https://bugs.gentoo.org/883069
https://src.fedoraproject.org/rpms/dia/raw/rawhide/f/dia-0.97.3-const-ft_vector.patch
https://src.fedoraproject.org/rpms/dia/blob/rawhide/f/dia-0.97.3-g_test_add_data_func_1.patch
https://src.fedoraproject.org/rpms/dia/blob/rawhide/f/dia-0.97.3-g_test_add_data_func_2.patch
https://src.fedoraproject.org/rpms/dia/blob/rawhide/f/dia-0.97.3-get_data_size.patch

From e5557aa1d396bc3ca80240f7b5c0a1831a5cf209 Mon Sep 17 00:00:00 2001
From: Hans Breuer <hans@breuer.org>
Date: Sat, 4 May 2013 15:20:15 +0200
Subject: [PATCH] [warningectomy] initialization from incompatible pointer type

FT_Outline_Funcs take const FT_Vector* nowadays.
--- a/plug-ins/postscript/diapsft2renderer.c
+++ b/plug-ins/postscript/diapsft2renderer.c
@@ -61,16 +61,16 @@ void draw_bezier_outline(DiaPsRenderer *renderer,
 			 double pos_y
 			 );
 /* Countour traveling functions */
-static int paps_move_to( FT_Vector* to,
+static int paps_move_to( const FT_Vector* to,
 			 void *user_data);
-static int paps_line_to( FT_Vector*  to,
+static int paps_line_to( const FT_Vector*  to,
 			 void *user_data);
-static int paps_conic_to( FT_Vector*  control,
-			  FT_Vector*  to,
+static int paps_conic_to( const FT_Vector*  control,
+			  const FT_Vector*  to,
 			  void *user_data);
-static int paps_cubic_to( FT_Vector*  control1,
-			  FT_Vector*  control2,
-			  FT_Vector*  to,
+static int paps_cubic_to( const FT_Vector*  control1,
+			  const FT_Vector*  control2,
+			  const FT_Vector*  to,
 			  void *user_data);
 
 static void dia_ps_ft2_renderer_class_init (DiaPsFt2RendererClass *klass);
@@ -111,7 +111,7 @@ set_font(DiaRenderer *self, DiaFont *font, real height)
 /*======================================================================
   outline traversing functions.
   ----------------------------------------------------------------------*/
-static int paps_move_to( FT_Vector* to,
+static int paps_move_to( const FT_Vector* to,
 			 void *user_data)
 {
   OutlineInfo *outline_info = (OutlineInfo*)user_data;
@@ -121,7 +121,7 @@ static int paps_move_to( FT_Vector* to,
   return 0;
 }
 
-static int paps_line_to( FT_Vector*  to,
+static int paps_line_to( const FT_Vector*  to,
 			 void *user_data)
 {
   OutlineInfo *outline_info = (OutlineInfo*)user_data;
@@ -131,8 +131,8 @@ static int paps_line_to( FT_Vector*  to,
   return 0;
 }
 
-static int paps_conic_to( FT_Vector*  control,
-			  FT_Vector*  to,
+static int paps_conic_to( const FT_Vector*  control,
+			  const FT_Vector*  to,
 			  void *user_data)
 {
   OutlineInfo *outline_info = (OutlineInfo*)user_data;
@@ -144,9 +144,9 @@ static int paps_conic_to( FT_Vector*  control,
   return 0;
 }
 
-static int paps_cubic_to( FT_Vector*  control1,
-			  FT_Vector*  control2,
-			  FT_Vector*  to,
+static int paps_cubic_to( const FT_Vector*  control1,
+			  const FT_Vector*  control2,
+			  const FT_Vector*  to,
 			  void *user_data)
 {
   OutlineInfo *outline_info = (OutlineInfo*)user_data;
-- 
GitLab

From caddfcab250fe677ecf294fad835b71e6b10cf26 Mon Sep 17 00:00:00 2001
From: Hans Breuer <hans@breuer.org>
Date: Fri, 3 Oct 2014 22:26:36 +0200
Subject: [PATCH] [warningectomy] incompatible pointer types passing ...

test-boundingbox.c:152:58: warning: incompatible pointer types passing 'void (const struct _TestBeziers *)' to parameter of type 'GTestDataFunc' (aka 'void (*)(gconstpointer)') [-Wincompatible-pointer-types]
      g_test_add_data_func (testpath, &_test_beziers[i], _check_one_bezier);
                                                         ^~~~~~~~~~~~~~~~~
test-svg.c:117:55: warning: incompatible pointer types passing 'void (const PathData *)' to parameter of type 'GTestDataFunc' (aka 'void (*)(gconstpointer)') [-Wincompatible-pointer-types]
      g_test_add_data_func (testpath, &_test_path[i], _check_one_path);
                                                      ^~~~~~~~~~~~~~~
--- a/tests/test-boundingbox.c
+++ b/tests/test-boundingbox.c
@@ -132,8 +132,9 @@ static struct _TestBeziers {
 #undef BEZ
 
 static void
-_check_one_bezier (const struct _TestBeziers *test)
+_check_one_bezier (gconstpointer p)
 {
+  const struct _TestBeziers *test = p;
   Rectangle rect;
   PolyBBExtras extra = {0, T*.7, T*.7, T*.7, 0 };
   
Backport from https://gitlab.gnome.org/GNOME/dia/-/commit/9c481f649414190bf8d6741cbca1777e9766756b

--- a/tests/test-objects.c
+++ b/tests/test-objects.c.g_test_add_data_func_2
@@ -39,8 +39,9 @@
 int num_objects = 0;
 
 static void
-_test_creation (const DiaObjectType *type)
+_test_creation (gconstpointer user_data)
 {
+  const DiaObjectType *type = (const DiaObjectType *)user_data;
   int i;
   Handle *h1 = NULL, *h2 = NULL;
   Point point = {0, 0};
@@ -112,8 +113,9 @@
 }
 
 static void
-_test_copy (const DiaObjectType *type)
+_test_copy (gconstpointer user_data)
 {
+  const DiaObjectType *type = (const DiaObjectType *)user_data;
   Handle *h1 = NULL, *h2 = NULL;
   Point from = {0, 0};
   DiaObject *oc, *o = type->ops->create (&from, type->default_user_data, &h1, &h2);
@@ -172,8 +174,9 @@
 }
 
 static void
-_test_movement (const DiaObjectType *type)
+_test_movement (gconstpointer user_data)
 {
+  const DiaObjectType *type = (const DiaObjectType *)user_data;
   Handle *h1 = NULL, *h2 = NULL;
   Point from = {0, 0};
   DiaObject *o = type->ops->create (&from, type->default_user_data, &h1, &h2);
@@ -215,8 +218,9 @@
 }
 
 static void
-_test_change (const DiaObjectType *type)
+_test_change (gconstpointer user_data)
 {
+  const DiaObjectType *type = (const DiaObjectType *)user_data;
   Handle *h1 = NULL, *h2 = NULL;
   Point from = {0, 0};
   DiaObject *o = type->ops->create (&from, type->default_user_data, &h1, &h2);

Backport from https://gitlab.gnome.org/GNOME/dia/-/commit/f57ea2685034ddbafc19f35d9b525a12283d7c24

--- a/lib/prop_geomtypes.c
+++ b/lib/prop_geomtypes.c.get_data_size
@@ -129,9 +129,10 @@
 }
 
 static int 
-realprop_get_data_size(RealProperty *prop)
+realprop_get_data_size(void)
 {
-  return sizeof (prop->real_data);
+  RealProperty prop;
+  return sizeof (prop.real_data);
 }
 
 static const PropertyOps realprop_ops = {
@@ -242,9 +243,10 @@
 }
 
 static int 
-lengthprop_get_data_size(LengthProperty *prop)
+lengthprop_get_data_size(void)
 {
-  return sizeof (prop->length_data);
+  LengthProperty prop;
+  return sizeof (prop.length_data);
 }
 
 static const PropertyOps lengthprop_ops = {
@@ -358,9 +360,10 @@
 }
 
 static int 
-fontsizeprop_get_data_size(FontsizeProperty *prop)
+fontsizeprop_get_data_size(void)
 {
-  return sizeof (prop->fontsize_data);
+  FontsizeProperty prop;
+  return sizeof (prop.fontsize_data);
 }
 
 static const PropertyOps fontsizeprop_ops = {
--- a/lib/prop_inttypes.c
+++ b/lib/prop_inttypes.c.get_data_size
@@ -122,9 +122,10 @@
 }
 
 static int 
-charprop_get_data_size(CharProperty *prop)
+charprop_get_data_size(void)
 {
-  return sizeof (prop->char_data);
+  CharProperty prop;
+  return sizeof (prop.char_data);
 }
 
 
@@ -229,9 +230,10 @@
 }
 
 static int 
-boolprop_get_data_size(BoolProperty *prop)
+boolprop_get_data_size(void)
 {
-  return sizeof (prop->bool_data);
+  BoolProperty prop;
+  return sizeof (prop.bool_data);
 }
 
 
@@ -339,9 +341,10 @@
 }
 
 static int 
-intprop_get_data_size(IntProperty *prop)
+intprop_get_data_size(void)
 {
-  return sizeof (prop->int_data);
+  IntProperty prop;
+  return sizeof (prop.int_data);
 }
 
 static const PropertyOps intprop_ops = {
--- a/lib/prop_text.c
+++ b/lib/prop_text.c.get_data_size
@@ -208,9 +208,10 @@
 }
 
 static int 
-stringprop_get_data_size(StringProperty *prop)
+stringprop_get_data_size(void)
 {
-  return sizeof (prop->string_data); /* only the pointer */
+  StringProperty prop;
+  return sizeof (prop.string_data); /* only the pointer */
 }
 
 static StringListProperty *
--- a/lib/properties.h
+++ b/lib/properties.h.get_data_size
@@ -116,7 +116,7 @@
                                          void *base, guint offset, guint offset2);
 typedef void (*PropertyType_SetFromOffset)(Property *prop,
                                          void *base, guint offset, guint offset2);
-typedef int (*PropertyType_GetDataSize)(Property *prop);
+typedef int (*PropertyType_GetDataSize)(void);
 
 
 struct _PropertyOps {
--- a/objects/custom/custom_object.c
+++ b/objects/custom/custom_object.c.get_data_size
@@ -372,14 +372,7 @@
       info->prop_offsets[i].name = info->props[i].name;
       info->prop_offsets[i].type = info->props[i].type;
       info->prop_offsets[i].offset = offs;
-      /* FIXME:
-	 custom_object.c:328: warning: passing arg 1 of pointer to function 
-	 from incompatible pointer type
-	 We don't have a Property* here so there is not much we can do about.
-	 Maybe it even works cause the sizeof() in *_get_data_size can be
-	 calculated at compile time. Anyway, a mess ;) --hb
-      */
-      size = info->props[i].ops->get_data_size (&info->props[i]);
+      size = info->props[i].ops->get_data_size ();
       info->ext_attr_size += size;
       offs += size;
     }