Created attachment 231059 [details]
Testcase which gives rise to the problem.

Dear hard-working vala developers :)

When deriving a class from HashTable and accessing its base constructor (i.e. the constructor of HashTable) using 

base(str_hash, str_equal);

valac generates this bad c code (where "Derived" is the name of the class derived from HashTable):

self = (Derived*) g_hash_table_new_full (_tmp0_, _tmp1_);

But g_hash_table_new_full requires two more parameters.

Constructing a HashTable using

HashTable table = new HashTable<string, string> (str_hash, str_equal);

works. So does accessing the base constructor by writing

base.full(str_hash, str_equal, null, null);

I attached a testcase for this.