GHC plans for 8.6.1

This page is our road-map for what will be in 8.6.

If you believe your favorite thing belongs in this list, but isn't there, please yell. If it's not in the road map, it probably won't get done. Without a lot of support, many things in the road map won't get done either, so we need your help!


Cut release branch in June 2018. Release in August 2018.

Libraries Status

See Libraries? and Migration/8.6.

Release highlights (planned)

Below are the major highlights of 8.6.

Build system and miscellaneous changes

  • Improved Windows support, including support for split sections, and long file paths support (no MAX_PATH restriction) (Tamar Christina)
  • Better handling of LOAD COMMAND SIZE Limits on macOS via -dead_strip_dylibs (Moritz Angermann)

Landed in master branch

  • An early version of the GHCi :doc command
  • The core functionality of the ghc-heap-view package has been merged into GHC, allowing introspection into the structure of GHC's heap. (Patrick Dougherty, Phab:D3055)
  • Many improvements to exhausiveness checking (#14546)
  • Improvements in code generation, include a new SRT representation that results in more compact generated code (blog post)
  • Further improvements to DWARF unwinding support
  • More sophisticated constant folding (#9136)
  • StarIsType extension (proposal, Vladislav Zavialov)
  • The next phase of the MonadFail proposal, enabling the MonadFailDesugaring extension by default

Library changes

Build system and miscellaneous changes

Tickets marked merge with no milestone

Ticket Type Summary Priority Owner
No tickets found

Tickets slated for 8.6.1



Status: new (76 matches)

Ticket Type Summary Priority Owner
#15541 bug package environment files and the GHC API highest
#15084 bug Functions in HsUtils don't have the most general type high
#15275 bug AArch64 validation fails with many invalid relocations high
#15287 bug T11627[ab] fail on some Darwin environments high
#15304 bug Huge increase of compile time and memory use from 8.0.2 to 8.2.2 or 8.4.2 high tdammers
#15350 bug gcdExtInteger violates assertion high
#15567 bug security of package environment files high
#15399 bug Build failure on PowerPC 64-bit big endian normal trommler
#15493 feature request Elide empty dictionaries normal
#15498 bug HPC: do notation marks () as non-covered normal
#15504 bug -XStrict doesn't prevent warnings from -Wunbanged-strict-patterns normal
#15512 feature request Rewrite rules should be able to produce custom compiler errors normal
#15513 feature request How to pass "-hide-all-packages" to the GHC API? normal
#15521 feature request Provide a strict version of sum normal
#15522 bug Cannot bind symbolic names in a rule normal
#15524 bug Performance regression when using the GHC API to evaluate code compared to 8.4 normal
#15531 bug CApiFFI generates bad prototypes for pointers of `Foreign.C` types normal
#15532 feature request Relaxing Levity-Polymorphic Binder Check for Lifted vs Unlifted pointers normal
#15533 feature request Access the number of bits in the target machine's Int type at compile time normal
#15540 bug GHCi does not follow the XDG Base Directory Specification normal
#15546 feature request Display coaxiom branch incompatibilities in GHCi normal mniip
#15547 feature request A function `nat2Word# :: KnownNat n => Proxy# n -> Word#` normal
#15553 bug GHC.IO.Encoding not flushing partially converted input normal
#15554 bug COMPLETE pragmas make overlapping-patterns warnings behave oddly normal
#15557 feature request Reduce type families in equations' RHS when testing equation compatibility normal
#15561 bug TypeInType: Type error conditioned on ordering of GADT and type family definitions normal
#15562 bug `-XStrict -XNoStrict` is not neutral normal
#15565 feature request ancient ghc release history on web page is incomplete normal
#15570 bug Core transformations generate bad indexCharOffAddr# call normal alpmestan
#15573 task Make bindings with multiple occurrences a join point instead of duplicating code during inlining. normal
#15574 bug C wrappers for Haskell foreign exports don't have finalizers (causes memory leak). normal
#15576 bug Hadrian puts its build tree in the wrong place normal
#15580 task Specialize min/max functions for GHC provided instances. normal
#15582 bug Phabricator shows "drafts" by default normal bgamari
#15587 bug traceEvent tests failing in slow validate normal osa1
#15588 bug Panic when abusing kind inference normal
#15589 bug Always promoting metavariables during type inference may be wrong normal
#15595 bug Stack overflow in withArgs leads to infinite memory-consuming loop normal
#15602 bug PAP invariant of pointer tagging does not hold in profiling builds normal
#15603 bug ref6 example from StaticPointers documentation doesn't type check normal
#15605 bug Documentation of atomicModifyMutVar# does not show properly normal
#15606 bug Don't float out lets in between lambdsa normal
#15612 bug Got Unable to commit 16777216 bytes of memory error on Ubuntu normal
#15616 bug Bug when using TimerManager/GHC.Event ? normal
#15617 bug Unboxed tuples/sum error message on `a = show 5` in expression evaluation and interactive modes normal JulianLeviston
#15619 bug List comprehension seems to prevent some rewrite rules to fire normal
#15620 bug Speed up Data.Unique normal
#15622 feature request Generalize `E{0,1,2,3,6,9,12}` from `Data.Fixed` normal rockbmb
#15626 bug Optimise wakeups for STM normal
#15632 bug Undependable Dependencies normal
#15639 bug Surprising failure combining QuantifiedConstraints with Coercible normal
#15646 bug ghci takes super long time to find the type of large fractional number normal JulianLeviston
#15650 feature request Add (or document if already exist) ability to derive custom typeclasses via source plugins normal
#15655 bug Simpliify tcTyConScopedTyVars normal
#15657 feature request Support promotion of pattern synonyms to kinds normal
#15661 bug Nullary constraint in GHCi breaks `:t` command normal
#15663 bug T9675 inexplicably regressed in allocations due to text submodule bump normal alpmestan
#15665 feature request Break up the stable pointer table normal
#15668 bug Allocations values for some compile tests are way too hight normal
#15670 bug FloatFnInverses seems to show some weird rounding/precision issues. normal
#15672 bug Flags missing documentation. normal
#15674 feature request GADT's displayed type is misleading normal
#15676 bug Users guide: broken external links normal
#15679 bug Use String rather than [Char] where possible normal
#15680 bug Flag for printing absolute paths in diagnostics normal
#15682 bug evolve / improve Native Gen Format in Format.hs (especially in context of post simd cleanup) normal
#15683 bug coerce fails for Coercible type families normal
#15684 bug Add tests for SIMD loads and stores normal
#15687 feature request Type synonym unused binds no warning? normal
#15689 bug s390x builds flood with -Wunused-label warnings normal
#15693 bug Abstracting out pattern into a pattern synonym fails with scary error normal
#15697 bug Typed holes inferring a more polymorphic type normal
#15699 bug Run sanity checker in more testsuite runs normal bgamari
#15705 bug Confusing parser error in 8.6 normal
#15707 feature request More liberally kinded coercions for newtypes normal
#15698 task SingleEntry update flag for Stg bindings is not used lowest


Last modified 15 months ago Last modified on Oct 5, 2018 9:59:27 PM