typelevel/spire

Use of bug in `cfor` macro

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#1,225 opened on Nov 25, 2022

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 (7 comments) (0 reactions) (0 assignees)Scala (1,775 stars) (238 forks)batch import
bughelp wanted

Description

The cfor macro accidentally generated the desired code by using a bug in beta-reduction. This bug will be patched https://github.com/lampepfl/dotty/pull/16390 and cfor will need to be updated.

See https://github.com/dotty-staging/spire/compare/7f630c0209e327bdc782ade2210d8e4b916fddcc...99ea909d086e28e85dbdf8aa78ef0a83bf873405#diff-9cd0f3a9df06a2589472aa8dc960fd2a65a2b65f2f8c257addda1c86ebc31469

Contributor guide

Tech stack
scala
Domain
tooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Scalamacros
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Check the linked dotty PR (https://github.com/lampepfl/dotty/pull/16390) for the beta reduction fix. Then update the `cfor` macro in Spire to use the proper behavior without relying on the bug. Examine the diff in the linked fork (https://github.com/dotty staging/spire/compare/...) for reference.