Release-only InvalidProgramException: Seq.collect over a struct collection (ImmutableArray) materialised with List.ofSeq

[charlesroddie]

Seq.collect whose 'Collection type parameter is instantiated to a struct collection (e.g. ImmutableArray<T>), materialised with List.ofSeq/Seq.toList, produces invalid IL under release optimization.

Repro

module Repro

open System
open System.Collections.Immutable

let f() = [ ImmutableArray.Create(1, 2) ] |> Seq.collect id |> List.ofSeq

[<EntryPoint>]
let main _ =
    Console.WriteLine((f()).Length)
    0

dotnet run -c Debug prints 2. dotnet run -c Release:

Unhandled exception. System.InvalidProgramException: Common Language Runtime detected an invalid program.
   at Repro.f()

Environment

• .NET SDK 10.0.302
• FSharp.Core 10.1.300
• net10.0, Windows 11 x64