#13857: compactAdd doesn't work with SmallArray# -------------------------------------+------------------------------------- Reporter: andrewthad | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.2.2 Component: Runtime System | Version: 8.2.1-rc2 Resolution: | Keywords: compact Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D3888 Wiki Page: | -------------------------------------+------------------------------------- Comment (by andrewthad): The reason why this wasn't caught earlier is that the test for compacting `SmallArray#` doesn't actually work. From D3888, we have [this test https://phabricator.haskell.org/differential/changeset/?ref=174725&whitespace =ignore-most]: {{{ import GHC.Compact import Data.Primitive.SmallArray main :: IO () main = do arr <- newSmallArray 5 (Just 'a') arr' <- compact arr print $ getCompact arr' }}} However, this fails at runtime with {{{ compact_hash_map: compaction failed: cannot compact mutable objects }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13857#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler