} but argument is of type ‘struct OpaqueBag * (*)(struct OpaqueBag *, struct OpaqueBag *)’
```

Declarators with unspecified arguments `int f();` got socially
deprecated with C89; since then, one can write `f(void)` for actual
zero-argument functions, and `f(T, ...)` for varargs functions.

C23 finally yanked declarators with unspecified arguments.

Different pointer types may have different size. So you can't have
one pointer type for "all kinds of functions" in plain C. Nor C++ for
that matter; some use of templates/RTTI would be necessary (possibly
hidden in something like std::any, but still).

Or rely on platform-specific extensions, e.g. POSIX>=2001 guarantees
that sizeof(void*) >= sizeof(any function pointer) and that
conversion is meaningful; this is effectively mandated by the
presence of dlsym(). For Windows, sizeof(FARPROC) >= sizeof(afp),
effectively mandated by GetProcAddress().

Fixes: #5857 #6009
---
 src/common.h | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/src/common.h b/src/common.h
index 3932c3020..02818f567 100644
--- a/src/common.h
+++ b/src/common.h
@@ -161,12 +161,7 @@ typedef Bag Obj;
 **
 **  'ObjFunc' is the type of a function returning an object.
 */
-#pragma GCC diagnostic push
-#ifndef __cplusplus
-#pragma GCC diagnostic ignored "-Wstrict-prototypes"
-#endif
-typedef Obj (* ObjFunc) (/*arguments*/);
-#pragma GCC diagnostic pop
+typedef void * ObjFunc;
 
 typedef Obj (* ObjFunc_0ARGS) (Obj self);
 typedef Obj (* ObjFunc_1ARGS) (Obj self, Obj a1);
-- 
2.49.0