GCC 9.3.0 compilation error

[AlexBolotsin]

Hi,

Nice example of intrinsic geometry you have here.
MarchingCubes.cpp method merge_vertex uses iterators to find a vertex set.
On fresh ubuntu 20.04 it generates an error:

marchingcubes.cpp:464:10: error: no match for ‘operator!=’ (operand types are ‘std::unordered_set<Vertex*>::const_iterator’ {aka ‘std::__detail::_Node_const_iterator<Vertex*, true, false>’} and ‘std::unordered_set<Vertex*, vertex_hash, vertex_equals>::const_iterator’ {aka ‘std::__detail::_Node_const_iterator<Vertex*, true, true>’})
  464 |     if(u != vertex_set.cend()) {
      |        ~ ^~ ~~~~~~~~~~~~~~~~~
      |        |                   |
      |        |                   _Node_const_iterator<[...],[...],true>
      |        _Node_const_iterator<[...],[...],false>

3rd value of template is different which make em different types.

There is a quickfix for it

diff --git a/marchingcubes.cpp b/marchingcubes.cpp
index 3a6ffed..8254cb5 100644
--- a/marchingcubes.cpp
+++ b/marchingcubes.cpp
@@ -459,9 +459,9 @@ bool is_degenerate(Vertex* v0, Vertex* v1, Vertex* v2)
 
 Vertex* merge_vertex(Vertex* v, unordered_set<Vertex*, vertex_hash, vertex_equals>& vertex_set, Mesh& mesh)
 {
-    unordered_set<Vertex*>::const_iterator u = vertex_set.find(v);
+    unordered_set<Vertex*, vertex_hash, vertex_equals>::const_iterator u = vertex_set.find(v);
 
-    if(u != vertex_set.end()) {
+    if(u != vertex_set.cend()) {
         delete v;
         return *u;
     }