support for ensuring that a vector can be treated as having a homogeneous type

src/Val.cc

@@ -3653,6 +3653,50 @@ VectorValPtr VectorVal::Order(Func* cmp_func)
 	return result_v;
 	}
 
+bool VectorVal::Concretize(const TypePtr& t)
+	{
+	if ( ! any_yield )
+		// Could do a same_type() call here, but really this case
+		// shouldn't happen in any case.
+		return yield_type->Tag() == t->Tag();
+
+	if ( ! vector_val )
+		// Trivially concretized.
+		return true;
+
+	auto n = vector_val->size();
+	for ( auto i = 0U; i < n; ++i )
+		{
+		auto& v = (*vector_val)[i];
+		if ( ! v )
+			// Vector hole does not require concretization.
+			continue;
+
+		auto& vt_i = yield_types ? (*yield_types)[i] : yield_type;
+		if ( vt_i->Tag() == TYPE_ANY )
+			{ // Do the concretization.
+			ValPtr any_v = {NewRef{}, v->AsAny()};
+			auto& vt = any_v->GetType();
+			if ( vt->Tag() != t->Tag() )
+				return false;
+
+			v = ZVal(any_v, t);
+			}
+
+		else if ( vt_i->Tag() != t->Tag() )
+			return false;
+		}
+
+	// Require that this vector be treated consistently in the future.
+	yield_type = t;
+	managed_yield = ZVal::IsManagedType(yield_type);
+	delete yield_types;
+	yield_types = nullptr;
+	any_yield = false;
+
+	return true;
+	}
+
 unsigned int VectorVal::Resize(unsigned int new_num_elements)
 	{
 	unsigned int oldsize = vector_val->size();

src/Val.h

@@ -1553,6 +1553,22 @@ public:
 	 */
 	VectorValPtr Order(Func* cmp_func = nullptr);
 
+	/**
+	 * Ensures that the vector can be used as a "vector of t".  In
+	 * general, this is only relevant for objects that are typed as
+	 * "vector of any", making sure that each element is in fact
+	 * of type "t", and is internally represented as such so that
+	 * this object can be used directly without any special-casing.
+	 *
+	 * Returns true if the object is compatible with "vector of t"
+	 * (including if it's not a vector-of-any but instead already a
+	 * vector-of-t), false if not compatible.
+	 * @param t  The yield type to concretize to.
+	 * @return  True if the object is compatible with vector-of-t, false
+	 * if not.
+	 */
+	bool Concretize(const TypePtr& t);
+
 	ValPtr ValAt(unsigned int index) const	{ return At(index); }
 
 	bool Has(unsigned int index) const