Remove using std::string from port.h
Change-Id: I7376f5e7eace22ec1fc05a61eaa858594f08682d
diff --git a/internal/ceres/array_utils.cc b/internal/ceres/array_utils.cc
index a22eb61..3eb5ea4 100644
--- a/internal/ceres/array_utils.cc
+++ b/internal/ceres/array_utils.cc
@@ -41,6 +41,8 @@
namespace ceres {
namespace internal {
+using std::string;
+
// It is a near impossibility that user code generates this exact
// value in normal operation, thus we will use it to fill arrays
// before passing them to user code. If on return an element of the
