I don't understand how ignoring version in the VFS help us here🤔

Because cabal only works with the physical file system. If the VFS changes, then cabal simply can't perform a reload, ascabal repl will still observe the same.cabal file. That's why we only want to invalidate the shake session, if the.cabal file on disk has been modified.

Further, let's have a look atgetModificationTimeImpl:

getModificationTimeImpl::Bool->NormalizedFilePath->Action (MaybeBS.ByteString, ([FileDiagnostic],MaybeFileVersion))getModificationTimeImpl missingFileDiags file=dolet file'= fromNormalizedFilePath filelet wrap time= (Just$LBS.toStrict$B.encode$toRational time, ([],Just$ModificationTime time))    mbVf<- getVirtualFile filecase mbVfofJust (virtualFileVersion-> ver)->do            alwaysRerunpure (Just$LBS.toStrict$B.encode ver, ([],Just$VFSVersion ver))Nothing->do            isWF<- use_AddWatchedFile fileif isWFthen-- the file is watched so we can rely on FileWatched notifications,-- but also need a dependency on IsFileOfInterest to reinstall-- alwaysRerun when the file becomes VFS                    void (use_IsFileOfInterest file)elseif isInterface filethen-- interface files are tracked specially using the closed world assumptionpure()else-- in all other cases we will need to freshly check the file system                        alwaysRerun...

First, we don't care about theisInterface file check. Then, if the file isn't open in the VFS, we will never rerun this rule, unless theIsFileOfInterest rule is marked dirty, which it never will for.cabal files.

In my understanding,isWF will beTrue for.cabal files.

Thanks for the explanation, much clear to me now.

If I am not mistaken,GetPhysicalModificationTime is for.cabal files?
andcfps' are mostly.hs file locations, and we are type checking those files here.

But I do not really know how we handle.cabal file in HLS and where we callGetModificationTime for.cabal files.

Good catch, this is wrong, it should beGetModificationTime