Skip to content

GitLab

  • Projects
  • Groups
  • Snippets
  • Help
    • Loading...
  • Help
    • Help
    • Support
    • Community forum
    • Submit feedback
  • Sign in / Register
GHC
GHC
  • Project overview
    • Project overview
    • Details
    • Activity
    • Releases
  • Repository
    • Repository
    • Files
    • Commits
    • Branches
    • Tags
    • Contributors
    • Graph
    • Compare
    • Locked Files
  • Issues 4,260
    • Issues 4,260
    • List
    • Boards
    • Labels
    • Service Desk
    • Milestones
    • Iterations
  • Merge Requests 398
    • Merge Requests 398
  • Requirements
    • Requirements
    • List
  • CI / CD
    • CI / CD
    • Pipelines
    • Jobs
    • Schedules
  • Security & Compliance
    • Security & Compliance
    • Dependency List
    • License Compliance
  • Operations
    • Operations
    • Incidents
    • Environments
  • Analytics
    • Analytics
    • CI / CD
    • Code Review
    • Insights
    • Issue
    • Repository
    • Value Stream
  • Wiki
    • Wiki
  • Snippets
    • Snippets
  • Members
    • Members
  • Collapse sidebar
  • Activity
  • Graph
  • Create a new issue
  • Jobs
  • Commits
  • Issue Boards
  • Glasgow Haskell Compiler
  • GHCGHC
  • Merge Requests
  • !1055

Closed
Opened May 29, 2019 by Ömer Sinan Ağacan@osa1Maintainer
  • Report abuse
Report abuse

Check out, review, and merge locally

Step 1. Fetch and check out the branch for this merge request

git fetch "https://gitlab.haskell.org/osa1/ghc.git" "fix_t16066"
git checkout -b "osa1/ghc-fix_t16066" FETCH_HEAD

Step 2. Review the changes locally

Step 3. Merge the branch and fix any conflicts that come up

git fetch origin
git checkout "master"
git merge --no-ff "osa1/ghc-fix_t16066"

Step 4. Push the result of the merge to GitLab

git push origin "master"

Note that pushing to GitLab requires write access to this repository.

Tip: You can also checkout merge requests locally by following these guidelines.

Fix arity type of coerced types in CoreArity

  • Overview 10
  • Commits 1
  • Pipelines 4
  • Changes 4

Previously if we had

f |> co

where f had arity type ABot N and co had arity M and M < N, arityType would return ABot M which is wrong, because f is only known to diverge when applied to N args, as described in Note [ArityType]:

If at = ABot n, then (f x1..xn) definitely diverges. Partial
applications to fewer than n args may *or may not* diverge.

This caused incorrect eta expansion in the simplifier, causing #16066 (closed).

We now return ATop M for the same expression so the simplifier can't assume partial applications of f |> co is divergent.

A regression test T16066 is also added.

Fixes #16066 (closed).

Edited May 30, 2019 by Ömer Sinan Ağacan
Assignee
Assign to
8.8.1
Milestone
8.8.1 (Past due)
Assign milestone
Time tracking
Reference: ghc/ghc!1055
Source branch: fix_t16066