[Feature Request] Support C# 14

[AArnott]

When I'm using C# 14 extension members syntax, the docfx build fails with errors suggesting that my global.json selected SDK version and Directory.Build.props selected LangVersion is not being used.

Why is this? How/when can docfx support using C# 14 and/or the SDK and langversion specified by the user?

[filzrev]

docfx using Roslyn API by referencing Microsoft.CodeAnalysis.* packages.
Latest version of docfx using 4.14.0 version.

C# 14 Extensions feature support seems to be added on v5.x. (Currently preview status)
And it'll updated by PR #10859

After above PR merged.
It need to add code to handle C# 14 extensions features.

• Handle TypeKind.Extension and extract defined extensions.
• Handle AssociatedSymbol and extract information about extended method/property/user defined operator
• Add page rendering logics for extensions

[bkoelman]

I don't know if docfx shows user-defined operators, but if it does, should also take into account the new += operator which was added in C# 14.

[AArnott]

Getting a docfx release that at least doesn't totally break on C# 14 syntax would be helpful. Actually including C# 14 extension members in the docs could be a separate release, if that allows the unblocking release to come sooner.

[gumbarros]

Any ETA on this? This is affecting us to migrate to .NET 10.