v4.8.0+ fails to compile Feliz.MaterialUI or/and Feliz.MuiX.DatePickers

[ArtemyB]

Description

When compiling a project that references Feliz.MaterialUI, Fable throws a very bloated error. Fable versions <4.8.0 compile everything fine.

Repro code

So far, I've seen the error only when I tried to compile a project that references Feliz.MaterialUI or Feliz.MuiX.DatePickers. As a ready example, the docs project in the Feliz.MaterialUI repo could be used. The steps to run it, via console, with the repo root as a working directory:

1. dotnet restore
2. cd ./docs-app/
3. pnpm install
4. pnpm start

Then, somewhere during Feliz.MaterialUI or Feliz.MuiX.DatePickers compilation, a kind of looping error will occur and clog the output. Here is a gist to the full output.

Expected and actual results

Just compile a project as it happens with Fable <=4.7.0.

Related information

• Fable version: >= 4.8.0
• Operating system: Windows 10 22H2

[ArtemyB]

I suppose the issue relates to the FCS update made in v4.8.0. Although I don't know what could provoke the error. I've checked Feliz.MaterialUI projects for the omission of the member keyword in static member definitions, and so for haven't found any.

[ArtemyB]

Seems like the origin of the problem is in that F# issue: dotnet/fsharp#17415. For now, in case of Feliz.MaterialUI packages, worked around the problem by making all the big modules (with a lot of definitions) recursive, as proposed in the mentioned issue description. But in general, for other similar cases, the issue remains unsolved as long as the originating F# issue exists.

[MangelMaxime]

Thanks for the information.

We will need to wait for F# team to fix the issue before we can include it in Fable. Hopefully, it will be done for F# 9

[ArtemyB]

Not a problem, it's already a great relief to know an actual reason and have such a simple workaround available 🙌 It was quite a luck to stumble upon the F# issue, basically a random coincidence