Ormolu moves shebang from first line to the end of the file

[mavnn]

Write a simple Haskell script:

#! /usr/bin/env runhaskell
import Prelude

main :: IO ()
main = putStrLn "hello world"

Run ormolu:

import Prelude

main :: IO ()
main = putStrLn "hello world"
#! /usr/bin/env runhaskell

Is it possible to make Ormolu aware of shebang lines at the beginning of files?

[mrkkrp]

Hmm, I cannot reproduce this. I get exactly the same source code unchanged if I run Ormolu. Are you using the latest version from current master?

[mrkkrp]

Interesting, I was re-checking this today and it indeed seems to be the case, not sure what happened yesterday. I'll look into this.

[mrkkrp]

The bug was related to how we extract shebangs from sources and convert them to comments. We generate spans for those comments manually and then the normal machinery for comments renders the shebangs. Interestingly we used a fixed file name SHEBANG for shebangs (the code is partly taken from ghc-exactprint and I don't know why they do it like this there), so the way it was popped from the stream actually depended on name of input file! For example with Shebang.hs (I started with this one) the "shebang-comment" always was deemed less than any other span "SHEBANG" < "Shebang.hs" and so it was promptly popped and inserted, thus I concluded that there is no bug. When I later tried with Foo.hs I got a different result, matching yours.

[mrkkrp]

@mavnn This is now fixed, nice catch!

[mavnn]

Thank you! I hadn't even had a chance to check if it still occurred on Master (which I wasn't using direct!).

…

On Sat, 14 Sep 2019 at 15:47, Mark Karpov ***@***.***> wrote: @mavnn <https://github.com/mavnn> This is now fixed, nice catch! — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#377?email_source=notifications&email_token=AACLQQFWNAUOU3RTYKBXWRLQJT2RNA5CNFSM4IWOKYMKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD6W5FNQ#issuecomment-531485366>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AACLQQGUDQ7WSAY26IKE3JTQJT2RNANCNFSM4IWOKYMA> .

[cblp]

Not fixed:

#!/usr/bin/env stack

{-# LANGUAGE OverloadedStrings #-}

main = pure ()

is reformatted as

{-# LANGUAGE OverloadedStrings #-}

#!/usr/bin/env stack
main = pure ()

[mrkkrp]

Let's re-open this one then. Still this (and #393) is not going to make it in the first release.