use unsigned int for all layers.

source/blender/blenkernel/depsgraph_private.h

@@ -64,8 +64,8 @@ typedef struct DagNode
 	void * ob;
 	void * first_ancestor;
 	int ancestor_count;
-	int lay;			// accumulated layers of its relations + itself
-	int scelay;			// layers due to being in scene
+	unsigned int lay;			// accumulated layers of its relations + itself
+	unsigned int scelay;			// layers due to being in scene
 	int lasttime;		// if lasttime != DagForest->time, this node was not evaluated yet for flushing
 	int BFS_dist;		// BFS distance
 	int DFS_dist;		// DFS distance

source/blender/blenkernel/intern/anim.c

@@ -843,7 +843,8 @@ static void vertex_duplilist(ListBase *lb, ID *id, Scene *scene, Object *par, fl
 	GroupObject * go = NULL;
 	EditMesh *em;
 	float vec[3], no[3], pmat[4][4];
-	int lay, totvert, a, oblay;
+	int totvert, a, oblay;
+	unsigned int lay;
 	
 	copy_m4_m4(pmat, par->obmat);
 	
@@ -1153,8 +1154,9 @@ static void new_particle_duplilist(ListBase *lb, ID *UNUSED(id), Scene *scene, O
 	float ctime, pa_time, scale = 1.0f;
 	float tmat[4][4], mat[4][4], pamat[4][4], vec[3], size=0.0;
 	float (*obmat)[4], (*oldobmat)[4];
-	int lay, a, b, counter, hair = 0;
+	int a, b, counter, hair = 0;
 	int totpart, totchild, totgroup=0, pa_num;
+	unsigned int lay;
 
 	if(psys==0) return;
 	

source/blender/blenkernel/intern/object.c

@@ -1476,7 +1476,7 @@ static void armature_set_id_extern(Object *ob)
 {
 	bArmature *arm= ob->data;
 	bPoseChannel *pchan;
-	int lay= arm->layer_protected;
+	unsigned int lay= arm->layer_protected;
 	
 	for (pchan = ob->pose->chanbase.first; pchan; pchan=pchan->next) {
 		if(!(pchan->bone->layer & lay))

source/blender/editors/render/render_internal.c

@@ -401,7 +401,7 @@ static int screen_render_exec(bContext *C, wmOperator *op)
 	Image *ima;
 	View3D *v3d= CTX_wm_view3d(C);
 	Main *mainp= CTX_data_main(C);
-	int lay= (v3d)? v3d->lay: scene->lay;
+	unsigned int lay= (v3d)? v3d->lay: scene->lay;
 
 	if(re==NULL) {
 		re= RE_NewRender(scene->id.name);

source/blender/editors/space_view3d/space_view3d.c

@@ -915,7 +915,7 @@ static int view3d_context(const bContext *C, const char *member, bContextDataRes
 	View3D *v3d= CTX_wm_view3d(C);
 	Scene *scene= CTX_data_scene(C);
 	Base *base;
-	int lay = v3d ? v3d->lay:scene->lay; /* fallback to the scene layer, allows duplicate and other oject operators to run outside the 3d view */
+	unsigned int lay = v3d ? v3d->lay:scene->lay; /* fallback to the scene layer, allows duplicate and other oject operators to run outside the 3d view */
 
 	if(CTX_data_dir(member)) {
 		static const char *dir[] = {

source/blender/editors/space_view3d/view3d_header.c

@@ -511,7 +511,7 @@ void uiTemplateHeader3D(uiLayout *layout, struct bContext *C)
 	}
  		
 	if(obedit==NULL && v3d->localvd==NULL) {
-		int ob_lay = ob ? ob->lay : 0;
+		unsigned int ob_lay = ob ? ob->lay : 0;
 		
 		/* Layers */
 		if (v3d->scenelock)

source/blender/makesdna/DNA_armature_types.h

@@ -91,7 +91,7 @@ typedef struct bArmature {
 	
 	int			pad;
 	
-	int			layer, layer_protected;		/* for buttons to work, both variables in this order together */
+	unsigned int layer, layer_protected;		/* for buttons to work, both variables in this order together */
 	
 // XXX depreceated... old animaton system (armature only viz) ---
 	short		ghostep, ghostsize;		/* number of frames to ghosts to show, and step between them  */

source/blender/makesdna/DNA_view3d_types.h

@@ -153,7 +153,8 @@ typedef struct View3D {
 	
 	char ob_centre_bone[32];		/* optional string for armature bone to define center */
 	
-	int lay, layact;
+	unsigned int lay;
+	int layact;
 	
 	/**
 	 * The drawing mode for the 3d display. Set to OB_WIRE, OB_SOLID,