Skip to content
GitLab
Projects Groups Topics Snippets
  • /
  • Help
    • Help
    • Support
    • Community forum
    • Submit feedback
  • Register
  • Sign in
  • GHC GHC
  • Project information
    • Project information
    • Activity
    • Labels
    • Members
  • Repository
    • Repository
    • Files
    • Commits
    • Branches
    • Tags
    • Contributor statistics
    • Graph
    • Compare revisions
    • Locked files
  • Issues 5.6k
    • Issues 5.6k
    • List
    • Boards
    • Service Desk
    • Milestones
    • Iterations
  • Merge requests 659
    • Merge requests 659
  • CI/CD
    • CI/CD
    • Pipelines
    • Jobs
    • Artifacts
    • Schedules
    • Test cases
  • Deployments
    • Deployments
    • Releases
  • Packages and registries
    • Packages and registries
    • Model experiments
  • Analytics
    • Analytics
    • CI/CD
    • Code review
    • Insights
    • Issue
    • Repository
  • Wiki
    • Wiki
  • Snippets
    • Snippets
  • Activity
  • Graph
  • Create a new issue
  • Jobs
  • Commits
  • Issue Boards
Collapse sidebar
  • Glasgow Haskell CompilerGlasgow Haskell Compiler
  • GHCGHC
  • Wiki
  • Migration
  • 8.6

8.6 · Changes

Page history
More 8.6 changes authored May 24, 2018 by Ryan Scott's avatar Ryan Scott
Hide whitespace changes
Inline Side-by-side
migration/8.6.md
View page @ 7f018dc0
......@@ -7,6 +7,30 @@ This guide summarises the changes you may need to make to your code to migrate f
## Compiler changes
### Constructor-less GADTs now require `GADTSyntax`
Data types with empty `where` clauses (such as `data T where`) are no longer valid without the `GADTSyntax` extension. (Due to an oversight, previous versions of GHC would accept them without the extension enabled.)
### `-Wincomplete-patterns` now applies to patterns in guards and `MultiWayIf`
Due to a bug, previous versions of GHC would not emit any `-Wincomplete-patterns` warnings at all for incomplete patterns inside of guards or `MultiWayIf` expressions. This bug has been fixed, which means that code like:
```
foo::Bool->Intfoo b =if| b ->1
```
Will now raise a warning in GHC 8.6:
```wiki
warning: [-Wincomplete-patterns]
Pattern match(es) are non-exhaustive
In a multi-way if alternative:
Guards do not cover entire pattern space
```
### `PolyKinds` and `TypeInType` are pickier
......
Clone repository
  • Adventures in GHC compile times
  • All things layout
  • AndreasK
  • AndreasPK
  • Back End and Run Time System
  • Backpack refactoring
  • Backpack units
  • Brief Guide for Compiling GHC to iOS
  • Building GHC on Windows with Stack protector support (SSP) (using Make)
  • CAFs
  • CafInfo rework
  • Compiling Case Expressions in ghc
  • Compiling Data.Aeson Error
  • Contributing a Patch
  • Core interface section
View All Pages