GHC plans for 8.4.1

This page is our road-map for what will be in 8.4.

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!


Release in February 2018. Cut release branch in November 2017.

Libraries Status

See Libraries and Migration/8.4.

Release highlights (planned)

Below are the major highlights of 8.4.

  • Improved support for cross-compilation (Moritz Angermann)

Build system and miscellaneous changes

  • Improved Windows support, including support for split sections and long file paths (Tamar Christina)
  • Support for building stating libraries for elf and mach-o (-staticlib)

Landed in master branch

  • Improved code generation for join points
  • Many, many bug-fixes

Library changes

Build system and miscellaneous changes

  • iserv can be used over the network via iserv-proxy
  • llvm backend uses LLVM5
  • New Shake-based build system, hadrian, will be merged. (Andrey Mokhov)
  • Remove dependency on Hoopl package. (Michal Terepeta, Phab:D3616)

Tickets marked merge with no milestone

Ticket Type Summary Priority Owner
No tickets found

Tickets slated for 8.4.1



Status: new (21 matches)

Ticket Type Summary Priority Owner
#14698 task Cut STM release highest
#14699 task Core library status for 8.4.1 highest
#14784 bug RTS header files can't be used with a C++ compiler highest hvr
#10946 bug Typed hole inside typed Template Haskell bracket causes panic high
#11196 bug TypeInType performance regressions high
#11198 bug TypeInType error message regressions high
#11371 bug Bogus in-scope set in substitutions high niteria
#11523 bug Infinite Loop when mixing UndecidableSuperClasses and the class/instance constraint synonym trick. high simonpj
#11606 bug name shadowing warnings don't trigger on standalone declarations in ghci high rwbarton
#12088 bug Type/data family instances in kind checking high
#12564 bug Type family in type pattern kind high goldfire
#13993 bug Certain inter-module specializations run out of simplifier ticks high
#14038 bug TypeApplications regression in GHC HEAD: ‘p0’ is untouchable inside the constraints: () high
#14052 bug Significant GHCi speed regression with :module and `let` in GHC 8.2.1 high
#14230 bug Gruesome kind mismatch errors for associated data family instances high goldfire
#14253 bug Pattern match checker mistakenly concludes pattern match on pattern synonym is unreachable high
#14297 bug make bindist packages the wrong binaries for cross compilers high angerman
#14441 bug GHC HEAD regression involving type families in kinds high
#14710 bug GHC 8.4.1-alpha allows the use of kind polymorphism without PolyKinds high
#14720 bug GHC 8.4.1-alpha regression with TypeInType high
#14495 feature request Relocatable GHC normal angerman


Last modified 3 weeks ago Last modified on Feb 1, 2018 6:06:34 AM