GHC-9.0.1 doesn't find imported main:

Take two files: Dep.hs and bug-main.hs:

module Dep (main) where

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

and

module Main (main) where
import Dep (main)

An idiom I use, where Dep is a module in a library, and bug-main is main-is file just to make it into an executable.

GHC-8.10 (and all previous) are happy with this layout:

% ghc-8.10.3 --make bug-main.hs
[1 of 2] Compiling Dep              ( Dep.hs, Dep.o )
[2 of 2] Compiling Main             ( bug-main.hs, bug-main.o )
Linking bug-main ...

GHC-9.0.1 isn't:

% ghc-9.0.1 --make bug-main.hs 
[1 of 2] Compiling Dep              ( Dep.hs, Dep.o )
[2 of 2] Compiling Main             ( bug-main.hs, bug-main.o )

bug-main.hs:1:1: error:
    The IO action ‘main’ is not defined in module ‘Main’
  |
1 | module Main (main) where
  | ^

---

EDIT: I tried with a recent build from master, it is also affected by this.