Fable 4.25.0 won't compile FSharpPlus anymore

Open DunetsNM opened this issue 2 months ago • 1 comments

Description

Fable 4.25.0 no longer supports Async.RunSynchronously and compilation fails on this line:

https://github.com/fsprojects/FSharpPlus/blob/e280cfe5f8f419323147f458dabc10243f04f792/src/FSharpPlus/Control/Comonad.fs#L15-L19

Not sure what a recourse should be here, maybe a runtime error in FABLE_COMPILER version as a last resort?

Known Workarounds

Fable 4.24.0 works fine.

Expected behavior

Everything compiles

Actual behavior

Compilation fails with error

FSharpPlus.1.6.1\Control\Comonad.fs(17,8): (17,32) error FABLE: Microsoft.FSharp.Control.FSharpAsync.RunSynchronously (static) is not supported by Fable

Are you willing to help with a pull-request?

Yes, but I don't know what the fix should be

Oct 29 '25 10:10 DunetsNM

@DunetsNM it looks like there is supposed to be an ifdef for Fable4 that has gotten wonky. It also looks like Fable4 hangs in CI for some reason, even though it goes fast when running it locally.

Nov 16 '25 14:11 wallymathieu