Fix FCS 43.10.103 API compatibility for UntypedAstUtils.fs to unblock CI

[AbhitejJohn]

CI is failing since build #20260211.6 with compilation errors in UntypedAstUtils.fs. The .NET SDK rolled forward to 10.0.103 which ships FCS 43.10.103 with breaking AST changes (LetOrUseBang/SynExprAndBang removed, NamePatPairField changed to record). This PR updates the FCS/FSharp.Core packages to 43.10.103/10.0.103, pins the SDK, and fixes the code.

[jonsequitur]

Is this consistent with the latest FSAutoComplete code?

cc @Thorium

[Thorium]

The file is here:
https://github.com/ionide/FsAutoComplete/blob/main/src/FsAutoComplete.Core/UntypedAstUtils.fs
But they have only FSharp.Core 10.0.101, not 103 yet:
https://github.com/ionide/FsAutoComplete/blob/96fabed8e9181b74e19e211717626c204c32b2c2/paket.lock#L75

Ping @TheAngryByrd

[TheAngryByrd]

Yeah FSharp.Compiler.Service makes binary incompatible changes to the AST consistently. It's something we just live with.

Is this consistent with the latest FSAutoComplete code?

As far as I know, the fork here has been out of sync with FsAutocomplete for a very long time. But we'll probably have to make the same change to patch in our repo.

[Thorium]

@TheAngryByrd I did update the files from FSAutoComplete to this repo not-long-ago to get support for function signatures etc. #4080

[AbhitejJohn]

@Thorium , @jonsequitur : Indeed, however the CI has been failing ever since with these errors:

D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\FsAutoComplete\UntypedAstUtils.fs(19,65): error FS0001: This expression was expected to have type�    'NamePatPairField'    �but here has type�    ''a * 'b * 'c' [D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\Microsoft.DotNet.Interactive.FSharp.fsproj]
D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\FsAutoComplete\UntypedAstUtils.fs(337,17): error FS0039: The constructor, module or namespace 'LetOrUseBang' is not defined. [D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\Microsoft.DotNet.Interactive.FSharp.fsproj]
D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\FsAutoComplete\UntypedAstUtils.fs(338,17): error FS0039: The value or constructor 'pat' is not defined. [D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\Microsoft.DotNet.Interactive.FSharp.fsproj]
D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\FsAutoComplete\UntypedAstUtils.fs(339,18): error FS0039: The value or constructor 'e1' is not defined. [D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\Microsoft.DotNet.Interactive.FSharp.fsproj]
D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\FsAutoComplete\UntypedAstUtils.fs(341,66): error FS0039: The value or constructor 'ands' is not defined. [D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\Microsoft.DotNet.Interactive.FSharp.fsproj]
D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\FsAutoComplete\UntypedAstUtils.fs(341,13): error FS0039: The pattern discriminator 'SynExprAndBang' is not defined. [D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\Microsoft.DotNet.Interactive.FSharp.fsproj]
D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\FsAutoComplete\UntypedAstUtils.fs(341,13): error FS0025: Incomplete pattern matches on this expression. Unmatched elements will be ignored. [D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\Microsoft.DotNet.Interactive.FSharp.fsproj]
D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\FsAutoComplete\UntypedAstUtils.fs(345,18): error FS0039: The value or constructor 'e2' is not defined. [D:\a\_work\1\s\src\Microsoft.DotNet.Interactive.FSharp\Microsoft.DotNet.Interactive.FSharp.fsproj]
    0 Warning(s)
    8 Error(s)

Here's a build link: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1298378&view=logs&j=bb592630-4b9d-53ad-3960-d954a70a95cf&t=c2e030e7-0c13-5c98-0562-982c06e545f9.

Why the PR build passed for #4080 I'm not really sure yet. This change however is LLMs proposing a fix which seems to have unblocked the build. I'd love to get your thoughts on correctness though.

[Thorium]

The reason I pinged Jimmy is that I expect he'll need the same changes to FSAutoComplete soon as well.

[AbhitejJohn]

@Thorium : Sounds good, I'm not super familiar with that integration. Would that mean we'd want to wait on those changes to be rolled out before we can merge this? Or is that independent of these updates?

[TheAngryByrd]

It's independent since FsAutocomplete here is essentially a fork. We'd just make the same changes when I get around to doing the updates.

[AbhitejJohn]

Perfect, thanks. I'll go ahead and merge this then.