From 7099bb60969585608d1f199b65f51e86307045de Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Fri, 13 Nov 2020 11:32:18 +1100
Subject: [PATCH] AP_NavEKF2: fixed gcc 9.3 build error

gcc 9.3 doesn't like the use of get_accel(i) when array length is 1
---
 libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp b/libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp
index 2056c345c5..2f309519e7 100644
--- a/libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp
+++ b/libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp
@@ -971,6 +971,11 @@ float NavEKF2_core::MagDeclination(void) const
  */
 void NavEKF2_core::learnInactiveBiases(void)
 {
+#if INS_MAX_INSTANCES == 1
+    inactiveBias[0].gyro_bias = stateStruct.gyro_bias;
+    inactiveBias[0].gyro_scale = stateStruct.gyro_scale;
+    inactiveBias[0].accel_zbias = stateStruct.accel_zbias;
+#else
     const auto &ins = dal.ins();
 
     // learn gyro biases
@@ -1029,6 +1034,7 @@ void NavEKF2_core::learnInactiveBiases(void)
             inactiveBias[i].accel_zbias -= error * (1.0e-4f * dtEkfAvg);
         }
     }
+#endif
 }
 
 // Writes the default equivalent airspeed in m/s to be used in forward flight if a measured airspeed is required and not available.