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Copy and update record expression doesn't compile when the record comes from a function #18062
Description
In some cases, I can't use the with keyword to copy and update a record with the F# 7 nested records shortcut syntax, when the source record comes from a function call (but in some situations it compiles fine).
It seems the compiler gets somehow confused... (?)
Repro steps
The following code doesn't compile:
type MyCustomer =
{ FirstName: string
LastName: string
Comment: string option }
type MyBooking =
{ Reference: string
Customer: MyCustomer }
type MyParentObject = { Booking: MyBooking }
module MyParentObject =
let Sample =
{ Booking =
{ Reference = "reference"
Customer =
{ FirstName = "firstname"
LastName = "lastname"
Comment = Some "comment" } } }
let okTest =
let value = MyParentObject.Sample
{ value with
MyParentObject.Booking.Customer.Comment = None }
let failingTest =
let func () = MyParentObject.Sample
{ func () with
MyParentObject.Booking.Customer.Comment = None }
More precisely, the okTest compiles ok, but the failingTest does not.
Expected behavior
I would expect the failingTest to work.
Related information
Provide any related information (optional):
I'm using Visual Studio 17.12 on Windows, with .NET 9 installed.
I reproduced the issue when targeting .NET 8 and .NET 6 too, and also from VS Code.
Did I stumble on a real issue, or am I misunderstanding something?
Activity
[-]Copy and update record expression doesn't compile when using a function output[/-][+]Copy and update record expression doesn't compile when the record comes from a function[/+]T-Gro commentedon Nov 27, 2024
It is a real issue.
The compiler has a bug and mismatches the types on the cascade of nesting.
Even when you try to eliminate access path from the left, it always comes with a different error message instead.
Also, in this case, even putting parens arond the "func()" invocation does not help.
When reducing this down to a smallest repro, this only appears when having a 3 or mor records.
When reducing the sample down to 2 records only, the nested syntax works without issues even with function invocation.
https://sharplab.io/#v2:DYLgZgzgNALiCGEC2AfA9gBwKYDsAEAygJ4QxZICwAUNdTEdngJI45YBOeAvHgN4AaIAJY4YAXzoMseALJCAJvODSevJiBZt2EqvUYB5AK5lOqmSDmLlO6spiF4SDMu58ZrtR/6uArGP+2WPYA5kEEjs5YABQAlK7hTsq0VHZ4aADWACpYpB4JkXgA7kIwABayAHRMFd48ACwATDqp8MAQaPoA0q7UeH14qWCGOADGsfERyhUyvf28Q6N448VlzDWudQDMYn2zuylBeGDwQsAiwdm5PHsDhwsjS3E8+UlU/Xz3j0Ul5TJV6/Vtu8gA==
0101 commentedon Dec 2, 2024
@kerams does this ring a bell by any chance?