Fix gcc-6 bug in the rand test.
diff --git a/test/rand.cpp b/test/rand.cpp
index bb90ad9..b5cf801 100644
--- a/test/rand.cpp
+++ b/test/rand.cpp
@@ -10,8 +10,11 @@
#include <cstdlib>
#include "main.h"
+// For GCC-6, if this function is inlined then there seems to be an optimization
+// bug that triggers a failure. This failure goes away if you access `r` in
+// in any way, and for any other compiler.
template <typename Scalar>
-Scalar check_in_range(Scalar x, Scalar y) {
+EIGEN_DONT_INLINE Scalar check_in_range(Scalar x, Scalar y) {
Scalar r = internal::random<Scalar>(x, y);
VERIFY(r >= x);
if (y >= x) {
