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[2.x] fix: Fix pipelining flags applied to unsupported Scala versions#8499

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eed3si9n merged 3 commits intosbt:developfrom
0xsatoshi99:fix-pipelining-version-check
Jan 13, 2026
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[2.x] fix: Fix pipelining flags applied to unsupported Scala versions#8499
eed3si9n merged 3 commits intosbt:developfrom
0xsatoshi99:fix-pipelining-version-check

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@0xsatoshi99 0xsatoshi99 commented Jan 12, 2026

Problem

When usePipelining := true is set with Scala 3.3.x or 3.4.x, sbt applies -Ypickle-java and -Ypickle-write compiler flags even though pipelining is only supported in Scala 3.5.0+. This causes confusing warnings:

[warn] bad option '-Ypickle-java' was ignored
[warn] bad option '-Ypickle-write' was ignored

Solution

Added version check to only apply pipelining compiler flags when Scala 3.5.0 or later is detected. The check uses existing utilities (ScalaArtifacts.isScala3 and VersionNumber.matchesSemVer) following the pattern already used elsewhere in the codebase.

Changes

  • Modified scalacOptions setting in Defaults.scala to check Scala version before applying pipelining flags
  • Flags are now only added for Scala 3.5.0+
  • For earlier versions, usePipelining setting is silently ignored

Fixes #8433

Contribution by Gittensor, see my contribution statistics at https://gittensor.io/miners/details?githubId=162055292

@0xsatoshi99
Fix pipelining flags applied to unsupported Scala versions
75a7e2d 
Pipelining was introduced in Scala 3.5.0 but the build was applying
-Ypickle-java and -Ypickle-write flags to all Scala 3 versions when
usePipelining was enabled, causing warnings on Scala 3.3.x and 3.4.x.

This change adds version detection to only apply pipelining compiler
flags when Scala 3.5.0 or later is used.

Fixes sbt#8433

Generated-by: AI-assisted
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0xsatoshi99 commented Jan 12, 2026

@eed3si9n Can you please check this PR and give me feedback if you have any? Thanks.

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eed3si9n requested changes Jan 12, 2026
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eed3si9n commented Jan 12, 2026

Thanks for the contribution, I left a comment.

@0xsatoshi99
Fix pipelining check to allow Scala 2.x
c9743e5 
As pointed out by @eed3si9n, Scala 2.x has supported pipelining since 2020.
The fix now correctly allows:
- All Scala 2.x versions (pipelining supported)
- Scala 3.5.0+ (pipelining added in 3.5)

And only blocks Scala 3.0-3.4.x which lack pipelining support.
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0xsatoshi99 commented Jan 13, 2026

Thank you @eed3si9n for the correction! You are absolutely right - I misunderstood the issue. Scala 2.x has supported pipelining since 2020.

I have updated the logic to:

  • Allow all Scala 2.x versions (pipelining supported)
  • Allow Scala 3.5.0+ (pipelining added in 3.5)
  • Block only Scala 3.0-3.4.x (no pipelining support)

The fix now uses !ScalaArtifacts.isScala3(sv) || VersionNumber(sv).matchesSemVer(SemanticSelector(">=3.5.0")) which correctly handles all cases.

@0xsatoshi99 0xsatoshi99 requested a review from eed3si9n January 13, 2026 00:23
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Thanks!

@eed3si9n eed3si9n changed the title Fix pipelining flags applied to unsupported Scala versions [2.x] fix: Fix pipelining flags applied to unsupported Scala versions Jan 13, 2026
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0xsatoshi99 commented Jan 13, 2026

Applied scalafmt formatting to fix CI/CD check. The code logic remains the same, just properly formatted according to the project style guide.

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0xsatoshi99 commented Jan 13, 2026

@eed3si9n Can you please merge this PR?

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anatoliykmetyuk commented Jan 13, 2026

CI didn't run for some reason, we need to approve workflows and run the CI.

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eed3si9n commented Jan 13, 2026

CI didn't run for some reason, we need to approve workflows and run the CI.

First time contributors require approve-and-run each time they change the pull request.

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0xsatoshi99 commented Jan 13, 2026

Screenshot_18 Screenshot_19 Screenshot_20

When I try to sign Scala, I am getting 500 error, how I can fix this? @eed3si9n

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0xsatoshi99 commented Jan 13, 2026

The CI scripted tests are failing with errors in dependency-management/cache-resolver and other tests, but these appear unrelated to this PR:

  • The failures are in dependency resolution, caching, and project matrix tests
  • This PR only modifies scalacOptions logic in Defaults.scala
  • The error (sjsonnew.shaded.org.typelevel.jawn.IncompleteParseException) is a JSON parsing issue in the caching system
  • scalafmtCheckAll and compilation passed successfully

The code change is minimal and scoped to pipelining flag application. Could these be pre-existing test issues or flaky tests?

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eed3si9n commented Jan 13, 2026

Looks like CLA worked after rerunning. I'm rerunning the failing tests.

@eed3si9n eed3si9n merged commit 3a9e1ec into sbt:develop Jan 13, 2026
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usePipelining generates bad options when unsupported

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