init NhRect, before passing to selection_getbounds

selection_getbounds() has a check and early return.
Initialization will ensure a known state if that early return
were ever taken.

This is an alternative approach to pr #1163.

include/decl.h

@@ -1150,6 +1150,7 @@ struct const_globals {
     const struct obj zeroobj;      /* used to zero out a struct obj */
     const struct monst zeromonst;  /* used to zero out a struct monst */
     const anything zeroany;        /* used to zero out union any */
+    const NhRect zeroNhRect;       /* used to zero out NhRect */
 };
 
 extern const struct const_globals cg;

src/decl.c

@@ -957,6 +957,7 @@ const struct const_globals cg = {
     DUMMY, /* zeroobj */
     DUMMY, /* zeromonst */
     DUMMY, /* zeroany */
+    DUMMY, /* zeroNhRect */
 };
 
 #define ZERO(x) memset(&x, 0, sizeof(x))

src/nhlsel.c

@@ -203,7 +203,7 @@ l_selection_numpoints(lua_State *L)
     struct selectionvar *sel = l_selection_check(L, 1);
     coordxy x, y;
     int ret = 0;
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     selection_getbounds(sel, &rect);
 
@@ -281,7 +281,7 @@ l_selection_and(lua_State *L)
     struct selectionvar *sela = l_selection_check(L, 1);
     struct selectionvar *selb = l_selection_check(L, 2);
     struct selectionvar *selr = l_selection_push_new(L);
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     rect_bounds(sela->bounds, selb->bounds, &rect);
 
@@ -304,7 +304,7 @@ l_selection_or(lua_State *L)
     struct selectionvar *sela = l_selection_check(L, 1);
     struct selectionvar *selb = l_selection_check(L, 2);
     struct selectionvar *selr = l_selection_push_new(L);
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     rect_bounds(sela->bounds, selb->bounds, &rect);
 
@@ -328,7 +328,7 @@ l_selection_xor(lua_State *L)
     struct selectionvar *sela = l_selection_check(L, 1);
     struct selectionvar *selb = l_selection_check(L, 2);
     struct selectionvar *selr = l_selection_push_new(L);
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     rect_bounds(sela->bounds, selb->bounds, &rect);
 
@@ -355,7 +355,7 @@ l_selection_sub(lua_State *L)
     struct selectionvar *sela = l_selection_check(L, 1);
     struct selectionvar *selb = l_selection_check(L, 2);
     struct selectionvar *selr = l_selection_push_new(L);
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     rect_bounds(sela->bounds, selb->bounds, &rect);
 
@@ -445,7 +445,7 @@ static int
 l_selection_getbounds(lua_State *L)
 {
     struct selectionvar *sel = l_selection_check(L, 1);
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     selection_getbounds(sel, &rect);
     lua_settop(L, 0);
@@ -904,7 +904,7 @@ l_selection_iterate(lua_State *L)
     int argc = lua_gettop(L);
     struct selectionvar *sel = (struct selectionvar *) 0;
     int x, y;
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     if (argc == 2 && lua_type(L, 2) == LUA_TFUNCTION) {
         sel = l_selection_check(L, 1);

src/sp_lev.c

@@ -4675,7 +4675,7 @@ struct selectionvar *
 selection_not(struct selectionvar *s)
 {
     int x, y;
-    NhRect tmprect;
+    NhRect tmprect = cg.zeroNhRect;
 
     for (x = 0; x < s->wid; x++)
         for (y = 0; y < s->hei; y++)
@@ -4689,7 +4689,7 @@ selection_filter_mapchar(struct selectionvar *ov,  xint16 typ, int lit)
 {
     int x, y;
     struct selectionvar *ret;
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     if (!ov)
         return NULL;
@@ -4727,7 +4727,7 @@ selection_filter_percent(
 {
     int x, y;
     struct selectionvar *ret;
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     if (!ov)
         return NULL;
@@ -4753,7 +4753,7 @@ selection_rndcoord(
     int idx = 0;
     int c;
     int dx, dy;
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     selection_getbounds(ov, &rect);
 
@@ -4794,7 +4794,7 @@ selection_do_grow(struct selectionvar *ov, int dir)
 {
     coordxy x, y;
     struct selectionvar *tmp;
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     if (!ov)
         return;
@@ -5222,7 +5222,7 @@ selection_iterate(
     genericptr_t arg)
 {
     coordxy x, y;
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     if (!ov)
         return;
@@ -5645,7 +5645,7 @@ lspo_replace_terrain(lua_State *L)
     lua_Integer x1, y1, x2, y2;
     int chance;
     int tolit;
-    NhRect rect;
+    NhRect rect = cg.zeroNhRect;
 
     create_des_coder();