Crash in VS for files containing large pattern matches

[Happypig375]

Repro steps

1. Checkout https://github.com/Happypig375/fsharp/tree/f20da155c31c90df62a526493757d5f3ce13cc3e
2. Open FSharp.Compiler.Service.sln
3. Open src/fsharp/FSharp.Core/Linq.fs
4. Wait for typechecking
5. VS crashes

Expected behavior

VS does not crash and typecheck successfully

Actual behavior
VS crashes before typechecking is done.

Known workarounds

97a8708 seems to have solved it.

Related information

Microsoft Visual Studio Community 2019
Version 16.10.3
VisualStudio.16.Release/16.10.3+31424.327
Microsoft .NET Framework
Version 4.8.04084

Installed Version: Community

Visual C++ 2019   00435-60000-00000-AA759
Microsoft Visual C++ 2019

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ASA Service Provider   1.0

ASP.NET and Web Tools 2019   16.10.526.50910
ASP.NET and Web Tools 2019

ASP.NET Web Frameworks and Tools 2019   16.10.526.50910
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Azure App Service Tools v3.0.0   16.10.526.50910
Azure App Service Tools v3.0.0

Azure Data Lake Node   1.0
This package contains the Data Lake integration nodes for Server Explorer.

Azure Data Lake Tools for Visual Studio   2.6.3000.0
Microsoft Azure Data Lake Tools for Visual Studio

Azure Stream Analytics Tools for Visual Studio   2.6.3000.0
Microsoft Azure Stream Analytics Tools for Visual Studio

C# Tools   3.10.0-4.21318.11+7ceb633154acb9d716fd3eb2b6df1a0468d8e416
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Common Azure Tools   1.10
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Dotfuscator Community Edition   6.3.0+8b29d6f4a2
PreEmptive Protection - Dotfuscator CE

Extensibility Message Bus   1.2.6 (master@34d6af2)
Provides common messaging-based MEF services for loosely coupled Visual Studio extension components communication and integration.

IntelliCode Extension   1.0
IntelliCode Visual Studio Extension Detailed Info

Microsoft Azure HDInsight Azure Node   2.6.3000.0
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Microsoft Azure Hive Query Language Service   2.6.3000.0
Language service for Hive query

Microsoft Azure Stream Analytics Language Service   2.6.3000.0
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Microsoft Azure Stream Analytics Node   1.0
Azure Stream Analytics Node under Azure Node

Microsoft Azure Tools   2.9
Microsoft Azure Tools for Microsoft Visual Studio 2019 - v2.9.40423.1

Microsoft Continuous Delivery Tools for Visual Studio   0.4
Simplifying the configuration of Azure DevOps pipelines from within the Visual Studio IDE.

Microsoft JVM Debugger   1.0
Provides support for connecting the Visual Studio debugger to JDWP compatible Java Virtual Machines

Microsoft Library Manager   2.1.113+g422d40002e.RR
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Microsoft Visual C++ Wizards   1.0
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Microsoft Visual Studio Tools for Containers   1.2
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Microsoft Visual Studio VC Package   1.0
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Mono Debugging for Visual Studio   16.10.15 (552afdf)
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Node.js Tools   1.5.30310.1 Commit Hash:e550dd1b679956810ccace4368dbc7a64443213b
Adds support for developing and debugging Node.js apps in Visual Studio

NuGet Package Manager   5.10.0
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ProjectServicesPackage Extension   1.0
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Razor (ASP.NET Core)   16.1.0.2122504+13c05c96ea6bdbe550bd88b0bf6cdddf8cde1725
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SQL Server Data Tools   16.0.62106.24090
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ToolWindowHostedEditor   1.0
Hosting json editor into a tool window

TypeScript Tools   16.0.30429.2002
TypeScript Tools for Microsoft Visual Studio

Visual Basic Tools   3.10.0-4.21318.11+7ceb633154acb9d716fd3eb2b6df1a0468d8e416
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Visual F# Tools   16.10.0-beta.21262.7+1b23bbeda88ea3cb9be9af777f4c99fa8663df81
Microsoft Visual F# Tools

Visual Studio Code Debug Adapter Host Package   1.0
Interop layer for hosting Visual Studio Code debug adapters in Visual Studio

Visual Studio Container Tools Extensions   1.0
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Visual Studio Tools for Containers   1.0
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Visual Studio Tools for Unity   4.10.3.0
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VisualStudio.DeviceLog   1.0
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VisualStudio.Foo   1.0
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Xamarin   16.10.000.234 (d16-10@ecaf29b)
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Xamarin Designer   16.10.0.115 (remotes/origin/c750fbf1bde3c720d077f51640fe197c6dac7cbe@c750fbf1b)
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Xamarin Templates   16.10.5 (355b57a)
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Xamarin.Android SDK   11.3.0.4 (d16-10/ae14caf)
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    Xamarin.Android Tools: xamarin/xamarin-android-tools/d16-10@c5732a0


Xamarin.iOS and Xamarin.Mac SDK   14.20.0.24 (c4b89cddb)
Xamarin.iOS and Xamarin.Mac Reference Assemblies and MSBuild support.

[dsyme]

@Happypig375 Some very large disjuctive pattern matches involving active patterns do cause problems for compilation. I do wonder if this is a new variation on this issue.

In any case, could you submit that change as a PR?

thanks

[Happypig375]

@dsyme The workaround in the commit just added extra ->s to the disjunctive pattern to the PR of #11681 such that the pattern is broken apart, which isn't actually a fix.

[dsyme]

@dsyme The workaround in the commit just added extra ->s to the disjunctive pattern to the PR of #11681 such that the pattern is broken apart, which isn't actually a fix.

Yes, I'd still like to see that submitted, so we can decouple the editability of Linq.fs from any future fix. If you could also put together a standalone repro for the issue in terms of an independent project that would be great.

@TIHan It's worth checking if we haven't regressed this

[Happypig375]

@dsyme It's not a problem of the file on main, it's encountered while changing its contents in #11681.

[dsyme]

@dsyme It's not a problem of the file on main, it's encountered while changing its contents in #11681.

OK, I see, thanks

[dsyme]

This will be fixed by #11993 and I'll consider it covered by the other bugs covered by that PR