A system has a generic class FOO with an inline C external function
that just returns its argument.  When another class creates an
instance of FOO [DOUBLE] and calls the external function on it, the
result is correct.  Then the type in the creation expression is
changed to FOO [ARRAY [DOUBLE]] and changes are melted.  Finally the
creation expression type is changed back to FOO [DOUBLE] and changes
are melted again.  System execution then produces the wrong output.

Discovered in release 5.4.0610.