Arch: import IFC, Materials, make merge materials working on duplicat…

…e label setting

src/Mod/Arch/importIFC.py

@@ -1261,7 +1261,7 @@ def insert(srcfile, docname, skip=[], only=[], root=None, preferences=None):
         # print(material.id())
 
         mdict = {}
-        # on ifc import only the "DiffuseColor" of the material dictionary is initialized
+        # on ifc import only the "Description" and "DiffuseColor" (if it was read) of the material dictionary will be initialized
         # on editing material in Arch Gui a lot more keys of the material dictionary are initialized even with empty values
         # TODO: there should be a generic material obj init method which will be used by Arch Gui, import IFC, FEM, etc
 
@@ -1271,7 +1271,10 @@ def insert(srcfile, docname, skip=[], only=[], root=None, preferences=None):
             name = material.Name
             if six.PY2:
                 name = name.encode("utf8")
-        mdict["Name"] = name
+        # mdict["Name"] = name on duplicate material names in IFC this could result in crash
+        # https://forum.freecadweb.org/viewtopic.php?f=23&t=63260
+        # thus use "Description"
+        mdict["Description"] = name
 
         # get material color
         # the "DiffuseColor" of a material should never be "None"
@@ -1295,16 +1298,16 @@ def insert(srcfile, docname, skip=[], only=[], root=None, preferences=None):
         if preferences["MERGE_MATERIALS"]:
             for added_mat in added_mats:
                 if (
-                    # added_mat.Material["Name"] == name
-                    # above does not work because FreeCAD would crash in some circumstances
-                    # https://forum.freecadweb.org/viewtopic.php?f=23&t=63260
-                    added_mat.Label == name
-                    and ("DiffuseColor" in mdict and "DiffuseColor" in added_mat.Material)
-                    and mdict["DiffuseColor"] == added_mat.Material["DiffuseColor"]
+                    "Description" in added_mat.Material
+                    and "DiffuseColor" in added_mat.Material 
+                    and "DiffuseColor" in mdict  # Description has been set thus it is in mdict
+                    and added_mat.Material["Description"] == mdict["Description"]
+                    and added_mat.Material["DiffuseColor"] == mdict["DiffuseColor"]
                 ):
                     matobj = added_mat
                     add_material = False
                     break
+
         # add a new material object
         if add_material is True:
             matobj = Arch.makeMaterial(name=name)