Use generic signature for local variables with entry in LVTT

This uses the generic type information of the local variable type table for the
type of local variables. Before, no local variable was considered to a have
generic type.

Author: Matthias Güdemann

jbmc/src/java_bytecode/java_local_variable_table.cpp

@@ -768,9 +768,20 @@ void java_bytecode_convert_methodt::setup_local_variables(
             << " name " << v.var.name << " v.var.descriptor '"
             << v.var.descriptor << "' holes " << v.holes.size() << eom;
 #endif
-    typet t;
-    // TODO: might need changing once descriptor/signature issue is resolved
-    t=java_type_from_string(v.var.descriptor);
+
+    const std::string &method_name = id2string(method_id);
+    const size_t method_name_end = method_name.rfind(":(");
+    const size_t class_name_end = method_name.rfind('.', method_name_end);
+    INVARIANT(
+      method_name_end != std::string::npos &&
+        class_name_end != std::string::npos,
+      "A method name has the format class `.` method `:(`signature`)`.");
+    const std::string class_name = method_name.substr(0, class_name_end);
+
+    const typet t = v.var.signature.has_value()
+                      ? java_type_from_string_with_exception(
+                          v.var.descriptor, v.var.signature, class_name)
+                      : java_type_from_string(v.var.descriptor);
 
     std::ostringstream id_oss;
     id_oss << method_id << "::" << v.var.start_pc << "::" << v.var.name;