Fix polygon / collection containment involving boundary points and nested empties

tests/relations/gcol.jsonc

@@ -243,4 +243,46 @@
       "touches":    ["F", "F"]
     }
   },
+  // An empty child does not prevent containment of the interior point.
+  {
+    "geoms": [
+      "GEOMETRYCOLLECTION (POINT EMPTY, POINT (1 1))",
+      "POLYGON ((0 0, 2 0, 2 2, 0 2, 0 0))"
+    ],
+    "dims": [ 0, 2 ],
+    "relate": [ "0FFFFF212", "0F2FF1FF2" ],
+    "predicates": {
+      "equals":     ["F", "F"],
+      "intersects": ["T", "T"],
+      "disjoint":   ["F", "F"],
+      "contains":   ["F", "T"],
+      "within":     ["T", "F"],
+      "covers":     ["F", "T"],
+      "coveredby":  ["T", "F"],
+      "crosses":    ["F", "F"],
+      "overlaps":   ["F", "F"],
+      "touches":    ["F", "F"]
+    }
+  },
+  // A collection containing only empty points is not within or coveredby the polygon.
+  {
+    "geoms": [
+      "GEOMETRYCOLLECTION (POINT EMPTY, POINT EMPTY)",
+      "POLYGON ((0 0, 2 0, 2 2, 0 2, 0 0))"
+    ],
+    "dims": [ 0, 2 ],
+    "relate": [ "FFFFFF212", "FF2FF1FF2" ],
+    "predicates": {
+      "equals":     ["F", "F"],
+      "intersects": ["F", "F"],
+      "disjoint":   ["T", "T"],
+      "contains":   ["F", "F"],
+      "within":     ["F", "F"],
+      "covers":     ["F", "F"],
+      "coveredby":  ["F", "F"],
+      "crosses":    ["F", "F"],
+      "overlaps":   ["F", "F"],
+      "touches":    ["F", "F"]
+    }
+  },
 ]

tests/relations/mpoint.jsonc

@@ -198,5 +198,68 @@
       "overlaps":   ["F", "F"],
       "touches":    ["F", "F"]
     }
+  },
+  // Within and contains with one interior point and one boundary point.
+  {
+    "geoms": [
+      "MULTIPOINT ((0 0), (1 1))",
+      "POLYGON ((0 0, 2 0, 2 2, 0 2, 0 0))"
+    ],
+    "dims": [ 0, 2 ],
+    "relate": [ "00FFFF212", "0F20F1FF2" ],
+    "predicates": {
+      "equals":     ["F", "F"],
+      "intersects": ["T", "T"],
+      "disjoint":   ["F", "F"],
+      "contains":   ["F", "T"],
+      "within":     ["T", "F"],
+      "covers":     ["F", "T"],
+      "coveredby":  ["T", "F"],
+      "crosses":    ["F", "F"],
+      "overlaps":   ["F", "F"],
+      "touches":    ["F", "F"]
+    }
+  },
+  // All points lie on the polygon boundary, so coveredby is true but within is false.
+  {
+    "geoms": [
+      "MULTIPOINT ((0 0), (1 0))",
+      "POLYGON ((0 0, 2 0, 2 2, 0 2, 0 0))"
+    ],
+    "dims": [ 0, 2 ],
+    "relate": [ "F0FFFF212", "FF20F1FF2" ],
+    "predicates": {
+      "equals":     ["F", "F"],
+      "intersects": ["T", "T"],
+      "disjoint":   ["F", "F"],
+      "contains":   ["F", "F"],
+      "within":     ["F", "F"],
+      "covers":     ["F", "T"],
+      "coveredby":  ["T", "F"],
+      "crosses":    ["F", "F"],
+      "overlaps":   ["F", "F"],
+      "touches":    ["T", "T"]
+    }
+  },
+  // An interior point followed by an outside point is neither within nor coveredby.
+  {
+    "geoms": [
+      "MULTIPOINT ((1 1), (3 3))",
+      "POLYGON ((0 0, 2 0, 2 2, 0 2, 0 0))"
+    ],
+    "dims": [ 0, 2 ],
+    "relate": [ "0F0FFF212", "0F2FF10F2" ],
+    "predicates": {
+      "equals":     ["F", "F"],
+      "intersects": ["T", "T"],
+      "disjoint":   ["F", "F"],
+      "contains":   ["F", "F"],
+      "within":     ["F", "F"],
+      "covers":     ["F", "F"],
+      "coveredby":  ["F", "F"],
+      "crosses":    ["T", "T"],
+      "overlaps":   ["F", "F"],
+      "touches":    ["F", "F"]
+    }
   }
-]
+]

tg.c

@@ -5939,12 +5939,18 @@ static bool poly_covers_base_geom(struct tg_poly *poly,
         case TG_MULTIPOLYGON:
         case TG_GEOMETRYCOLLECTION: 
             if (!geom->multi || geom->multi->ngeoms == 0) return false;
+            int empty_count = 0;
             for (int i = 0; i < geom->multi->ngeoms; i++) {
+                if ((geom->multi->geoms[i]->head.flags&IS_EMPTY) == IS_EMPTY) {
+                    ++empty_count;
+                    continue;
+                }
+
                 if (!poly_covers_geom(poly, geom->multi->geoms[i])) {
                     return false;
                 }
             }
-            return true;
+            return empty_count != geom->multi->ngeoms;
         }
     }
     return false;
@@ -6124,12 +6130,18 @@ static bool poly_contains_base_geom(struct tg_poly *poly,
         case TG_GEOMETRYCOLLECTION: {
             bool contains = false;
             if (geom->multi && geom->multi->ngeoms > 0) {
-                contains = true;
                 for (int i = 0; i < geom->multi->ngeoms; i++) {
-                    if (!poly_contains_geom(poly, geom->multi->geoms[i])) {
+                    if ((geom->multi->geoms[i]->head.flags&IS_EMPTY) == IS_EMPTY) {
+                        continue;
+                    }
+
+                    if (!poly_covers_geom(poly, geom->multi->geoms[i])) {
                         contains = false;
                         break;
                     }
+
+                    // Require at least one interior intersection
+                    contains = contains || poly_contains_geom(poly, geom->multi->geoms[i]);
                 }
             }
             return contains;