Operation could destabilize the runtime when using the Grammar Explorer on any sample using VS 2019.

Hey there!

I recently saw that you updated the package for .net standard, so I wanted to try it out.

Things seem to work just fine when I build and run the project in VS2017, but when I build and run the grammar explorer in VS2019 RC1 Svc1 (latest at the time I’m logging this), I get an exception during any parse operation:

System.Security.VerificationException: Operation could destabilize the runtime.
   at Irony.Parsing.ParsingContext.ComputeStackRangeSpan(Int32 nodeCount)
   at Irony.Parsing.ReduceParserAction.GetResultNode(ParsingContext context)
   at Irony.Parsing.ReduceParserAction.Execute(ParsingContext context)
   at Irony.Parsing.Parser.ExecuteNextAction()
   at Irony.Parsing.Parser.ParseAll()
   at Irony.Parsing.Parser.Parse(String sourceText, String fileName)
   at Irony.Parsing.Parser.Parse(String sourceText)
   at Irony.WinForms.Highlighter.EditorAdapter.ParseSource(String newText) in C:\Enablon\Irony\Irony.WinForms\Highlighter\EditorAdapter.cs:line 79
   at Irony.WinForms.Highlighter.EditorAdapter.ParserLoop() in C:\Enablon\Irony\Irony.WinForms\Highlighter\EditorAdapter.cs:line 119

Given that this only happens with VS 2019, which is still in RC, I suppose this is a problem for them to fix, but I wanted to log it to make you aware.

For reference, I started the GrammarExplorer completely fresh, then loaded the Irony.Samples.dll as mentioned in the readme.

I chose the c# grammar, then typed “namespace f” in the ‘test’ tab, which immediately triggered the exception.

[dammejed]

I found the underlying issue. The difference between VS 2017 and VS 2019 is the default LangVersion selection behavior.

In VS 2017, the default is to default to the latest “major” version of the C# language, which is 7.0. In VS 2019, the default for SDK projects (which the Irony project now is), is latest “minor”, which is 7.3.

If I manually specify LangVersion 7.3 or 7.2, tests fail in both VS 2017 and VS 2019. If I manually specify LangVersion 7.1 or 7.0, tests again pass in either version of visual studio.

When I run PEVerify on a bad version of the dll, it gives me 4 errors, all related to modifying ‘initonly’ fields outside of a constructor. I guess it’s related to some optimizations that were intended to be made for readonly structs, but nothing in this project is a readonly struct, so I don’t understand why the IL would be different. Ultimately I guess it’s a bug in the C# compiler.

Seems to be caused by https://github.com/dotnet/roslyn/issues/27382.

I guess for now the solution is to either:

1. Specify <LangVersion>7.1</LangVersion> or below in the 010.Irony project. Or
2. Remove the SecurityTransparent assembly attribute from the same project.

[yallie]

To clarify, the compiler that causes the problem is already released.

Ah, so that’s worse than I thought.

Will you accept a PR for one of the above compatibility changes? Locally, I simply added <Features>peverify-compat</Features>

Sure, thank you! 👍