Highlights of the release

• Support for JDK 26 #24430
• Multiple coverage improvement to make it on par with Scala 2 support including
  // $COVERAGE-OFF$ and // $COVERAGE-ON$ markers
• New @uncheckedOverride annotation for definitions that may override
  #24545
• Trap Ctrl-C in the REPL: if no command is running clear the prompt, if some
  command is running ask for confirmation before exiting
  #24127
• Numerous linting and presentation compiler improvements and fixes

Other changes and fixes

Access modifiers

• Check protected parent constructor accesses only occurs in child constructors
  #25511
• Fix protected constructor access
  #25523

Annotations

• Improve ref check of constructors
  #24342
• Also copy param annots at mixin
  #24916
• Named arg may be deprecatedName
  #21588
• Fix: emit deprecation warnings when a symbol is annotated by a deprecated
  annotation #23906
• Fix #20063: Java leading annotation parsing
  #25503
• Accommodate adapted Scala 2 annotation value
  #17516
• Regression test for #3403 #25521
• Fix: do not allow @targetName on primary constructor too
  #24682
• Add @uncheckedOverride annotation for definitions that may override
  #24545

Backend

• Chore: add regression test for #4528
  #24663
• Cast inline call results to result type, not method type
  #25111
• Regression tests for #25 #25536
• Enforce JVM UTF-8 string limits in the backend
  #25300
• Do not simplify isInstanceOf if unrelated types might be subtypes at run-time
  #25535
• Adjust purity of trait with lazy member
  #23788
• Use Objects.equals in translating ==
  #25314
• Fix generic signatures for mixin forwarders conflicting type parameter names
  #24567
• No mixin forwarder when ancestor is sealed
  #23482
• Simplify JVM interface list emission, remove a mini-phase
  #25203
• Chore: optimize lazy val with power of two
  #22428

Classpath

• Skip module-info.class files during REPL tab-completion
  #24838
• Fix for #22461 Empty ClassPath attribute in one or more classpath jars causes
  crash #22462

Coverage

• Make coverage more similar to the one in Scala 2
  #23722
• Fix #25555: Preserve singleton precision during scoverage lifting
  #25556
• Fixes #25482: Ensure package transformation properly handles language imports
  in InstrumentCoverage #25546
• Bugfix: Fix issues with Scala JS and coverage
  #24769
• Make coverage support incremental compilation
  #24773
• Add support for local coverage on and off with // $COVERAGE-OFF$ and
  // $COVERAGE-ON$ #24486
• Improvement: Try to optimize coverage phase
  #24925
• Scoverage: do not instrument erased values
  #25298

Default parameters

• Fix named arguments evaluation order with by-name parameters
  #25161

Documentation

• Docs: Enforce links checks in the generated docs
  #25425
• Improve the contributing guide
  #25384
• Extend copyright into 2026
  #24927
• Update README: This is Scala 3
  #25424
• Explain implicit vs default args
  #25311
• Fix some scaladoc in compiler
  #24166
• Docs: fix task name for scaladoc/testOnly
  #23678
• Replace internal tab char in comment in Synthesizer.scala
  #23691

Enums

• Fix Java enum forwarders to pull from companion on initialization
  #24361
• Make enum apply ascriptions inferred types
  #25562

Exports

• Fix: look at the underlying of a TermRef for a getter
  #24565

Extension Methods

• Accept using right associative parameters
  #24766
• Add ctor proxies before exports
  #24884
• Fix pkg obj prefix of opaque tp ext meth
  #21527
• Better handling of illegal trees in extension
  #25368
• Fix LiftToAnchors for higher-kinded type applications
  #23672
• Prevent crash when extension not found
  #18830

GADTs

• Also trust TypeTest when there is a Bind
  #24568

Implicits

• Only check seen for LazyRef for TypeSizeAccumulator
  #20459
• Chore: add regression test for #8581
  #24666
• Fix "Regression in zio/zio-schema for typer/implicit resolution"
  #24156
• Fix implicit scope liftToAnchors for parameter lower bounds
  #23679

Inference

• Tweak type for tryParameterless
  #24716

Initialization

• Refine parameter adaptation logic for arrays
  #23591

Infrastructure

• Tweak tests to not fail under jdk 25
  #25148
• Bump actions/upload-artifact from 6 to 7
  #25423
• Bump actions/download-artifact from 7 to 8
  #25420
• Bump VirtusLab/scala-cli-setup from 1.12.2 to 1.12.3
  #25422
• Bump coursier/cache-action from 7 to 8
  #25220
• Bump actions/upload-artifact from 5 to 6
  #24758
• Bump actions/download-artifact from 6 to 7
  #24759
• Bump actions/checkout from 5 to 6
  #24517
• Bump actions/upload-artifact from 4 to 5
  #24268
• Bump actions/download-artifact from 5 to 6
  #24271
• Bump actions/download-artifact from 4 to 5
  #23711
• Bump actions/checkout from 4 to 5
  #23710
• Chore: bump sbt to 1.11.5 #23805
• Chore(deps): bump actions/setup-java from 4 to 5
  #23812
• Chore: Use numberOfWorkers instead
  #24338
• Improvement: Additional way of defining ENABLE_BSP_ALL_PROJECTS
  #24122
• Formatting: Format presentation-compiler with scalafmt
  #24977

Inline

• Chore: add regression test for #22575
  #25337
• Ensure the inline match scrutinee type conforms to the recalculated type
  #24988
• Make containsOuterRefsAnywhere follow aliases
  #25214
• Find annotation args in inline expansion
  #24895
• Chore: add regression test for #10343
  #24668
• Improve the test for creating protected method accessors for inlines
  #25865
• Do not update Symbol defTrees when retyping after Inlining
  #23870
• Prevent opaque types leaking from transparent inline methods
  #23792
• Chore: add regression test for #8194
  #24655
• Also substitute symbols in case bindings symbols
  #24849
• Inlines: decide sealing against original target, while using widened type as
  cast destination #25448
• Fix inline match on blocks with multiple statements
  #20125

JDK

• Skip over JEP 445 compact compilation units
  #23247
• Handle MissingType during Erasure phase
  #24817
• Don't generate bridge methods for inaccessible Java package-private methods
  #25166
• Fix isJvmAccessible to handle nested protected Java classes
  #24625
• Upgrade ASM to 9.9 for JDK 26 support
  #24430
• Fix java record varargs field accessor
  #24172

Linting

• Fix false unused import warning for given CanEqual in pattern matching
  #25231
• Move second CheckUnused after pattern matcher
  #25114
• Extension check handles hiBound of opaque type
  #25172
• Unused lint ignores args to ctor of enclosing class
  #24768
• Parameter name can be masked in import
  #24635
• CheckUnused examines type of Apply
  #24465
• Check for synthetic case methods in unused lint
  #24239
• Lint avoids revisiting Inlined.call
  #24277
• Register no elements for lint after inlining
  #24279
• Ignore warnings when compiletime.testing is imported
  #24036
• Unused lint does not rewrite suppressed warnings
  #24055
• Drill through type lambda for tree symbol
  #23699
• Invent given pattern name in for comprehension
  #23121
• Check inline expansion for exclusion
  #23019
• Unused var message mentions unread or unset
  #23719
• Warn unused masking imports, remove obsolete unused options
  #23757
• Distrust tree pos for patvar lint
  #25043
• Match apply in PolyFunction for override
  #25505
• Value discard checks inline call for exemption
  #25554
• Lint enum case in outer context
  #24652
• Preserve select of exported member in newExpr
  #24570
• Always traverse Inlined.call in linter
  #24043
• Lint function arrow intended context function
  #23847
• Use enclosing enclosingInlineds for empty call
  #24281
• Exclude synthetic opaque proxy from lint
  #24264
• Regression test locals #25433
• Augment regression test #24327

Match Types

• Fix regression: Prioritize tree type over proto type when typing Binds
  #24175

Metaprogramming

• Warn about encoded pkg obj names
  #22707
• Bugfix: Fix possible SuspendException thrown when using macros
  #24174

Nullability

• Patch to allow interop with XMLBuilder and -Yexplicit-nulls
  #25221
• Add jspecify NonNull annotation to NotNullAnnots list
  #24487
• Add quick fix to add .nn #23598

Opaque Types

• Preserve insertion order when balancing And/OrType
  #25361
• Treat synthetic casts as pure
  #25126
• Make opaque types decomposable
  #24068

Overloading

• Pretype args before skipping clause of overloaded application
  #23012
• Fix varargs overload resolution with wildcard types
  #24669
• Fix wildcardArgOK for mixed wildcard/concrete type args
  #25001
• Regression test #16004 #24086
• Tweak tryParameterless to use readapt
  #24078
• Fix override checking for Java methods with covariant array
  #24408
• Prefer non-extension to extension
  #24943
• Fix class super-call invokespecial owner
  #25437

Parser

• Accept primitive.class in annotations
  #25363
• End of new expr never shrinks
  #25253
• Permit new with trivial end
  #24331
• Improve message for nested package missing braces
  #23816
• Check seen for TypeParamRef in TypeSizeAccumulator
  #25264
• Observe outdent also for type cases and type blocks in quotes
  #25519
• Fix: import resolution for Java
  #25537
• Error tree on outdent is zero extent
  #23796
• Don't automatically insert OUTDENT before COMMA
  #25501
• Fix: allow postfix setters under language.postfixOps
  #23775
• Additional regression tests
  #25506

Pattern Matching

• Emit unchecked warnings for trait patterns
  #24962
• Fix false exhaustivity warning for seq match
  #23968
• Call inhabited for AppliedType recursively
  #23964
• Fix Ycheck crash from singleton tuple selects after specialization
  #25331
• Fix false unreachable case warning
  #23800
• Use upper bound of abstract types in exhaustivity checking
  #23909
• Extend caching in the space engine beyond local context
  #23483
• Prevent from getting children in case of non-sealed private
  #25359
• Use MatchCaseUnreachable #24829
• Preserve singleton types for final val aliases to Java enum constants
  #24980
• Try expanding case class to the product of its fields
  #25454
• Never widen constant type on selector type in matches
  #25197

Pickling

• Fix #24456: Cleanup the info of a Bind symbol in posttyper
  #24490
• Fix #24207: Cleanup the type of UnApply trees in posttyper
  #24259
• Chore: add a regression test for #15786
  #24658
• Don't absolutize sources outside of the sourceroot in TASTy
  #25429

Positions

• Preserve span of this during statification of trait constructors
  #25354
• Compute the right span for abstract error messages
  #23853
• Use a better span for an anonymous class
  #24640

Presentation Compiler

• Improvement: Use method type if it's available
  #25641
• Bugfix: Don't add square braces in context bounds
  #25798
• Bugfix: Fix issue with empty name throwing exceptions
  #25752
• Bugfix: Fix wrong type in InferredType code action
  #25469
• Bugfix: Fix issues in presentation compiler when using Scala JS
  #25450
• Improvement: Add fallbacks in non critical places for presentation compiler
  #25483
• Fix & feat: improvements in selection ranges
  #25290
• Feat(pc): add closing labels inlay hints
  #25178
• Bugfix: remove stale top-level symbols between runs
  #25317
• Bugfix: Fix various minor presentation compiler issues
  #25256
• Fix: ignore implicit apply for signature help
  #25294
• Fix incorrect XRay hint #24738
• Presentation compiler: propagate isDebug timeout check to all tests
  #25068
• Handle inlined tree in implicit parameter inlay hints
  #24762
• Create extension method in infer method action
  #24721
• Fix opaque types displayed as Nothing & Any in hover and signature help
  #24921
• Fix negative activeParameter in signature help
  #24945
• Closes #7532: Parameter hints not working for functions
  #23854
• Improvement: Allow passing -explain to the presentation compiler
  #24740
• Exclude XRayModeHint for synthetics
  #24722
• Add unsafe RawPresentationCompiler implementation
  #24133
• Bugfix: Make sure that we can query tree.source
  #24123
• Improvement: additional completions for using clause
  #23647
• Inlining interpolated variables
  #25144
• Bugfix: inline value false-positive shadowing with lambda params
  #25140
• Fix issue with pc breaking in requiredMethod on newly overloaded valueOf
  #23708
• Pc: completions - do not add [] for ... derives TC@@
  #23811
• Porting XRayModeHints #23891
• Improve symbol order in completions provided by the presentation compiler
  #23888
• Bugfix: Fix issues with Scala JS and the presentation compiler
  #25550
• Bugfix: Show hover on derives clause
  #25804
• Improvement: improve perfomance of the presentation compiler
  #25769
• Coursier dependency imports should have lexicographic ordering
  #21592

Quotes

• Fix crashing for context bound type variables in quoted patterns
  #25286
• Fix #25208: handle AndType(TermRef, TypeRef) in TreeUnpickler path trees
  #25209
• Remove redundant mapOver in fixThisTypeModuleClassReferences
  #25440
• Make typeArgs in QuotesImpl work for AnnotatedTypes
  #24018
• Improve LambdaTypes handling in Quotes reflect memberType
  #25786

Reflection

• Fix Select.copy in reflect API losing DerivedName for default getters
  #25269
• Do not expose ClassInfo in memberType in reflect API
  #24922
• Quotes reflect: Allow to return DefDef from a val symbol tree
  #22603

Reporting

• Force conditional warnings when configured
  #25552
• Use deprecatedOverriding message
  #25439
• Fix #24711: Use dot notation for Java nested types in error messages
  #24919
• Enhance WInferUnion to not warn propagated explicit union types
  #25280
• Fixes #24233: Remove misleading JDK compatibility hint for TASTy errors
  #25171
• More descriptive "not found" message when type/term exists with the expected
  term/type name #24959
• Mention named givens in double def explainer
  #23833
• Do not discard amended format when f-interpolator warns
  #23697
• Use dollar-free param names in stub implementations
  #25646
• Error mentions bad _1 selector
  #25616
• Add ErrorMessageID to -Winfer-union warnings (#25073)
  #25249
• Addendum when apply error involves default arg
  #21133
• Warn on Scala 2 auto-apply if loosely nullary
  #24811
• Forward reference error includes line numbers
  #22534
• Use other tree for actual symbol of Assign
  #22869
• Add "did you mean to use parentheses/a block" when finding a complex
  expression on the RHS of an infix operator
  #25099
• Fix printing references to nested objects
  #25086
• Add error note for type mismatch involving blocks without last expression
  #25181
• Don't suggest invisible members of root imports
  #24999
• Improve multi-line code message rendering
  #24723
• Warn if type argument was inferred as union type
  #24258
• Improve printing of strings
  #22945
• Better error message: reassignment to val
  #24184
• Add addendum to private val parameter variance error message
  #23876
• Regression tests #24876

REPL

• Make REPL type echo-ing use partially qualified names where made possible by
  imports #24850
• Remove pipes from multi-line REPL prompts
  #24307
• Fix "Colon as operator part at beginning of line in REPL"
  #24942
• Trap Ctrl-C in the REPL: if no command is running clear the prompt, if some
  command is running ask for confirmation before exiting
  #24127

Rewrites

• Deduplicate patches before applying them to sources
  #24215

Runner

• Fix for #22443: prevent stty from being called when not running in a terminal
  #22444

Scaladoc

• Do not hide when a class or a trait extends Any
  #25403
• Ability to hide snippets from the documentation
  #25411
• Use <sup> tags for exponents in Scaladoc comments
  #25645
• Fix duplicate member entries in Scaladoc generation
  #24712
• Scaladoc Overload Method Link Fix
  #25156
• Init MacroClassLoader in scaladoc
  #25141
• Scaladoc: Take title from sidebar.yml into account
  #18997
• [scaladoc] Allow to additional scalacOptions in Markdown code snippets
  #24755
• Fetch the right kind for synthesised definitions
  #25405
• Add the transparent flag to java.lang.Object
  #25394

SemanticDB

• Add context parameters to SemanticDB synthetics
  #23381
• Better refinement symbols in semanticDB
  #18604
• Encapsulate SemanticDB package, unify symbol and document printing
  #25084

Testing

• Fix line and path separators in test
  #23534
• Fix: update checkfile for i23905
  #24064

Testing framework

• Reject check file match with stack trace
  #22389
• Cleanup compiler test. remove unnecessary isJavaAtLeast conditions
  #24589
• Bugfix: Don't run coverage tests in testCompilation without --coverage flag
  #24932
• Cleaner, quieter test rig tests
  #24073
• Skip tests with no sources such as .scala-build dir
  #25173
• Report info logs in checked test output if enabled with -Ylog
  #25391
• Bugfix: Fix flaky test in ScalaJSCompletionsSuite
  #25539
• Add regression test for #23195
  #24853
• Test hover on backticked identifiers with whitespace
  #25142

Transform

• Check extension method at typer
  #24199
• Always encode in derived name
  #23478
• Fix "Scala 3.8.3 compiling covariant overrides with separate compilation
  causes AbstractMethodError at runtime"
  #25659
• Make Phase.run protected #25366

Tuples

• Fix inconsistent typeSize calculation for TupleN vs recursive pair
  encodings #24743
• Fix: make vals created in desugaring of n-ary lambdas non-synthetic
  #23896
• Normalize tuple types when typing patterns
  #25335
• Fix #24997: Avoid unnecessary CHECKCAST in untupled function parameters
  #25085

Typeclass Derivation

• Fix #23043: spurious package conflict from non-class directories
  #25441
• Also checkRefinement for Singleton mirror
  #24080

Typer

• Use TypeComparer.constValue in TypeEval
  #24718
• Fix crash in Selectable unapply with custom applyDynamic
  #24343
• Prevent crash in SAM conversion with mismatched arity
  #23877
• Detect InsertedApply on Apply to break synthetic apply loops, not just
  Select #25463
• Typer: remove by-name lifting and replace default-getter args with fresh syms
  #25502
• Refine isEffectivelyFinal to avoid no-owner crash
  #23675
• Do not generate access proxies for locally defined protected defs
  #25056
• Use dealiasKeepRefiningAnnots in AvoidMap
  #25609
• Fix #24573: Add stricter checks for platform SAM compatibility
  #24624
• Make isExactlyNothing and isExactlyAny work for And/OrTypes
  #24016
• Handle assertion error in TyperState
  #23665
• Fix: correctly require a ClassTag when building a multidimensional Array
  #23902
• Fix crash when processing path dependent context functions using HKTs
  #25530
• Regression test #24820
• Chore: add regression test for #13889
  #24657

XML

• Use toVector for XML literal sequences
  #23221

Union types

• Dealias in isSimpleThrowable check
  #24744