Don't let GMSH physicals overwrite each other

src/mesh/gmsh_io.C

@@ -175,14 +175,13 @@ void GmshIO::read_mesh(std::istream & in)
   // actually blocks of lower-dimensional elements.
   std::set<subdomain_id_type> lower_dimensional_blocks;
 
-  // Mapping from physical id -> (physical dim, physical name) pairs.
+  // Mapping from (physical id, physical dim) -> physical name.
   // These can refer to either "sidesets" or "subdomains"; we need to
   // wait until the Mesh has been read to know which is which.  Note
-  // that we are using 'int' as the key here rather than
+  // that we are using ptrdiff_t as the key here rather than
   // subdomain_id_type or boundary_id_type, since at this point, it
   // could be either.
-  typedef std::pair<unsigned, std::string> GmshPhysical;
-  std::map<int, GmshPhysical> gmsh_physicals;
+  std::map<std::pair<std::ptrdiff_t, unsigned>, std::string> gmsh_physicals;
 
   // map to hold the node numbers for translation
   // note the the nodes can be non-consecutive
@@ -267,7 +266,7 @@ void GmshIO::read_mesh(std::istream & in)
                   phys_name.erase(std::remove(phys_name.begin(), phys_name.end(), '"'), phys_name.end());
 
                   // Record this ID for later assignment of subdomain/sideset names.
-                  gmsh_physicals[phys_id] = std::make_pair(phys_dim, phys_name);
+                  gmsh_physicals[std::make_pair(phys_id, phys_dim)] = phys_name;
 
                   // If 's' also contains the libmesh-specific string
                   // "lower_dimensional_block", add this block ID to
@@ -790,9 +789,8 @@ void GmshIO::read_mesh(std::istream & in)
             for (const auto & pr : gmsh_physicals)
             {
               // Extract data
-              int phys_id = pr.first;
-              unsigned phys_dim = pr.second.first;
-              const std::string & phys_name = pr.second.second;
+              auto [phys_id, phys_dim] = pr.first;
+              const std::string & phys_name = pr.second;
 
               // If the physical's dimension matches the largest
               // dimension we've seen, it's a subdomain name.

tests/mesh/mesh_input.C

@@ -203,6 +203,8 @@ public:
   CPPUNIT_TEST( testGoodSTL );
   CPPUNIT_TEST( testGoodSTLBinary );
 
+  CPPUNIT_TEST( testGmshBCIDOverlap );
+
 #ifdef LIBMESH_HAVE_TETGEN
   CPPUNIT_TEST( testTetgenIO );
 #endif
@@ -1562,6 +1564,32 @@ public:
     CPPUNIT_ASSERT_EQUAL(mesh.n_elem(), dof_id_type(14));
   }
 
+  void testGmshBCIDOverlap ()
+  {
+    LOG_UNIT_TEST;
+
+    Mesh mesh(*TestCommWorld);
+
+    GmshIO gmsh_io(mesh);
+
+    if (mesh.processor_id() == 0)
+      gmsh_io.read("meshes/bcid_overlap.msh");
+    MeshCommunication().broadcast(mesh);
+
+    CPPUNIT_ASSERT_EQUAL(mesh.get_boundary_info().get_sideset_name_map().size(),
+                         std::size_t(2));
+    CPPUNIT_ASSERT_EQUAL(mesh.get_boundary_info().sideset_name(1),
+                         std::string("srfBC4A"));
+    CPPUNIT_ASSERT_EQUAL(mesh.get_boundary_info().sideset_name(2),
+                         std::string("srfBC4B"));
+    CPPUNIT_ASSERT_EQUAL(mesh.get_subdomain_name_map().size(),
+                         std::size_t(2));
+    CPPUNIT_ASSERT_EQUAL(mesh.subdomain_name(1),
+                         std::string("volBC3A"));
+    CPPUNIT_ASSERT_EQUAL(mesh.subdomain_name(2),
+                         std::string("volBC3B"));
+  }
+
   void testGoodSTL ()
   {
     LOG_UNIT_TEST;

tests/meshes/bcid_overlap.msh

@@ -0,0 +1,184 @@
+$MeshFormat
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