`quickCheckAll` ignores property with implicit parameters

[asr]

In the following example, the prop_foo property is ignored when quickCheckAll is used:

$ cat Test1.hs

{-# LANGUAGE ImplicitParams  #-}
{-# LANGUAGE TemplateHaskell #-}

import Test.QuickCheck

prop_foo :: (?y :: Int) => Int -> Bool
prop_foo x = x + ?y == ?y + x

prop_bar :: Int -> Int -> Bool
prop_bar x y = x + y == y + x

-- Template Haskell hack to make the following $quickCheckAll work
-- under GHC 7.8.
return []

-- | All tests as collected by 'quickCheckAll'.
tests :: IO Bool
tests = do
  putStrLn "Tests"
  $quickCheckAll

  where ?y = 4

And GHCi reports:

GHCi> :load Test1.hs
[1 of 1] Compiling Main             ( Test1.hs, interpreted )

Test1.hs:20:3: warning:
    Name prop_foo found in source file but was not in scope
   |
20 |   $quickCheckAll
   |   ^^^^^^^^^^^^^^

GHCi> tests
Tests
=== prop_bar from Test1.hs:9 ===
+++ OK, passed 100 tests.

True

The above example was tested with GHC 8.2.2 and QuickCheck 2.10.1.

The fix of this issue would facilitate the fix of https://github.com/agda/agda/issues/2861.

CC'ing @andreasabel.

[nick8325]

The following line of code is what does the in-scope checking:

exists <- (warning x >> return False) `recover` (reify (mkName x) >> return True)

I tried replacing reify (mkName x) with lookupValueName x, which doesn't emit a warning, but I then get this error from GHC:

Test.hs:21:3: error:
    • Can't represent implicit parameters in Template Haskell: ?y::Int
    • In the untyped splice: $quickCheckAll
   |
21 |   $quickCheckAll
   |   ^^^^^^^^^^^^^^

It looks as though GHC doesn't support reifying a function which takes implicit parameters. I can't think of any workaround for this in QuickCheck - the only thing I can suggest is using Data.Reflection instead of implicit parameters.

[MaximilianAlgehed]

I just tested this on HEAD and it now works. Closing this as completed.

[asr]

I just tested this on HEAD and it now works. Closing this as completed.

I confirm the issue was fixed (tested with GHC 9.8.2 and QuickCheck 2.14.3). Thanks!