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

Tickets slated for 8.6.1


Status: merge (3 matches)

Ticket Type Summary Priority Differential Rev(s) Owner
#15475 bug Plugin recompilation check still panics highest Phab:D5048
#15492 bug Plugin recompilation check fails when profiling is enabled highest Phab:D5048
#15527 bug TypeApplications error message doesn't parenthesize infix name normal Phab:D5071

Status: patch (4 matches)

Ticket Type Summary Priority Differential Rev(s) Owner
#15350 bug gcdExtInteger violates assertion high Phab:D5042 Bodigrim
#15482 bug the_gc_thread variable from GC.c is not aligned to 64 normal Phab:D5052
#15529 bug runtime bug when profiling retainers normal Phab:D5075
#15538 bug GHC boot script can't handle Git remote not named origin normal Phab:D5077 ChaiTRex

Status: upstream (1 match)

Ticket Type Summary Priority Differential Rev(s) Owner
#15494 bug Cannot install GHC through stack on NixOS normal


Status: new (42 matches)

Ticket Type Summary Priority Owner
#14899 bug Significant compilation time regression between 8.4 and HEAD due to coverage checking highest
#15112 bug ghc 8.4.2 on OS X: clang: warning: argument unused during compilation: '-nopie' highest
#15176 bug Superclass `Monad m =>` makes program run 100 times slower highest bgamari
#15293 task Set up staging branch highest bgamari
#15390 task Figure out why CircleCI isn't generating haddocks highest bgamari
#15473 bug GHC 8.6+ loops infinitely on an UndecidableInstances error message highest
#15519 bug Minor code refactoring leads to drastic performance degradation highest
#14506 bug Configure Harbormaster to trigger CircleCI builds high alpmestan
#15059 bug ghcpkg05 fails high
#15084 bug Functions in HsUtils don't have the most general type high
#15274 bug Numerous validation failures when building GHC with LLVM 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
#15442 bug GhcStage3HcOpts passed to ghc-stage1 high
#15444 bug 8.4.3 has an undocumented dependency on libnuma. high
#15488 bug GHC takes up huge amount of memory when compiling accelerate 1.2.0 high
#15541 bug package environment files and the GHC API high
#15485 bug GHC uses 300% CPU when calling into blocking C call normal
#15487 bug "Ambiguos occurrence" error message uses strange qualification normal
#15493 feature request Elide empty dictionaries normal
#15498 bug HPC: do notation marks () as non-covered normal
#15502 bug -ddump-splices truncates Integer literals to Int literals normal
#15504 bug -XStrict doesn't prevent warnings from -Wunbanged-strict-patterns normal
#15505 bug Assertion failures in tests T7224, T9201, LevPolyBounded normal
#15508 bug concprog001 fails with various errors when compiled with -prof normal
#15509 bug `showEFloat` inconsistency introduced in base-4.12 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
#15516 bug ghci: dynamic linking fails on osx normal
#15517 bug -O0 and pattern synonyms triggers panic in trimJoinCont 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
#15539 bug Regression since 7.10.3, "variable not in scope" errors sometimes get buried under a sea of much less relevant errors. normal
#15540 bug GHCi does not follow the XDG Base Directory Specification normal
#15542 bug DuplicateRecordFields not honored within a data family? normal
#15503 bug interpreter: sequence_ (replicate 100000000 (return ())) gobbles up memory low
#15510 feature request Qualified Holes low


Ticket Type Summary Priority Owner
No tickets found

Last modified 9 days ago Last modified on Aug 11, 2018 2:24:56 AM