Commit 01ce0864 authored by kristenk's avatar kristenk Committed by GitHub
Browse files

Merge pull request #3826 from grayjay/preferences-space-leak

Fix a space leak in package preferences (part of issue #3824).
parents 00e9a094 2e5374e2
......@@ -51,17 +51,25 @@ import qualified Distribution.Solver.Modular.WeightedPSQ as W
-- | Update the weights of children under 'PChoice' nodes. 'addWeights' takes a
-- list of weight-calculating functions in order to avoid sorting the package
-- choices multiple times. Each function takes the package name, sorted list of
-- siblings' versions, and package option. 'addWeights' prepends the new
-- children's versions, and package option. 'addWeights' prepends the new
-- weights to the existing weights, which gives precedence to preferences that
-- are applied later.
addWeights :: [PN -> [Ver] -> POption -> Weight] -> Tree a -> Tree a
addWeights fs = trav go
go :: TreeF a (Tree a) -> TreeF a (Tree a)
go (PChoiceF qpn@(Q _ pn) x cs) =
let sortedVersions = L.sortBy (flip compare) $ version (W.keys cs)
weights k = [f pn sortedVersions k | f <- fs]
in PChoiceF qpn x $
W.mapWeightsWithKey (\k w -> weights k ++ w) cs
elemsToWhnf :: [a] -> ()
elemsToWhnf = foldr seq ()
in PChoiceF qpn x
-- Evaluate the children's versions before evaluating any of the
-- subtrees, so that 'sortedVersions' doesn't hold onto all of the
-- subtrees (referenced by cs) and cause a space leak.
(elemsToWhnf sortedVersions `seq`
W.mapWeightsWithKey (\k w -> weights k ++ w) cs)
go x = x
addWeight :: (PN -> [Ver] -> POption -> Weight) -> Tree a -> Tree a
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