build: Don't turn off critical warnings

-Wint-conversion is important because it checks casts from ints to
pointers.

-Wdiscarded-qualifiers is important to catch cases where we don't
strings when we should.

gdk/broadway/broadway-server.c

@@ -901,10 +901,10 @@ map_named_shm (char *name, gsize size)
 #endif
 }
 
-static char *
-parse_line (char *line, char *key)
+static const char *
+parse_line (const char *line, const char *key)
 {
-  char *p;
+  const char *p;
 
   if (!g_str_has_prefix (line, key))
     return NULL;
@@ -970,15 +970,15 @@ static void
 start_input (HttpRequest *request)
 {
   char **lines;
-  char *p;
+  const char *p;
   int i;
   char *res;
-  char *origin, *host;
+  const char *origin, *host;
   BroadwayInput *input;
   const void *data_buffer;
   gsize data_buffer_size;
   GInputStream *in;
-  char *key;
+  const char *key;
   GSocket *socket;
   int flag = 1;
 

gdk/broadway/broadwayd.c

@@ -421,7 +421,7 @@ main (int argc, char *argv[])
   int http_port = 0;
   char *ssl_cert = NULL;
   char *ssl_key = NULL;
-  char *display;
+  const char *display;
   int port = 0;
   const GOptionEntry entries[] = {
     { "port", 'p', 0, G_OPTION_ARG_INT, &http_port, "Httpd port", "PORT" },

gdk/wayland/wm-button-layout-translation.c

@@ -35,7 +35,7 @@ translate_buttons (char *layout, int *len_p)
 
   while ((button = strsep (&strp, ",")))
     {
-      char *gtkbutton;
+      const char *gtkbutton;
 
       if (strcmp (button, "menu") == 0)
         gtkbutton = "icon";

gdk/x11/gdkxftdefaults.c

@@ -81,9 +81,9 @@ parse_boolean (char *v)
 }
 
 static gboolean
-get_boolean_default (Display *dpy,
-		     gchar   *option,
-		     gboolean *value)
+get_boolean_default (Display     *dpy,
+		     const gchar *option,
+		     gboolean    *value)
 {
   gchar *v;
   gint i;
@@ -103,9 +103,9 @@ get_boolean_default (Display *dpy,
 }
 
 static gboolean
-get_double_default (Display *dpy,
-		    gchar   *option,
-		    gdouble *value)
+get_double_default (Display     *dpy,
+		    const gchar *option,
+		    gdouble     *value)
 {
   gchar    *v, *e;
   
@@ -126,9 +126,9 @@ get_double_default (Display *dpy,
 }
 
 static gboolean
-get_integer_default (Display *dpy,
-		     gchar   *option,
-		     gint    *value)
+get_integer_default (Display     *dpy,
+		     const gchar *option,
+		     gint        *value)
 {
   gchar *v, *e;
   

gdk/x11/xsettings-client.c

@@ -458,7 +458,7 @@ read_settings (GdkX11Screen *x11_screen,
 	  g_value_init (copy, G_VALUE_TYPE (setting));
 	  g_value_copy (setting, copy);
 	  g_hash_table_insert (x11_screen->xsettings, 
-			       "gtk-xft-dpi", copy);
+			       (gpointer) "gtk-xft-dpi", copy);
 	}
     }
 

gsk/gskvulkanrenderpass.c

@@ -662,13 +662,13 @@ gsk_vulkan_render_pass_add (GskVulkanRenderPass     *self,
 }
 
 static GskVulkanImage *
-gsk_vulkan_render_pass_get_node_as_texture (GskVulkanRenderPass *self,
-                                            GskVulkanRender     *render,
-                                            GskVulkanUploader   *uploader,
-                                            GskRenderNode       *node,
-                                            graphene_rect_t     *bounds,
-                                            GskVulkanClip       *current_clip,
-                                            graphene_rect_t     *tex_rect)
+gsk_vulkan_render_pass_get_node_as_texture (GskVulkanRenderPass   *self,
+                                            GskVulkanRender       *render,
+                                            GskVulkanUploader     *uploader,
+                                            GskRenderNode         *node,
+                                            const graphene_rect_t *bounds,
+                                            GskVulkanClip         *current_clip,
+                                            graphene_rect_t       *tex_rect)
 {
   GskVulkanImage *result;
   cairo_surface_t *surface;
@@ -889,7 +889,7 @@ gsk_vulkan_render_pass_upload (GskVulkanRenderPass  *self,
 {
   GskVulkanOp *op;
   guint i;
-  const GskVulkanClip *clip = NULL;
+  GskVulkanClip *clip = NULL;
 
   for (i = 0; i < self->render_ops->len; i++)
     {

gtk/a11y/gtkaccessibilityutil.c

@@ -136,7 +136,7 @@ atk_key_event_from_gdk_event_key (GdkEventKey       *key,
   if (string && string[0] &&
       (state & GDK_CONTROL_MASK ||
        g_unichar_isgraph (g_utf8_get_char (string))))
-    event->string = string;
+    event->string = (char *) string;
   else
     event->string = gdk_keyval_name (keyval);
 

gtk/gtkiconview.c

@@ -2270,7 +2270,7 @@ gtk_icon_view_button_press (GtkGestureMultiPress *gesture,
 }
 
 static gboolean
-button_event_modifies_selection (GdkEventButton *event)
+button_event_modifies_selection (const GdkEventButton *event)
 {
   guint state;
 

gtk/inspector/recorder.c

@@ -208,7 +208,7 @@ get_color_surface (const GdkRGBA *color)
 }
 
 static cairo_surface_t *
-get_linear_gradient_surface (gsize n_stops, GskColorStop *stops)
+get_linear_gradient_surface (gsize n_stops, const GskColorStop *stops)
 {
   cairo_surface_t *surface;
   cairo_t *cr;

meson.build

@@ -249,8 +249,6 @@ elif cc.get_id() == 'gcc' or cc.get_id() == 'clang'
     '-Wlogical-op',
     '-Wno-uninitialized',
     '-Wno-shadow',
-    '-Wno-int-conversion',
-    '-Wno-discarded-qualifiers',
     '-Werror=redundant-decls',
     '-Werror=implicit',
     '-Werror=nonnull',