scala

The Scala team at Lightbend is pleased to announce Scala 2.13.15. The following changes are highlights of this release: ### Breaking changes * `-Wconf:x,y` now means `-Wconf:x -Wconf:y`, with y overruling x, rather than the reverse (to align with Scala 3.4+ and with user intuition) ([#10708](https://github.com/scala/scala/pull/10708) by [@som-snytt](https://github.com/som-snytt)) * Compiler plugins: rework and improve phase assembly ([#10687](https://github.com/scala/scala/pull/10687) by [@som-snytt](https://github.com/som-snytt)) * Plugin authors should check to see if they are affected * Plugin users may see strange errors if a plugin is affected and not adjusted by its author * Most plugins are not affected ### Compatibility * Support JDK 23 in optimizer (via upgrade to patched ASM 9.7.0) ([#10744](https://github.com/scala/scala/pull/10744)) * Support Scala 3.5 in TASTy reader ([#10811](https://github.com/scala/scala/pull/10811) by [@bishabosha](https://github.com/bishabosha)) * REPL: JLine 3.26.3 (was 3.25.1) ([#10827](https://github.com/scala/scala/pull/10827)) ### Features * Support alternative JVM system images (via `-system`, like javac) ([#10801](https://github.com/scala/scala/pull/10801) by [@szeiger](https://github.com/szeiger)) * Add `-Ycollect-statistics` for collecting statistics without printing them ([#10795](https://github.com/scala/scala/pull/10795) by [@szeiger](https://github.com/szeiger)) ### Align with Scala 3 * Add `-Xsource-features:double-definitions` to warn or error for double definitions ([#10846](https://github.com/scala/scala/pull/10846) by [@som-snytt](https://github.com/som-snytt)) * Under `-Xsource:3`, allow importing `given`, for cross-building ([#10786](https://github.com/scala/scala/pull/10786) by [@som-snytt](https://github.com/som-snytt)) * Under `-Xsource:3`, remove by-name restriction for case copy ([#10770](https://github.com/scala/scala/pull/10770) by [@som-snytt](https://github.com/som-snytt)) ### Errors and warnings * Fix `-Wconf` and `-nowarn` to be more consistent ([#10750](https://github.com/scala/scala/pull/10750) by [@som-snytt](https://github.com/som-snytt)) * Add `-Wtostring-interpolated` to warn if interpolator uses `toString` ([#10776](https://github.com/scala/scala/pull/10776) by [@som-snytt](https://github.com/som-snytt)) * Improve inferred-`Any` lint (fixing false positives and false negatives) ([#9452](https://github.com/scala/scala/pull/9452) by [@som-snytt](https://github.com/som-snytt)) * Fix false-positive unused warnings in for comprehensions ([#10812](https://github.com/scala/scala/pull/10812) by [@som-snytt](https://github.com/som-snytt)) * (Still seeing false positives, or new false positives? see https://github.com/scala/scala/pull/10870) * Fix false-positive by-name implicit warnings with `-Wmacros` ([#10781](https://github.com/scala/scala/pull/10781) by [@som-snytt](https://github.com/som-snytt)) * Mention if missing symbol is on the class path ([#10774](https://github.com/scala/scala/pull/10774) by [@som-snytt](https://github.com/som-snytt)) * Avoid unused import warnings in REPL ([#10769](https://github.com/scala/scala/pull/10769) by [@som-snytt](https://github.com/som-snytt)) * Add `-Vcyclic` to improve reporting of "cyclic reference" errors ([#10680](https://github.com/scala/scala/pull/10680) by [@som-snytt](https://github.com/som-snytt)) ### More changes For the complete 2.13.15 change lists, see [all merged PRs](https://github.com/scala/scala/pulls?q=is%3Amerged%20milestone%3A2.13.15) and [all closed bugs](https://github.com/scala/bug/issues?utf8=%E2%9C%93&q=is%3Aclosed+milestone%3A2.13.15). ## Compatibility As usual for our minor releases, Scala 2.13.15 is [binary-compatible](https://docs.scala-lang.org/overviews/core/binary-compatibility-of-scala-releases.html) with the whole Scala 2.13 series. Upgrading from 2.12? Enable `-Xmigration` while upgrading to request migration advice from the compiler. ## Contributors A big thank you to everyone who's helped improve Scala by reporting bugs, improving our documentation, spreading kindness in discussions around Scala, and submitting and reviewing pull requests! You are all magnificent. We especially acknowledge and thank A. P. Marki, also known as Som Snytt, who is responsible for many of the improvements in this release. This release was brought to you by 13 contributors, according to `git shortlog -sn --no-merges @ ^v2.13.14 ^2.12.x`. Thank you A. P. Marki, Lukas Rytz, Scala Steward, Seth Tisue, Jamie Thompson, Stefan Zeiger, Hamza Remmal, EnzeXing, Marissa, Philippus Baalman, Samuel Chassot, luozexuan, nbauma109. Thanks to [Lightbend](https://www.lightbend.com/scala) for their continued sponsorship of the Scala 2 team’s efforts. Lightbend offers [commercial support](https://www.lightbend.com/lightbend-platform-subscription) for Scala. ## Scala 2.13 notes The [release notes for Scala 2.13.0](https://github.com/scala/scala/releases/v2.13.0) have important information applicable to the whole 2.13 series. ## Obtaining Scala Scala releases are available through a variety of channels, including (but not limited to): * Bump the `using scala` setting in your Scala-CLI project * Bump the `scalaVersion` setting in your sbt or Mill project * Download a distribution from [scala-lang.org](https://scala-lang.org/download/2.13.15.html) * Obtain JARs via [Maven Central](https://search.maven.org/search?q=g:org.scala-lang%20AND%20v:2.13.15)

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