Fixed the FunctionToStaticMethod pass to make sure we do not apply it when the function and class have different translation units. This can be improved in the future, for which I left a TODO.

src/Generator/Passes/FunctionToStaticMethodPass.cs

@@ -26,12 +26,18 @@ namespace CppSharp.Passes
             if (@class == null)
                 return false;
 
+            // TODO: If the translation units of the declarations are different,
+            // and we apply the pass, we might need additional includes in the
+            // generated translation unit of the class.
+            if (@class.TranslationUnit != function.TranslationUnit)
+                return false;
+
             // Clean up the name of the function now that it will be a static method.
             var name = function.Name.Substring(@class.Name.Length);
             function.ExplicityIgnored = true;
 
             // Create a new fake method so it acts as a static method.
-            var method = new Method()
+            var method = new Method
             {
                 Namespace = @class,
                 OriginalNamespace = function.Namespace,