Sigh, setting ServerGC seems to kill fscyacc:

D:\a\_work\1\s\buildtools\buildtools.targets(54,5): error MSB3073: The command ""D:\a\_work\1\s\.dotnet\dotnet.exe" "D:\a\_work\1\s\artifacts\\Bootstrap\fsyacc\fsyacc.dll" -o "D:\a\_work\1\s\artifacts\obj\FSharp.Compiler.Service\Proto\netstandard2.0\pars.fs" -v --module FSharp.Compiler.Parser --open FSharp.Compiler --open FSharp.Compiler.Syntax --internal --lexlib Internal.Utilities.Text.Lexing --parslib Internal.Utilities.Text.Parsing pars.fsy" exited with code 1. [D:\a\_work\1\s\src\Compiler\FSharp.Compiler.Service.fsproj]

Build FAILED.

FSYACC : error FSY000: Object reference not set to an instance of an object. [D:\a\_work\1\s\src\Compiler\FSharp.Compiler.Service.fsproj]
D:\a\_work\1\s\buildtools\buildtools.targets(54,5): error MSB3073: The command ""D:\a\_work\1\s\.dotnet\dotnet.exe" "D:\a\_work\1\s\artifacts\\Bootstrap\fsyacc\fsyacc.dll" -o "D:\a\_work\1\s\artifacts\obj\FSharp.Compiler.Service\Proto\netstandard2.0\pars.fs" -v --module FSharp.Compiler.Parser --open FSharp.Compiler --open FSharp.Compiler.Syntax --internal --lexlib Internal.Utilities.Text.Lexing --parslib Internal.Utilities.Text.Parsing pars.fsy" exited with code 1. [D:\a\_work\1\s\src\Compiler\FSharp.Compiler.Service.fsproj]
    0 Warning(s)
    2 Error(s)

We can theoretically set it only for proto, fsharp, and visualfsharp solutions.
It will be an even worse hack though.

but this seems to kill fslex and fsyacc - there may be something we can do for that, not sure. (and should this be DOTNET_GCName=clrgc.dll cc @mangod9 )

yeah DOTNET_* is the preferred way in 6+, but both are supported atm. Perhaps your other projects are failing since they arent compiling against latest 7preview7 drop? clrgc.dll has been included only starting in preview7

We can theoretically set it only for proto, fsharp, and visualfsharp solutions.

It's that we need to set it for just fsc executions. I'll see if it can be done

@vzarytovskii I give up here - I have no idea how to get the environment variable DOTNET_gcServer=1 set only for executions of the F# compiler that comes from the .NET SDK. As usual MSBuild is the hardest thing in the universe. I guess we could execute via a batch file or similar.

Can confirm, the following command:

C:\prj\fsharp\src\Compiler> dotnet "C:\prj\fsharp\artifacts\\Bootstrap\fsyacc\fsyacc.dll" -o 
"C:\prj\fsharp\artifacts\obj\FSharp.Compiler.Service\Proto\netstandard2.0\pars.fs" -v 
--module FSharp.Compiler.Parser --open FSharp.Compiler --open FSharp.Compiler.Syntax 
--internal --lexlib Internal.Utilities.Text.Lexing --parslib Internal.Utilities.Text.Parsing pars.fsy

crashes all the time on the latest daily .net7 + server GC mode with either AVE or NRE in random places e.g.

Tested with various modes including GCStress=0xC, disabled/enabled R2R, disabled optimizations in jit - it only reproduces with gcServer=1 so sounds like a gc bug to me cc @dotnet/gc @jkotas

@EgorBo Thank you for looking at this

Here's a standalone repro, instructions are in readme: https://github.com/vzarytovskii/fsyacc-issue-repro/tree/main

Update: Turning tailcalls and optimize off does not change anything - still fails.

thanks for the repro @vzarytovskii, we will take a look (I just quickly tried and I can repro it).

I'm investigating - I suspect we are not handling mark stack overflow in Server GC correctly in this case.

@PeterSolMS Any luck with investigation? I suppose, fix will target rc2?

Sorry about not keeping this up to date - I checked in a fix, PR is here dotnet/runtime#74571.

Fix should be in RC2.