renamed Combine to TryCombine to show the intent more clear.

TryCombine should never throw exception.

src/VisualStudio/Core/Def/Implementation/TableDataSource/AbstractTableEntriesSnapshot.cs

@@ -182,7 +182,18 @@ protected bool TryNavigateTo(Workspace workspace, DocumentId documentId, int lin
 
         protected string GetFileName(string original, string mapped)
         {
-            return mapped == null ? original : original == null ? mapped : FilePathUtilities.Combine(original, mapped);
+            return mapped == null ? original : original == null ? mapped : Combine(original, mapped);
+        }
+
+        private string Combine(string path1, string path2)
+        {
+            string result;
+            if (FilePathUtilities.TryCombine(path1, path2, out result))
+            {
+                return result;
+            }
+
+            return string.Empty;
         }
 
         protected string GetProjectName(Workspace workspace, ProjectId projectId)

src/Workspaces/Core/Desktop/InternalUtilities/FilePathUtilities.cs

@@ -104,16 +104,18 @@ public static bool PathsEqual(string path1, string path2)
             return string.Compare(path1, path2, StringComparison.OrdinalIgnoreCase) == 0;
         }
 
-        public static string Combine(string path1, string path2)
+        public static bool TryCombine(string path1, string path2, out string result)
         {
             try
             {
                 // don't throw exception when either path1 or path2 contains illegal path char
-                return Path.Combine(path1, path2);
+                result = Path.Combine(path1, path2);
+                return true;
             }
             catch
             {
-                return string.Empty;
+                result = null;
+                return false;
             }
         }
     }