I use vala 0.20.1.

I've created function with following syntax:

public void do_something(MyEnum type, string subtype, string identifier, HashTable<string,string> parameters) throws MyError

It is exported over DBus.

C compiler breaks the compilation with error "error: ‘parameters’ redeclared as different kind of symbol"

Underlying C code has function

static void _dbus_mynamespace_do_something (MyClass* self, GVariant* parameters, GDBusMethodInvocation* invocation) {
(...)
  GHashTable* parameters = NULL;
(...)
}

So indeed, parameters becomes redeclared.

If "parameters" is a reserved keyword for any reason IMO valac should catch it and return nice message, or maybe in such internal funcs variable names should be something less obvious?