F# Anonymous records support in query results

F# 4.6 added anonymous record support

These are similar to C# anonymous classes, but by design, the fields are sorted by name on creation so declaration order doesnt matter ( {| X=5; Y=6|} = {| Y=6; X=5 |} )

In dapper this create an issue when are used as a result type.

// dotnet add package Dapper

open System
open System.Data.SqlClient
open Dapper

// docker pull mcr.microsoft.com/mssql/server:2017-latest-ubuntu
// docker run -e "ACCEPT_EULA=Y" -e "SA_PASSWORD=<YourStrong!Passw0rd>" -p 1433:1433 --name sql1 -d mcr.microsoft.com/mssql/server:2017-latest-ubuntu
let connection = @"Data Source=localhost,1433;Database=master;User=sa;Password=<YourStrong!Passw0rd>;";

use db = new SqlConnection(connection)
db.Open()

// OK, same order
let res = db.QuerySingle<{| Name: string; Tid: int; X:string; Y: int |}>("select Name='fdsf', Tid=20, X='hfds', Y=15") 

// fails but understandable, different order
let res = db.QuerySingle<{| Name: string; Tid: int; X:string; Y: int |}>("select Tid=20, Name='fdsf', X='hfds', Y=15")

// fails and unexpected, same order
let res = db.QuerySingle<{| Tid: int; Name: string; X:string; Y: int |}>("select Tid=20, Name='fdsf', X='hfds', Y=15")  

the error explain it doesnt find the constructor with right shape

Unhandled Exception: System.InvalidOperationException: A parameterless default constructor or one matching signature (System.Int32 Tid, System.String Name, System.String X, System.Int32 Y) is required for <>f__AnonymousType1611086028`4'[[System.String, System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Int32, System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.String, System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Int32, System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]] materialization

As note:

// F#
let x = {| Tid = 20; Name = "fdsf"; X = "hfds"; Y = 15 |}

// IL
IL_00ea: ldstr        "fdsf"
IL_00ef: ldc.i4.s     20 // 0x14
IL_00f1: ldstr        "hfds"
IL_00f6: ldc.i4.s     15 // 0x0f
IL_00f8: newobj       instance void class '<>f__AnonymousType1611086028`4\''<string, int32, string, int32>::.ctor(!0/*string*/, !1/*int32*/, !2/*string*/, !3/*int32*/)

and

// C#
var x = new { Tid = 20, Name = "fdsf", X = "hfds", Y = 15 };

// IL
IL_0001: ldc.i4.s     20 // 0x14
IL_0003: ldstr        "fdsf"
IL_0008: ldstr        "hfds"
IL_000d: ldc.i4.s     15 // 0x0f
IL_000f: newobj       instance void class '<>f__AnonymousType0`4'<int32, string, string, int32>::.ctor(!0/*int32*/, !1/*string*/, !2/*string*/, !3/*int32*/)```

ref https://github.com/Microsoft/visualfsharp/issues/6422

Start with the supplied F# reproductions and compare their generated IL with the C# example; the report identifies constructor parameter ordering during Dapper materialization as the failing area. Done means the reordered F# anonymous-record queries materialize successfully without the constructor-shape exception.