What's new should tell you when a file has a conflict, even if you've 
already run 'darcs revert -a'.

See the related issue1828

I've attached a patch that implements it but it makes the whatsnew
command slower.

Quick benchmark: on my laptop, on darcs.net, without changes in the
working copy and without conflicts:

without the patch: 0.04s
with the patch: 0.14s

Is there a faster way of checking if there are conflicts in a repository?

Here goes the patch summary:

hunk ./src/Darcs/UI/Commands/WhatsNew.hs 142
+
+    r <- readRepo repo
+    Sealed res <- return $ patchsetConflictResolutions r
+    case res of
+      NilFL -> return ()
+      _ -> let cfs = nubSort $ listTouchedFiles res in
+           putDocLnWith fancyPrinters $
+             redText "Conflicts found in the following files:" $$ text
(unlines cfs)

Attachments

• resolve-issue2010_-make-whatsnew-tell-which-files-have-conflicts.dpatch

An observation of owst was to store conflicting patches data in patch index.