Fix issue in tree_remove when it is root node (part 1)

m-tree.h

@@ -759,6 +759,8 @@ typedef int32_t m_tr33_index_t;
             if (parent >= 0 && it.tree->tab[parent].child == it.index) {      \
                 M_ASSERT(left == M_TR33_NO_NODE);                             \
                 it.tree->tab[parent].child = right;                           \
+            } else if (parent == M_TR33_ROOT_NODE) {                          \
+                it.tree->root_index = right;                                  \
             }                                                                 \
         } else {                                                              \
             /* Merge the child with the current siblings */                   \
@@ -782,6 +784,8 @@ typedef int32_t m_tr33_index_t;
             if (parent >= 0 && it.tree->tab[parent].child == it.index) {      \
                 M_ASSERT(left == M_TR33_NO_NODE);                             \
                 it.tree->tab[parent].child = child;                           \
+            } else if (parent == M_TR33_ROOT_NODE) {                          \
+                it.tree->root_index = child;                                  \
             }                                                                 \
         }                                                                     \
         /* Free the node to the allocator */                                  \

tests/test-mtree.c

@@ -424,17 +424,42 @@ static void test_gen(void)
   tree_init_move(t0, t);
   tree_init_set(t, t0);
   assert(tree_equal_p(t, t0));
+
+  tree_set(t, t0);
+  tree_it_t it;
+  for(size_t i = 1; i < tree_size(t0); i++) {
+    it = tree_it(t);
+    tree_next(&it);
+    bool b = tree_remove(it);
+    assert(b);
+    assert(tree_size(t)== tree_size(t0) - i);
+  }
+  bool b = tree_remove(tree_it(t));
+  assert(b);
+  assert(tree_size(t)== 0);
+
+  tree_set(t, t0);
+  for(size_t i = 1; i < tree_size(t0); i++) {
+    it = tree_it(t);
+    b = tree_remove(it);
+    assert(b);
+    assert(tree_size(t)== tree_size(t0) - i);
+  }
+  b = tree_remove(tree_it(t));
+  assert(b);
+  assert(tree_size(t)== 0);
+
   for(size_t i = 0; i < tree_size(t0); i++) {
     tree_set(t, t0);
     size_t j = 0;
-    for(tree_it_t it = tree_it(t); j <= i && !tree_end_p(it); tree_next(&it), j++) {
+    for(it = tree_it(t); j <= i && !tree_end_p(it); tree_next(&it), j++) {
       if (i ==j)
         *tree_ref(it) = 147852369;
     }
     assert(!tree_equal_p(t, t0));
     tree_set(t, t0);
     j = 0;
-    for(tree_it_t it = tree_it(t); j <= i && !tree_end_p(it); tree_next(&it), j++) {
+    for(it = tree_it(t); j <= i && !tree_end_p(it); tree_next(&it), j++) {
       if (i ==j)
         tree_remove(it);
     }
@@ -442,6 +467,7 @@ static void test_gen(void)
     assert(!tree_equal_p(t, t0));
     assert(!tree_equal_p(t0, t));
   }
+
   tree_move(t, t0);
   tree_clear(t);
 }