F# code like
seq {
try
...
with
| :? SomeException as exc when (exc.InnerException :? Some2Exception)
}fails to be compiled because exc is not available in (exc.InnerException :? Some2Exception) environment.
This probably happens somewhere within part of compiler which transforms computational expressions into calls to builder.
Repro steps
Here is minimal source code with bug.
module Program
open System
// This is OK
let sample () =
try
printfn "Hi"
with
| :? AggregateException as exc when (exc.InnerException :? OperationCanceledException) ->
()
// This is OK
let asyncSample () : Async<unit> =
async {
try
printfn "Hi"
with
| :? AggregateException as exc when (exc.InnerException :? OperationCanceledException) -> ()
}
(*
** This fails with
** 0>Program.fs(26,9): Error FS0971 : Undefined value 'exc'
** 0>Program.fs(26,9): Error FS0971 : Undefined value 'exc'
** 0>Program.fs(26,9): Error FS0971 : Undefined value 'exc'
** 0>Program.fs(26,9): Error FS0971 : Undefined value 'exc'
** 0>Program.fs(26,9): Error FS0971 : Undefined value 'exc'
*)
let seqSample () : int seq =
seq {
try
printfn "Hi"
with
| :? AggregateException as exc when (exc.InnerException :? OperationCanceledException) -> ()
}
// This is OK
let seqSample2 () : int seq =
seq {
try
printfn "Hi"
with
| :? AggregateException as exc when (true) -> ()
}
[<EntryPoint>]
let main argv =
0Expected behavior
- Code compiles,
when cases of try with within seq can access exception variable;
- OR As far as I remember, F# didn't have support for
try with within seq before version 8.0. If my case is not allowed by design, then a good readable warning by compiler;
Actual behavior
Compilation fails with Undefined value 'exc'.
Related information
- dotnet version
8.0.403;
- F# version
12.8.401.0 for F# 8.0;
- Rider and Visual Studio(Ionide) code show no red lines near problematic lines;
F# code like
fails to be compiled because
excis not available in(exc.InnerException :? Some2Exception)environment.This probably happens somewhere within part of compiler which transforms computational expressions into calls to builder.
Repro steps
Here is minimal source code with bug.
Expected behavior
whencases oftry withwithinseqcan access exception variable;try withwithinseqbefore version 8.0. If my case is not allowed by design, then a good readable warning by compiler;Actual behavior
Compilation fails with
Undefined value 'exc'.Related information
8.0.403;12.8.401.0 for F# 8.0;