ghc-lib-parser 9.10

[amesgen]

Update to ghc-lib-parser-9.10, build with GHC 9.10.1 in CI, drop GHC 9.4, update bounds.

• See the changelog for details about the new syntactic features in GHC 9.10.
• We can remove our HasSrcSpan in favor of ghc-lib-parser's HasLoc.
• The EPA extension points in constructors do (usually) no longer contain the comments (they are now usually in the annotation part of a Located). We relied on this in p_if (as of Fix comments in if blocks #1092). Instead of laboriously passing the comments down from where we unwrap the LHsExpr, I added a new function getEnclosingComments to the R monad that leverages the comment stream, as that seemed much less invasive.
• See the review comments for some further minor points.

[github-actions]

🚀 Deployed on https://cd59744806b7d24cfd4d6e62a0941a6c6bd71f75--ormolu-live.netlify.app

[tchoutri]

I'm very excited for this PR to land, I am starting a project with GHC 9.10. :)

[mrkkrp]

Nice to see!

[brandonchinn178]

I was curious why this changed. Seems like GHC merged a change that causes signature modules to now parse Haddocks correctly. So now ghc-lib-parser returns an AST containing HsDocStringChunk " | Test line 2" instead of the previously incorrect EpaLineComment " \\| Test line 2".

However, now I see that these docs are in two places: in an EpaComments annotation and in a DocD declaration. I can't find the logic that prevents Ormolu from printing these out twice. Anyone know where that is?

[amesgen]

However, now I see that these docs are in two places: in an EpaComments annotation and in a DocD declaration.

Yeah, this has always been the case, see e.g. #901 (comment) for another example/more context.

I can't find the logic that prevents Ormolu from printing these out twice. Anyone know where that is?

It is here, specifically line 75:

ormolu/src/Ormolu/Parser/CommentStream.hs

Lines 71 to 78 in a9e996b

	-- We want to extract all comments except _valid_ Haddock comments
	rawComments0 =
	fmap (uncurry L)
	. M.toAscList
	. flip M.withoutKeys validHaddockCommentSpans
	. M.fromList
	. fmap (\(L l a) -> (l, a))
	$ allComments