AP_AHRS: get_variances does not return offset

the offset is not a variance and is not actually used by any callers of this function

libraries/AP_AHRS/AP_AHRS.h

@@ -528,7 +528,7 @@ public:
     // indicates perfect consistency between the measurement and the EKF solution and a value of of 1 is the maximum
     // inconsistency that will be accepted by the filter
     // boolean false is returned if variances are not available
-    virtual bool get_variances(float &velVar, float &posVar, float &hgtVar, Vector3f &magVar, float &tasVar, Vector2f &offset) const {
+    virtual bool get_variances(float &velVar, float &posVar, float &hgtVar, Vector3f &magVar, float &tasVar) const {
         return false;
     }
 

libraries/AP_AHRS/AP_AHRS_NavEKF.cpp

@@ -2051,7 +2051,7 @@ bool AP_AHRS_NavEKF::get_innovations(Vector3f &velInnov, Vector3f &posInnov, Vec
 // indicates prefect consistency between the measurement and the EKF solution and a value of of 1 is the maximum
 // inconsistency that will be accpeted by the filter
 // boolean false is returned if variances are not available
-bool AP_AHRS_NavEKF::get_variances(float &velVar, float &posVar, float &hgtVar, Vector3f &magVar, float &tasVar, Vector2f &offset) const
+bool AP_AHRS_NavEKF::get_variances(float &velVar, float &posVar, float &hgtVar, Vector3f &magVar, float &tasVar) const
 {
     switch (ekf_type()) {
     case EKFType::NONE:
@@ -2059,17 +2059,21 @@ bool AP_AHRS_NavEKF::get_variances(float &velVar, float &posVar, float &hgtVar,
         return false;
 
 #if HAL_NAVEKF2_AVAILABLE
-    case EKFType::TWO:
+    case EKFType::TWO: {
         // use EKF to get variance
-        EKF2.getVariances(-1,velVar, posVar, hgtVar, magVar, tasVar, offset);
+        Vector2f offset;
+        EKF2.getVariances(-1, velVar, posVar, hgtVar, magVar, tasVar, offset);
         return true;
+    }
 #endif
 
 #if HAL_NAVEKF3_AVAILABLE
-    case EKFType::THREE:
+    case EKFType::THREE: {
         // use EKF to get variance
-        EKF3.getVariances(-1,velVar, posVar, hgtVar, magVar, tasVar, offset);
+        Vector2f offset;
+        EKF3.getVariances(-1, velVar, posVar, hgtVar, magVar, tasVar, offset);
         return true;
+    }
 #endif
 
 #if CONFIG_HAL_BOARD == HAL_BOARD_SITL
@@ -2079,7 +2083,6 @@ bool AP_AHRS_NavEKF::get_variances(float &velVar, float &posVar, float &hgtVar,
         hgtVar = 0;
         magVar.zero();
         tasVar = 0;
-        offset.zero();
         return true;
 #endif
     }

libraries/AP_AHRS/AP_AHRS_NavEKF.h

@@ -264,7 +264,7 @@ public:
     // indicates perfect consistency between the measurement and the EKF solution and a value of of 1 is the maximum
     // inconsistency that will be accepted by the filter
     // boolean false is returned if variances are not available
-    bool get_variances(float &velVar, float &posVar, float &hgtVar, Vector3f &magVar, float &tasVar, Vector2f &offset) const override;
+    bool get_variances(float &velVar, float &posVar, float &hgtVar, Vector3f &magVar, float &tasVar) const override;
 
     // returns the expected NED magnetic field
     bool get_mag_field_NED(Vector3f& ret) const;