bug: Adding a DuplicateField/Index to a List<T> column generates invalid code.

src/DocumentDbTests/Bugs/Bug_PR_3702_list_index_compile_error.cs

@@ -0,0 +1,48 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Marten;
+using Marten.Linq.MatchesSql;
+using Marten.Schema;
+using Marten.Testing.Harness;
+using NpgsqlTypes;
+using Weasel.Postgresql.Tables;
+using Xunit;
+
+namespace DocumentDbTests.Bugs;
+
+public class Bug_PR_3702_list_index_compile_error : BugIntegrationContext
+{
+    [Fact]
+    public async Task can_create_array_duplicate_column_on_a_list_field()
+    {
+        StoreOptions(opts =>
+        {
+            opts.RegisterDocumentType<DocWithIndexOnList>();
+        });
+
+        await theStore.Storage.ApplyAllConfiguredChangesToDatabaseAsync();
+
+        var newDoc = new DocWithIndexOnList { Id = Guid.NewGuid(), ListOfStrings = ["foo", "bar", "baz"] };
+        theSession.Store(newDoc);
+        await theSession.SaveChangesAsync();
+
+        List<string> arrayFilter = ["foo", "baz"];
+        var queriedDoc = await theSession.Query<DocWithIndexOnList>()
+            .Where(x => x.MatchesSql("d.list_of_strings @> ?", arrayFilter))
+            .FirstOrDefaultAsync();
+
+        Assert.Equal(newDoc.Id, queriedDoc.Id);
+    }
+
+    public class DocWithIndexOnList
+    {
+        public Guid Id { get; set; }
+
+        [DuplicateField(DbType = NpgsqlDbType.Array | NpgsqlDbType.Text, PgType = "text[]", IndexMethod = IndexMethod.gin)]
+        public List<string> ListOfStrings { get; set; }
+    }
+}
+
+

src/Marten/Schema/Arguments/UpsertArgument.cs

@@ -115,7 +115,7 @@ public virtual void GenerateCodeToSetDbParameterValue(GeneratedMethod method, Ge
 
             var dbTypeString = rawMemberType!.IsArray
                 ? $"{Constant.ForEnum(NpgsqlDbType.Array).Usage} | {Constant.ForEnum(PostgresqlProvider.Instance.ToParameterType(rawMemberType.GetElementType()!)).Usage}"
-                : Constant.ForEnum(DbType).Usage;
+                : $"({typeof(NpgsqlDbType).FullNameInCode()})({(int)DbType})";
 
             if (rawMemberType.IsClass || rawMemberType.IsNullable() || _members.Length > 1)
             {
@@ -179,7 +179,7 @@ public virtual void GenerateBulkWriterCodeAsync(GeneratedType type, GeneratedMet
 
         var dbTypeString = rawMemberType.IsArray
             ? $"{Constant.ForEnum(NpgsqlDbType.Array).Usage} | {Constant.ForEnum(PostgresqlProvider.Instance.ToParameterType(rawMemberType.GetElementType()!)).Usage}"
-            : Constant.ForEnum(DbType).Usage;
+            : $"({typeof(NpgsqlDbType).FullNameInCode()})({(int)DbType})";
 
 
         var memberPath = _members.Select(x => x.Name).Join("?.");