Hi Brandon, On Sun, Mar 17, 2019 at 2:09 PM Brandon Allbery wrote:

No contradiction: "not those that are imported" means a module which imports names does not automatically re-export those names to other modules that import it. So T does indeed export "main", which is imported unqualified by Main

No argument with anything said there.

and thereby causes an ambiguous occurrence.

This I don't get. I presume the ambiguous occurrence is due to the question what `main` is `Main.hs` exporting (or in this case is the "entry-point" for the program)? My reading of the above is that only the local `main` can be exported (or again, in this case, "considered" for the "entry-point") so where is the ambiguity? -- Shayne Fletcher Language Engineer c: +1 917 699 7763 e: shayne.fletcher@daml.com Digital Asset Holdings, LLC 4 World Trade Center 150 Greenwich Street, 47th Floor https://maps.google.com/?q=150+Greenwich+Street,+47th+Floor%C2%A0+%C2%A0+%C2%A0+%C2%A0+%C2%A0+New+York,+NY+10007,+USA&entry=gmail&source=g New York, NY 10007, USA https://maps.google.com/?q=150+Greenwich+Street,+47th+Floor%C2%A0+%C2%A0+%C2%A0+%C2%A0+%C2%A0+New+York,+NY+10007,+USA&entry=gmail&source=g digitalasset.com http://www.digitalasset.com/ -- This message, and any attachments, is for the intended recipient(s) only, may contain information that is privileged, confidential and/or proprietary and subject to important terms and conditions available at  http://www.digitalasset.com/emaildisclaimer.html http://www.digitalasset.com/emaildisclaimer.html. If you are not the intended recipient, please delete this message.

On Sun, Mar 17, 2019 at 2:23 PM Brandon Allbery wrote:

Hm. You're probably right that it should only consider the locally defined one,

Cool.

but I can see why it would do this

Can you elaborate? Perhaps,

and wonder if there's even a good way to constrain that check currently.

indicates that you can see why it might be so based on knowledge of the implementation? -- Shayne Fletcher Language Engineer c: +1 917 699 7763 e: shayne.fletcher@daml.com Digital Asset Holdings, LLC 4 World Trade Center 150 Greenwich Street, 47th Floor https://maps.google.com/?q=150+Greenwich+Street,+47th+Floor%C2%A0+%C2%A0+%C2%A0+%C2%A0+%C2%A0+New+York,+NY+10007,+USA&entry=gmail&source=g New York, NY 10007, USA https://maps.google.com/?q=150+Greenwich+Street,+47th+Floor%C2%A0+%C2%A0+%C2%A0+%C2%A0+%C2%A0+New+York,+NY+10007,+USA&entry=gmail&source=g digitalasset.com http://www.digitalasset.com/ -- This message, and any attachments, is for the intended recipient(s) only, may contain information that is privileged, confidential and/or proprietary and subject to important terms and conditions available at  http://www.digitalasset.com/emaildisclaimer.html http://www.digitalasset.com/emaildisclaimer.html. If you are not the intended recipient, please delete this message.

On Mon, Mar 18, 2019 at 9:30 PM Ben Gamari wrote:

Shayne Fletcher via ghc-devs writes:

...

Consider this two file program: ``` module T where main = undefined

module Main where import T main = putStrLn "Hello world!" ```

Both 8.4.3 and 8.6.3 agree: ``` Main.hs:1:1: error: Ambiguous occurrence ‘main’ It could refer to either ‘T.main’, imported from ‘T’ at Main.hs:2:1-8 (and originally defined at Main.hs:2:1-4) or ‘Main.main’, defined at Main.hs:5:1 ```

Is this expected behavior? Does it not contradict "If the export list is omitted, all values, types and classes defined in the module are exported, but not those that are imported" ( https://www.haskell.org/onlinereport/haskell2010/haskellch5.html)? If the latter, is this a bug? What am I missing?

The language you cite from the report makes it sound as though this is a bug. Can you open a ticket?

Yes! Tracked in https://gitlab.haskell.org/ghc/ghc/issues/16453. -- Shayne Fletcher Language Engineer c: +1 917 699 7763 e: shayne.fletcher@daml.com Digital Asset Holdings, LLC 4 World Trade Center 150 Greenwich Street, 47th Floor https://maps.google.com/?q=150+Greenwich+Street,+47th+Floor%C2%A0+%C2%A0+%C2%A0+%C2%A0+%C2%A0+New+York,+NY+10007,+USA&entry=gmail&source=g New York, NY 10007, USA https://maps.google.com/?q=150+Greenwich+Street,+47th+Floor%C2%A0+%C2%A0+%C2%A0+%C2%A0+%C2%A0+New+York,+NY+10007,+USA&entry=gmail&source=g digitalasset.com http://www.digitalasset.com/ -- This message, and any attachments, is for the intended recipient(s) only, may contain information that is privileged, confidential and/or proprietary and subject to important terms and conditions available at  http://www.digitalasset.com/emaildisclaimer.html http://www.digitalasset.com/emaildisclaimer.html. If you are not the intended recipient, please delete this message.