Highlights of the release

• Bundle scala-cli in scala command (For RC1 requires JVM 17, further RCs will use native launchers)
• Introduce Best Effort compilation options #17582
• Add support for Pipelined builds #18880
• Add support for var in refinements #19982
• Implement SIP-42 - Support for binary integer literals #19405

Other changes and fixes

Backend

• Fix Closure span assignment in makeClosure #15841

Default parameters

• Fix default args lookup for given classes #20256
• Fix implicit search failure reporting #20261

Derivation

• Fix infinite loop in Mirror synthesis of unreducible match type #20133

Desugaring

• Add explanation to checkCaseClassInheritanceInvariant error msg #20141

Exports

• Add annotations in parameters for exports #20140
• Fix isAliasType #20195

Implicits

• Fix implicitNotFound message for type aliases #19343
• Normalize types before collecting parts determining implicit scope #20077
• Better error diagnostics under -explain-cyclic #20251
• Update unreducible match types error reporting #19954
• Improve ConstraintHandling of SkolemTypes #20175

Incremental Compilation

• Retain default parameters with export #20167

Inline

• Fix by-name parameter in beta-reduction #20096
• Add warning for anonymous inline classes (#16723) #20291
• Avoid conversion of Unit type into () term #20295
• Type desugared transparent inline def unapply call in the correct mode #20108
• Regression: fix compilation performance on Windows #20193
• Fix inline match on blocks with multiple statements #20125
• Inline unapplys in the inlining phase #19382
• Fix outerSelect in Inliner #20313

Linting

• Fix #20146: attach the original name if there is an import selection for an indent #20163
• Add regression test for issue 18632 #20308

Match Types

• Make aliases of MatchAliases normal TypeAliases #19871
• Fix #19746: Do not follow param term refs in isConcrete. #20015
• Do match type reduction atPhaseNoLater than ElimOpaque #20017
• Do not flag match types as Deferred and amend #20077 #20147
• Always use baseType when constraining patternTp with scrutineeTp #20032
• Use MirrorSource.reduce result for companionPath #20207
• Regression: Fix match type extraction of a MatchAlias #20111

Polyfunctions

• Discard poly-functions when trying to resolve overloading #20181

Presentation Compiler

• Stabilise returned completions by improving deduplication + extra completions for constructors #19976
• Fix active param index for empty param lists #20142
• Delias type members in hover #20173
• Interactive: handle context bounds in extension construct workaround #20201
• Fix: prefer non-export definition locations #20252
• Don't show enum completions in new keyword context #20304
• Chore: Backport changes for presentation compiler #20345
• Add custom matchers for completions (fuzzy search for presentation compiler) #19850

Quotes

• Fix TermRef prefixes not having their type healed #20102
• Improve reporting in staging about the possible use of an incorrect class loader #20137
• Introduce MethodTypeKind to quotes reflection API #20249
• Add quote ASTs to TASTy #20165

Reflection

• Allow to beta reduce curried function applications in quotes reflect #18121
• Set the inlining phase in the Context used for checking macro trees #20087
• Add Symbol.isSuperAccessor to reflection API #13388
• Stabilize reflect SymbolMethods.isSuperAccessor #20198

Repl

• Fix validity period of derived SingleDenotations #19983
• Fix #18383: Never consider top-level imports as unused in the repl. #20310

Reporting

• Warn if extension receiver already has member #17543
• Deprecation of case class elements #17911
• Support src filter in -WConf (Closes #17635) #18783
• Add note about type mismatch in automatically inserted apply argument #20023
• Make error reporting resilient to exception thrown while reporting #20158
• Remove duplicate comma from Matchable selector warning #20159
• Generalize warnings for top-level calls to Any or AnyRef methods #20312
• Make CheckUnused not slow. #20321

Rewrites

• Patch indentation when removing braces (and other bug fixes in -indent -rewrite) #17522
• Extra check to avoid converting block expressions on the rhs of an in… #20043

Scaladoc

• Fix scaladoc crash on Windows - illegal path character #20311
• Scaladoc: improve refined function types rendering #20333
• Relax font-weight reset #20348

Scala JS

• Optimize main.js #20093

Settings

• Lift Scala Settings from experimental to stabilized #20199

Tooling

• Detect macro dependencies that are missing from the classloader #20139
• Write pipelined tasty in parallel. #20153
• ConsoleReporter sends INFO to stdout #20328

Transform

• Fix overloaded default methods test in RefChecks #20218
• Fix handling of AppliedType aliases in outerPrefix #20190
• Elide unit binding when beta-reducing #20085

Typer

• Reduce projections of type aliases with class type prefixes #19931
• Re-lub also hard union types in simplify #20027
• Fix #19789: Merge same TypeParamRef in orDominator #20090
• Allow SAM types to contain match alias refinements #20092
• Don't dealias when deciding which arguments to defer #20116
• Avoid the TypeVar.inst trap #20160
• Avoid crash when superType does not exist after erasure #20188
• Refine overloading and implicit disambiguation #20084
• Refactor constant folding of applications #20099
• Rollback constraints if isSameType failed second direction #20109
• Suppress "extension method will never be selected" for overrides #20164
• Allow SAM types to contain multiple refinements #20172
• Normalize when verifying if TypeTestCasts are unchecked #20258

Experimental Changes

• Named tuples second implementation #19174
• Change rules for given prioritization #19300
• Enable experimental mode when experimental feature is imported #19807
• Add message parameter to @experimental annotation #19935
• Implement match type amendment: extractors follow aliases and singletons #20161

Capture Checking

• Carry and check universal capability from parents correctly #20004
• Make parameter types of context functions inferred type trees #20155
• Handle reach capabilities correctly in depedent functions #20203
• Fix the visibility check in markFree #20221
• Make inline proxy vals have inferred types #20241
• CC: Give more info when context function parameters leak #20244
• Plug soundness hole for reach capabilities #20051
• Tighten the screws a bit more to seal the soundness hole for reach capabilities #20056
• Drop retains annotations in inferred type trees #20057
• Allow @retains arguments to be context functions #20232
• Fix conversion of this.fld capture refs under separate compilation #20238

Erased definitions

• Fix "Compiler crash when using CanThrow" #20210
• Only allow erased parameters in erased definitions #19686

Initialization

• Deprecate StandardPlugin.init in favor of initialize method taking implicit Context #20330
• Fix missing changesParents in PostTyper #20062
• Special case for next field of colon colon in global init checker #20281
• Extend whitelist in global initialization checker #20290

Macro Annotations

• Allow macro annotation to transform companion #19677
• Remove experimental MainAnnotation/newMain (replaced with MacroAnnotation) #19937

Nullability

• Add flexible types to deal with Java-defined signatures under -Yexplicit-nulls #18112
• Fix #20287: Add flexible types to Quotes library #20293
• Add fromNullable to Predef for explicit nulls #20222

Contributors

Thank you to all the contributors who made this release possible 🎉

According to git shortlog -sn --no-merges 3.4.2..3.5.0-RC1 these are:

   137	Martin Odersky
    51	Eugene Flesselle
    32	Jamie Thompson
    25	Nicolas Stucki
    22	Sébastien Doeraene
    18	noti0na1
    16	Matt Bovel
    12	Guillaume Martres
     9	Paweł Marks
     9	Yichen Xu
     8	Jan Chyb
     7	Hamza REMMAL
     6	Jędrzej Rochala
     6	Som Snytt
     5	Fengyun Liu
     5	dependabot[bot]
     3	Mikołaj Fornal
     2	Aviv Keller
     2	EnzeXing
     2	Wojciech Mazur
     1	Chris Pado
     1	Filip Zybała
     1	Georgi Krastev
     1	Hamza Remmal
     1	Jisoo Park
     1	Katarzyna Marek
     1	Lucas Nouguier
     1	Lucy Martin
     1	Ola Flisbäck
     1	Pascal Weisenburger
     1	Quentin Bernet
     1	Raphael Jolly
     1	Stephane Bersier
     1	Tomasz Godzik
     1	Yoonjae Jeon
     1	aherlihy
     1	rochala
     1	willerf