Regression: Detection of unused imports is imprecise (since GHC 8.0.1)
GHCs detection of unused imports used to be very precise. But apparently this changed with GHC 8.0.1. I already noticed for a while that there is something fishy going on and finally came up with a minimal example.
Steps to reproduce:
-- Bar.hs
module Bar (bar, module Control.Monad) where
import Control.Monad
bar :: Integer
bar = 23
-- Foo.hs
module Foo where
import Bar
import Control.Monad (forM_)
foo :: Monad m => [a] -> (a -> m ()) -> m ()
foo = forM_
baz :: Integer
baz = bar
$ ghci -Wall -Werror Foo.hs
- *Expected result:** The program is reject.
- *Actual result:** The program was reject by GHC < 8.0.1, however later versions of GHC accept the program.
Trac metadata
Trac field | Value |
---|---|
Version | 8.4.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
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Blocking | |
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Operating system | |
Architecture |