Ensure Java stubbing names parameters

For functions with a body we require that parameters are named so that
we can generate assignments to them (even when the body may not read the
value). Also guard against future regressions by sanity checking
parameter names for any converted function.

Author: tautschnig

jbmc/src/java_bytecode/simple_method_stubbing.cpp

@@ -148,12 +148,29 @@ void java_simple_method_stubst::create_method_stub_at(
 void java_simple_method_stubst::create_method_stub(symbolt &symbol)
 {
   code_blockt new_instructions;
-  const java_method_typet &required_type = to_java_method_type(symbol.type);
+  java_method_typet &required_type = to_java_method_type(symbol.type);
 
   // synthetic source location that contains the opaque function name only
   source_locationt synthesized_source_location;
   synthesized_source_location.set_function(symbol.name);
 
+  // make sure all parameters are named
+  for(auto &parameter : required_type.parameters())
+  {
+    if(parameter.get_identifier().empty())
+    {
+      symbolt &parameter_symbol = fresh_java_symbol(
+        parameter.type(),
+        "#anon",
+        synthesized_source_location,
+        symbol.name,
+        symbol_table);
+      parameter_symbol.is_parameter = true;
+      parameter.set_base_name(parameter_symbol.base_name);
+      parameter.set_identifier(parameter_symbol.name);
+    }
+  }
+
   // Initialize the return value or `this` parameter under construction.
   // Note symbol.type is required_type, but with write access
   // Probably required_type should not be const

src/goto-programs/goto_convert_functions.cpp

@@ -159,6 +159,15 @@ void goto_convert_functionst::convert_function(
      symbol.is_compiled()) /* goto_inline may have removed the body */
     return;
 
+  // we have a body, make sure all parameter names are valid
+  for(const auto &p : f.parameter_identifiers)
+  {
+    DATA_INVARIANT(!p.empty(), "parameter identifier should not be empty");
+    DATA_INVARIANT(
+      symbol_table.has_symbol(p),
+      "parameter identifier must be a known symbol");
+  }
+
   lifetimet parent_lifetime = lifetime;
   lifetime = identifier == INITIALIZE_FUNCTION ? lifetimet::STATIC_GLOBAL
                                                : lifetimet::AUTOMATIC_LOCAL;