A problem with arrays

 using UnityEngine;
 using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 
 public class GridController : MonoBehaviour {
 
     // Get closest free point in grid 
     public Vector3 snapPoint (GameObject GroundObject, Vector3 hit){
         float worldX = 2F;
         float worldY = 2F;
         float worldZ = 2F;    
         bool IsGenerated = false;
         float snap = 0.1F; 
         List<Vector3> possiblePositionsList = new List<Vector3>();
         List<Vector3> tempPositionsList = new List<Vector3>();
         List<float> distanceList = new List<float>();
         int minIndex; // Shortest distance
         float minVal;
 
         this.transform.position = hit;
         Vector3 position = this.transform.position;
         position.x = Mathf.Round(position.x / snap) * snap;
         position.y = Mathf.Round(position.y / snap) * snap;
         position.z = Mathf.Round(position.z / snap) * snap;
         this.transform.position = position;
         Vector3 gridStart = transform.position - new Vector3(worldX / 2, worldY / 2, worldZ / 2);
         for(float x =0F; x<worldX; x += snap) {
             for(float y =0F; y<worldY; y += snap) {
                 for(float z =0F; z<worldZ; z += snap) {
                     Vector3 tempPosition;
                     tempPosition = new Vector3(gridStart.x + x, gridStart.y + y, gridStart.z + z);
                     tempPositionsList.Add(tempPosition);
                 }
             }
         }
         IsGenerated = true;
 
         foreach (Vector3 tempPosition in tempPositionsList){
             GroundObject.transform.position = tempPosition;
             bool isFree = true;
                 // Check is object free space WIP
             Collider[] hitColliders = Physics.OverlapSphere(GroundObject.transform.position, GroundObject.collider.bounds.extents.magnitude);
             foreach(Collider currentCollider in hitColliders){
                 if(GroundObject.collider.bounds.Intersects(currentCollider.bounds)){
                     int adjustedTriangleCount = GroundObject.transform.GetComponent<MeshFilter>().mesh.triangles.Length / 3;
                     int otherAdjustedTriangleCount = currentCollider.transform.GetComponent<MeshFilter>().mesh.triangles.Length / 3;
                     for(int i = 0; i <= otherAdjustedTriangleCount; i ++){    // For every triangle in GroundObject...
 
                         for(int ib = 0; ib <= adjustedTriangleCount; ib ++){    // For every triangle in other object...
                             int[] aPoints = new int[3];
                             aPoints = new int[3] {GroundObject.GetComponent<MeshFilter>().mesh.triangles[(i - 1)*3 + 1], GroundObject.GetComponent<MeshFilter>().mesh.triangles[(i - 1)*3 + 2], GroundObject.GetComponent<MeshFilter>().mesh.triangles[(i - 1)*3 + 3]}; 
                             Vector3 a1 = GroundObject.transform.TransformPoint(GroundObject.GetComponent<MeshFilter>().mesh.vertices[aPoints[1]]);
                             Vector3 a2 = GroundObject.transform.TransformPoint(GroundObject.GetComponent<MeshFilter>().mesh.vertices[aPoints[2]]);
                             Vector3 a3 = GroundObject.transform.TransformPoint(GroundObject.GetComponent<MeshFilter>().mesh.vertices[aPoints[3]]);
                             int[] bPoints = new int[3];
                             bPoints = new int[3] {currentCollider.transform.GetComponent<MeshFilter>().mesh.triangles[(ib - 1)*3 + 1], currentCollider.transform.GetComponent<MeshFilter>().mesh.triangles[(ib - 1)*3 + 2], currentCollider.transform.GetComponent<MeshFilter>().mesh.triangles[(ib - 1)*3 + 3]};  
                             Vector3 b1 = currentCollider.transform.TransformPoint(currentCollider.transform.gameObject.GetComponent<MeshFilter>().mesh.vertices[aPoints[1]]);
                             Vector3 b2 = currentCollider.transform.TransformPoint(currentCollider.transform.gameObject.GetComponent<MeshFilter>().mesh.vertices[aPoints[2]]);
                             Vector3 b3 = currentCollider.transform.TransformPoint(currentCollider.transform.gameObject.GetComponent<MeshFilter>().mesh.vertices[aPoints[3]]);
                             if(TriTriOverlap.TriTriIntersect(a1, a2, a3, b1, b2, b3)){
                                 isFree = false;
                             } 
                         }
                     }
             }
             } 
             if(isFree != false){
                 possiblePositionsList.Add (tempPosition);
                 Debug.Log ("It is free!");
             }
         }
         foreach (Vector3 possiblePosition in possiblePositionsList){
             distanceList.Add(Vector3.Distance(possiblePosition, transform.position));
         } 
         minVal = distanceList.Min();
         minIndex = distanceList.IndexOf(minVal);    
         return possiblePositionsList[minIndex];
     }
 }
  

What's wrong with aPoints and bPoints? Assets/Game_scripts/GridController.cs(52,57): error CS0266: Cannot implicitly convert type System.Collections.Generic.IEnumerable' to int[]'. An explicit conversion exists (are you missing a cast?) Updated code.

EDIT: Updated code. IndexOutOfRangeException: Array index is out of range. GridController.snapPoint (UnityEngine.GameObject GroundObject, Vector3 hit) (at Assets/Game_scripts/GridController.cs:53) BuildScript.FixedUpdate () (at Assets/Game_scripts/BuildScript.cs:70)