Simon Peyton Jones pushed to branch wip/T23162-spj at Glasgow Haskell Compiler / GHC

Commits:

2 changed files:

Changes:

  • compiler/GHC/Tc/Solver/FunDeps.hs
    ... ... @@ -256,12 +256,12 @@ Consider T4254b:
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       From the ambiguity check on the type signature we get
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         [G] FD Int b
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         [W] FD Int beta
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    -  If we ineract that Wanted with /both/ the t0p-level instance, /and/ the
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    +  If we interact that Wanted with /both/ the top-level instance, /and/ the
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       local Given, we'll get
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           beta ~ Int   and     beta ~ b
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       respectively.  That would generate (b~Bool), which would fai.  I think
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       it doesn't matter which of the two we pick, but historically we have
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    -  picked teh local-fundeps firs.
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    +  picked the local-fundeps first.
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     (DFL2) Try solving from top-level instances before fundeps.
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       From the definition `foo = op` we get

  • testsuite/tests/typecheck/should_compile/tc126.hs
    ... ... @@ -35,3 +35,50 @@ g2 = f (f (f [0::Int]))
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     -- The outer f repeats the exercise, so g2::Int
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     -- This is the definition that Hugs rejects
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    +
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    +{-
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    +start iteration=0
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    +        [W] $dBug_aET {0} :: Bug (Int -> Int) a_aER[tau:1] r_aES[tau:1] (CDictCan)
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    +        [W] $dBug_aEW {0} :: Bug (Int -> Int) [r_aFd[tau:1]] a_aER[tau:1] (CDictCan)
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    +        [W] $dBug_aF0 {0} :: Bug (Int -> Int) [Int] [r_aFd[tau:1]] (CDictCan)}
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    +-->
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    +        [W] $dBug_aET {0} :: Bug (Int -> Int) a_aER[tau:1] r_aES[tau:1] (CDictCan)
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    +        [W] $dBug_aEW {0} :: Bug (Int -> Int) [r_aFd[tau:1]] a_aER[tau:1] (CDictCan)
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    +        [W] $dBug_aF0 {0} :: Bug (Int -> Int) Int r_aFd[tau:1] (CDictCan)}
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    +--> fds
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    +  a_aER := [r_aFf]
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    +  r_fD  := Int
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    +
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    +start iteration=1
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    +        [W] $dBug_aET {0} :: Bug (Int -> Int) [r_aFf[tau:1]] r_aES[tau:1] (CDictCan)
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    +        [W] $dBug_aEW {0} :: Bug (Int -> Int) [r_aFd[tau:1]] [r_aFf][tau:1]] (CDictCan)
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    +        [W] $dBug_aF0 {0} :: Bug (Int -> Int) Int Int (CDictCan)}
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    +--> (solve aF0, instance for aEW)
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    +        [W] $dBug_aET {0} :: Bug (Int -> Int) [r_aFf[tau:1]] r_aES[tau:1] (CDictCan)
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    +        [W] $dBug_aFg {1} :: Bug (Int -> Int) Int r_aFf[tau:1] (CDictCan)}
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    +--> fds
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    +  r_aES := [r_aFh]    -- fresh r_aFh
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    +  r_aFf := Int
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    +
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    +start iteration=2
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    +        [W] $dBug_aET {0} :: Bug (Int -> Int) [Int] [r_afH[tau:1]] (CDictCan)
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    +        [W] $dBug_aFg {1} :: Bug (Int -> Int) Int Int  (CDictCan)}
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    +--> (solve afG instance for aET
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    +        [W] $dBug_aFi {1} :: Bug (Int -> Int) Int r_aFh[tau:1] (CDictCan)}
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    +--> fds
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    +   f_afH := Int
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    +
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    +start iteration 3
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    +        [W] $dBug_aFi {1} :: Bug (Int -> Int) Int Int (CDictCan)}
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    +--> solve
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    +
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    +
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    +
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    +                   [W] $dBug_aCv {0} :: Bug (Int -> Int) [r_aCL[tau:1]] r_aCu[tau:1] (CDictCan)
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    +                   [W] $dBug_aEI {1} :: Bug (Int -> Int) Int            r_aCL[tau:1] (CDictCan)}
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    +-->
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    +  r_aCL := Int
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    +  r_aCu := [ r_new ]   -- r_aEJ
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    +
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    +  [W] Bug (Int -> Int) Int r_new
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    +-}

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