[ambiguous occurrence bug?]

[Brandon Allbery]

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 and thereby causes an ambiguous occurrence. But if T
had imported "main" from a third module, it would not be exported for Main
to import unless the export from T was explicit.

On Sun, Mar 17, 2019 at 1:50 PM Shayne Fletcher via ghc-devs <
ghc-devs at haskell.org> wrote:

> Sorry in advance if I should be posting questions of this kind elsewhere
> (please tell me if so!).
>
> 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?
>
> --
> Shayne Fletcher
> Language Engineer
> c: +1 917 699 7763
> e: shayne.fletcher at daml.com
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-- 
brandon s allbery kf8nh
allbery.b at gmail.com
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