Adds MAC address (macaddr and macaddr8) functions for translation

- Maps macaddr and macaddr8 functions to CLR extension methods.
  - macaddr: https://www.postgresql.org/docs/current/static/functions-net.html#MACADDR-FUNCTIONS-TABLE
  - macaddr8: https://www.postgresql.org/docs/current/static/functions-net.html#MACADDR8-FUNCTIONS-TABLE

- Includes functional tests covering translation.

- TODO:
  - Map the standard relational operators and bitwise arithmetic operators.

src/EFCore.PG/Extensions/NpgsqlNetworkAddressExtensions.cs

@@ -24,6 +24,7 @@
 #endregion
 
 using System.Net;
+using System.Net.NetworkInformation;
 using JetBrains.Annotations;
 using Npgsql.EntityFrameworkCore.PostgreSQL.Utilities;
 
@@ -799,5 +800,31 @@ public static class NpgsqlNetworkAddressExtensions
         /// This method is only intended for use via SQL translation as part of an EF Core LINQ query.
         /// </exception>
         public static (IPAddress Address, int Subnet) Merge([CanBeNull] this DbFunctions _, (IPAddress Address, int Subnet) cidr, (IPAddress Address, int Subnet) other) => throw new ClientEvaluationNotSupportedException();
+
+        /// <summary>
+        /// Sets the last 3 bytes of the MAC address to zero. For macaddr8, the last 5 bytes are set to zero.
+        /// </summary>
+        /// <param name="_">The <see cref="DbFunctions"/> instance.</param>
+        /// <param name="macAddress">The MAC address to truncate.</param>
+        /// <returns>
+        /// The MAC address with the last 3 bytes set to zero. For macaddr8, the last 5 bytes are set to zero.
+        /// </returns>
+        /// <exception cref="ClientEvaluationNotSupportedException">
+        /// This method is only intended for use via SQL translation as part of an EF Core LINQ query.
+        /// </exception>
+        public static PhysicalAddress Truncate([CanBeNull] this DbFunctions _, PhysicalAddress macAddress) => throw new ClientEvaluationNotSupportedException();
+
+        /// <summary>
+        /// Sets the 7th bit to one, also known as modified EUI-64, for inclusion in an IPv6 address.
+        /// </summary>
+        /// <param name="_">The <see cref="DbFunctions"/> instance.</param>
+        /// <param name="macAddress">The MAC address to modify.</param>
+        /// <returns>
+        /// The MAC address with the 7th bit set to one.
+        /// </returns>
+        /// <exception cref="ClientEvaluationNotSupportedException">
+        /// This method is only intended for use via SQL translation as part of an EF Core LINQ query.
+        /// </exception>
+        public static PhysicalAddress Set7BitMac8([CanBeNull] this DbFunctions _, PhysicalAddress macAddress) => throw new ClientEvaluationNotSupportedException();
     }
 }

src/EFCore.PG/Query/ExpressionTranslators/Internal/NpgsqlNetworkAddressTranslator.cs

@@ -25,6 +25,7 @@
 
 using System.Linq.Expressions;
 using System.Net;
+using System.Net.NetworkInformation;
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Query.ExpressionTranslators;
@@ -130,6 +131,12 @@ public Expression Translate(MethodCallExpression expression)
             case nameof(NpgsqlNetworkAddressExtensions.Merge):
                 return new PgFunctionExpression("inet_merge", typeof((IPAddress Address, int Subnet)), new[] { expression.Arguments[1], expression.Arguments[2] });
 
+            case nameof(NpgsqlNetworkAddressExtensions.Truncate):
+                return new PgFunctionExpression("trunc", typeof(PhysicalAddress), new[] { expression.Arguments[1] });
+
+            case nameof(NpgsqlNetworkAddressExtensions.Set7BitMac8):
+                return new PgFunctionExpression("macaddr8_set7bit", typeof(PhysicalAddress), new[] { expression.Arguments[1] });
+
             default:
                 return null;
             }

src/EFCore.PG/Storage/Internal/Mapping/NpgsqlNetworkTypeMappings.cs

@@ -50,7 +50,7 @@ protected override string GenerateNonNullSqlLiteral(object value)
 
     public class NpgsqlMacaddr8TypeMapping : NpgsqlTypeMapping
     {
-        public NpgsqlMacaddr8TypeMapping() : base("macaddr8", typeof(PhysicalAddress), NpgsqlDbType.MacAddr) { }
+        public NpgsqlMacaddr8TypeMapping() : base("macaddr8", typeof(PhysicalAddress), NpgsqlDbType.MacAddr8) { }
 
         protected NpgsqlMacaddr8TypeMapping(RelationalTypeMappingParameters parameters, NpgsqlDbType npgsqlDbType)
             : base(parameters, npgsqlDbType) { }

test/EFCore.PG.FunctionalTests/Query/NetworkAddressQueryNpgsqlTest.cs

@@ -1,7 +1,9 @@
 using System;
 using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
 using System.Linq;
 using System.Net;
+using System.Net.NetworkInformation;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.TestUtilities;
 using Microsoft.Extensions.DependencyInjection;
@@ -630,6 +632,45 @@ public void ValueTuple_cidr_Merge()
             }
         }
 
+        /// <summary>
+        /// Tests translation for <see cref="NpgsqlNetworkAddressExtensions.Truncate(DbFunctions,PhysicalAddress)"/>.
+        /// </summary>
+        [Fact]
+        public void PhysicalAddress_macaddr_Truncate()
+        {
+            using (NetContext context = Fixture.CreateContext())
+            {
+                var _ =
+                    context.NetTestEntities
+                           .Select(
+                               x => new
+                               {
+                                   macaddr = EF.Functions.Truncate(x.Macaddr),
+                                   macaddr8 = EF.Functions.Truncate(x.Macaddr8)
+                               })
+                           .ToArray();
+
+                AssertContainsSql("SELECT trunc(x.\"Macaddr\") AS macaddr, trunc(x.\"Macaddr8\") AS macaddr8");
+            }
+        }
+
+        /// <summary>
+        /// Tests translation for <see cref="NpgsqlNetworkAddressExtensions.Set7BitMac8(DbFunctions,PhysicalAddress)"/>.
+        /// </summary>
+        [Fact]
+        public void PhysicalAddress_macaddr_Set7BitMac8()
+        {
+            using (NetContext context = Fixture.CreateContext())
+            {
+                PhysicalAddress[] _ =
+                    context.NetTestEntities
+                           .Select(x => EF.Functions.Set7BitMac8(x.Macaddr8))
+                           .ToArray();
+
+                AssertContainsSql("SELECT macaddr8_set7bit(x.\"Macaddr8\")");
+            }
+        }
+
         #endregion
 
         #region Fixtures
@@ -733,6 +774,17 @@ public class NetTestEntity
             /// The network address.
             /// </summary>
             public (IPAddress Address, int Subnet) Cidr { get; set; }
+
+            /// <summary>
+            /// The MAC address.
+            /// </summary>
+            public PhysicalAddress Macaddr { get; set; }
+
+            /// <summary>
+            /// The MAC address.
+            /// </summary>
+            [Column(TypeName = "macaddr8")]
+            public PhysicalAddress Macaddr8 { get; set; }
         }
 
         /// <summary>