scala/scala3

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The Scala 3 compiler, also known as Dotty.

Stars: 6.3k
Forks: 1.2k
Open beginner issues: 1
Indexed issues: 1.7k
Avg merge: 1d 17h
Merged PRs (30d): 126

Dominant language: Scala
License: Apache-2.0
Last GitHub push: Sep 18, 2026
Latest indexed: Sep 19, 2026
Contributing guide: Contributing guide
Code of conduct: No code of conduct
Beginner labels: help wanted good first issue

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1,702 open issues indexed

Generic signature of TupleXXL is java.lang.Object instead of scala.runtime.TupleXXL Open

itype:bug stat:needs triage

Difficulty 3/5 1-2 days Newbie friendliness 55/100

scala/scala3#27111 · Opened Sep 19, 2026
JEP 390: Warnings for Value-Based Classes Open

itype:bug stat:needs triage

Difficulty 3/5 1-2 days Newbie friendliness 70/100

scala/scala3#27110 · Opened Sep 19, 2026
`Cyclic reference involving` error in REPL Open

itype:bug stat:needs triage

Difficulty 4/5 3-5 days Newbie friendliness 50/100

scala/scala3#27108 · 1 comment · Opened Sep 19, 2026
no attempt was made to look for sufficiently-typed implicits where manually-passed instance works without complaint of mismatch Open

area:implicits itype:bug stat:needs minimization

Difficulty 5/5 Over a week Newbie friendliness 35/100

scala/scala3#27101 · Opened Sep 18, 2026
Presentation compiler crashes on inlay hints when a tree has a position in a TASTy-only/unreadable source Open

area:presentation-compiler itype:bug

scala/scala3#27098 · 6 comments · 1 assignee · Opened Sep 17, 2026
AssertionError: Failure to join alternatives — implicit search over an abstract type-constructor union crashes orDominator Open

area:typer itype:bug itype:crash

Difficulty 4/5 3-5 days Newbie friendliness 72/100

scala/scala3#27096 · Opened Sep 17, 2026
Still possible to swallow a Break with capture-checked Try Open

area:experimental:cc itype:bug

Difficulty 3/5 1-2 days Newbie friendliness 55/100

scala/scala3#27091 · Opened Sep 17, 2026
Break can leak out of boundary through mutable reference to Try Open

area:experimental:cc itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 35/100

scala/scala3#27090 · Opened Sep 17, 2026
False match type cyclic reference error Open

area:match-types itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 48/100

scala/scala3#27080 · Opened Sep 16, 2026
Inlined Java annotation with default value crashes backend Open

area:annotations compat:java itype:bug itype:crash

Difficulty 4/5 3-5 days Newbie friendliness 52/100

scala/scala3#27078 · 1 comment · Opened Sep 15, 2026
Reject misplaced standard annotations early in typer Open

area:annotations area:ux better-errors itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 48/100

scala/scala3#27065 · 1 comment · Opened Sep 12, 2026
Nondeterminism in specialized bound error message Open

area:specialized-traits itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 42/100

scala/scala3#27056 · Opened Sep 11, 2026
Odd compile error for `indexOf` with named arg Open

area:typer compat:java itype:bug

scala/scala3#27054 · 4 comments · 1 assignee · Opened Sep 11, 2026
Regression in optics-dev/monocle: macro expansion types no longer conform Open

area:metaprogramming:quotes itype:bug regression

Difficulty 4/5 3-5 days Newbie friendliness 48/100

scala/scala3#27032 · 5 comments · Opened Sep 9, 2026
TreePickler.scala:328 exception scala.MatchError: JavaArrayType(TypeRef(ThisType(TypeRef(NoPrefix,module class lang)),class String)) (of class dotty.tools.dotc.core.Types$CachedJavaArrayType) Open

area:pickling itype:bug itype:crash stat:fixed in next

scala/scala3#27009 · 5 comments · 1 assignee · Opened Sep 8, 2026
Resurrect `stackoverflowmacro` test and figure out why it's flaky Open

area:ci area:inline itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 45/100

scala/scala3#27002 · Opened Sep 8, 2026
ScalaJS TypeError when calling toString under explicit nulls and unsafeNulls Open

area:nullability area:scala.js itype:bug

scala/scala3#26999 · 2 comments · 1 assignee · Opened Sep 7, 2026
-Ycc-log crash Open

area:experimental:cc itype:bug itype:crash

Difficulty 3/5 1-2 days Newbie friendliness 68/100

scala/scala3#26986 · Opened Sep 4, 2026
Make SIP-72 Dedented Multiline String Literals a preview feature Open

itype:enhancement stat:needs preview

Difficulty 2/5 1-3 hours Newbie friendliness 65/100

scala/scala3#26981 · 3 comments · Opened Sep 4, 2026
Unsound `F[E] & S` unification inferring `F[Nothing]` Open

area:infer itype:bug regression

Difficulty 4/5 3-5 days Newbie friendliness 48/100

scala/scala3#26969 · 2 comments · Opened Sep 2, 2026
3.10 regression - false warning: the type test cannot be checked at runtime Open

area:inline area:metaprogramming:quotes itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 55/100

scala/scala3#26964 · 5 comments · 1 reaction · Opened Sep 2, 2026
misleading message `parameter was not considered wasn't imported with 'import given'` Open

area:implicits itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 35/100

scala/scala3#26952 · Opened Aug 31, 2026
Compiler assertion in RefChecks for symbolic extension over a recursive higher-kinded match type Open

area:extension-methods area:match-types itype:bug itype:crash

Difficulty 4/5 3-5 days Newbie friendliness 48/100

scala/scala3#26950 · Opened Aug 30, 2026
Compiler crashes on self invocation with too many argument lists on class that defines apply Open

area:backend itype:bug itype:crash

Difficulty 3/5 1-2 days Newbie friendliness 66/100

scala/scala3#26938 · Opened Aug 27, 2026
3.10: TASTy contains an enclosing PackageDef for the empty package, which should not be there Open

area:specialized-traits itype:bug

scala/scala3#26936 · 8 comments · 1 assignee · Opened Aug 27, 2026
Some stdlib doc comments use WikiDoc instead of Markdown Open

area:documentation itype:bug

scala/scala3#26923 · 1 assignee · Opened Aug 26, 2026
Using return type capture set for `this` breaks when intermediate value is present Open

area:experimental:cc itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 58/100

scala/scala3#26917 · Opened Aug 25, 2026
Capability leak possible via anonymous trait implementation Open

area:experimental:cc itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 38/100

scala/scala3#26884 · Opened Aug 21, 2026
assertion error for a higher-kinded extension method with a default argument in the presence of an extension-level using clause Open

area:erasure area:extension-methods area:implicits area:transform itype:bug itype:crash

Difficulty 4/5 3-5 days Newbie friendliness 48/100

scala/scala3#26862 · 1 comment · Opened Aug 19, 2026
`experimental.modularity` not working on `given`s Open

area:experimental:modularity area:implicits itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 42/100

scala/scala3#26856 · Opened Aug 19, 2026
Scaladoc fails to generate recursive self-type member docs Open

area:doctool itype:bug

scala/scala3#26852 · 1 assignee · Opened Aug 18, 2026
`Predef.->` as extension is always chosen over user-defined implicit class member Open

area:extension-methods area:implicits itype:bug stat:needs decision

Difficulty 4/5 3-5 days Newbie friendliness 48/100

scala/scala3#26851 · 8 comments · Opened Aug 18, 2026
Bounded opaque type no longer provides typeclass instance of the bound type Open

area:opaque-types itype:bug regression

Difficulty 4/5 3-5 days Newbie friendliness 38/100

scala/scala3#26849 · 2 comments · Opened Aug 18, 2026
Tuple specializations for Scala 3 (any arity) Open

area:tuples itype:enhancement

Difficulty 5/5 Over a week Newbie friendliness 35/100

scala/scala3#26841 · 2 comments · 1 reaction · Opened Aug 18, 2026
@specializedBy annotation Open

area:annotations area:specialized-traits itype:enhancement

Difficulty 5/5 Over a week Newbie friendliness 30/100

scala/scala3#26840 · 1 comment · Opened Aug 18, 2026
Adapt overloading to specialized traits Open

area:overloading area:specialized-traits itype:enhancement

Difficulty 5/5 Over a week Newbie friendliness 35/100

scala/scala3#26839 · Opened Aug 18, 2026
Support nested type definitions in inline traits Open

area:inline itype:enhancement needs-sip

Difficulty 5/5 Over a week Newbie friendliness 30/100

scala/scala3#26838 · 2 comments · Opened Aug 18, 2026
False positive unused CanEqual import Open

area:linting itype:bug

scala/scala3#26836 · 2 comments · 1 assignee · Opened Aug 17, 2026
Group DesugarSpecializedTraits and SpecializeInlineTraits into MegaPhase Open

area:specialized-traits itype:enhancement

Difficulty 4/5 3-5 days Newbie friendliness 48/100

scala/scala3#26821 · Opened Aug 17, 2026
Refactor Inlines.scala to separate inlining of defs and inlining of traits Open

area:specialized-traits itype:enhancement

Difficulty 4/5 3-5 days Newbie friendliness 52/100

scala/scala3#26820 · Opened Aug 17, 2026
`Tuple` `toList` method and friends with unusable signatures (MT application to singleton types) Open

area:tuples itype:bug regression

Difficulty 5/5 Over a week Newbie friendliness 35/100

scala/scala3#26817 · 2 comments · 1 reaction · Opened Aug 16, 2026
Type mismatch in Tuple.head with capture checking Open

area:experimental:cc area:tuples itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 48/100

scala/scala3#26815 · Opened Aug 16, 2026
Unable to reference capability in quotes Open

area:experimental:cc area:metaprogramming:quotes itype:bug

scala/scala3#26806 · 1 assignee · Opened Aug 14, 2026
Error on `@throws` to non-methods (align with Scala 2) Open

area:annotations area:ux better-errors itype:bug

Difficulty 3/5 1-2 days Newbie friendliness 65/100

scala/scala3#26804 · 1 comment · Opened Aug 14, 2026
Regression in lichess/lila during access to contextual member in Tuple arrow Open

area:tuples itype:bug regression

scala/scala3#26801 · 2 comments · 1 assignee · Opened Aug 13, 2026
Extension method not choosing available alternative in infix syntax Open

area:extension-methods itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 48/100

scala/scala3#26793 · 1 comment · Opened Aug 13, 2026
Better Errors - `misaligned end marker` Due To Missing `:` Open

area:reporting area:ux better-errors itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 52/100

scala/scala3#26789 · 1 comment · Opened Aug 13, 2026
Singleton type leaks from transparent inline method with double opaque types Open

area:inline area:opaque-types itype:bug itype:crash regression

scala/scala3#26785 · 5 comments · 1 assignee · Opened Aug 12, 2026
Scoverage: lifted stable argument gets a new capture identity in Iterator.iterate Open

area:coverage area:experimental:cc itype:bug

Difficulty 4/5 3-5 days Newbie friendliness 48/100

scala/scala3#26784 · Opened Aug 12, 2026
AssertionError with captureChecking, separate compilation, and byname param Open

area:experimental:cc itype:bug itype:crash

Difficulty 4/5 3-5 days Newbie friendliness 55/100

scala/scala3#26783 · Opened Aug 12, 2026

scala/scala3

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