RequirementMachine: Superclass and concrete type symbols should not contain type variables

Author: slavapestov

lib/AST/RequirementMachine/Symbol.cpp

@@ -87,6 +87,7 @@ struct Symbol::Storage final
   Storage(Symbol::Kind kind, CanType type, ArrayRef<Term> substitutions) {
     assert(kind == Symbol::Kind::Superclass ||
            kind == Symbol::Kind::ConcreteType);
+    assert(!type->hasTypeVariable());
     assert(type->hasTypeParameter() != substitutions.empty());
 
     Kind = unsigned(kind);