Compiler crashes when named tuple with `apply` field is used

[road21]

Compiler version

3.7.2

Minimized code

(apply = () => 1)(())

Output

Compiler crashes with error:

....
dotty.tools.dotc.typer.Typer.typedSelect(Typer.scala:1103)
dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:3621)
dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3733)
dotty.tools.dotc.typer.Typer.typed(Typer.scala:3811)
dotty.tools.dotc.typer.Typer.typed(Typer.scala:3816)
dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3927)
dotty.tools.dotc.typer.Applications.realApply$1(Applications.scala:1098)
dotty.tools.dotc.typer.Applications.typedApply(Applications.scala:1299)
dotty.tools.dotc.typer.Applications.typedApply$(Applications.scala:470)
dotty.tools.dotc.typer.Typer.typedApply(Typer.scala:155)
dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:3646)
....

Expectation

No crash

[som-snytt]

That's a good one.

To clarify, it is StackOverflowError.

This message is not helpful to a beginner.

scala> (take = 17, y = 42).take(1)
-- [E050] Type Error: ----------------------------------------------------------
1 |(take = 17, y = 42).take(1)
  |^^^^^^^^^^^^^^^^^^^
  |method apply in object NamedTuple does not take more parameters

Is that because the extension methods are inline?

The translation of named tuples to instances of NamedTuple is fixed by the specification and therefore known to the programmer.

Ah, it's my fault for not knowing.

[Gedochao]

Last good release: 3.7.0-RC1-bin-20250309-2f639e2-NIGHTLY
First bad release: 3.7.0-RC1-bin-20250312-3fe9304-NIGHTLY
b9464b4 is the first bad commit (#22753)
cc @WojciechMazur
Also, cc @aherlihy @odersky for good measure, as the crash seems to be tightly connected to named tuples' implementation

[Gedochao]

Some more output:

Exception while compiling /Users/pchabelski/IdeaProjects/scala-cli-tests-3/scala-cli-tests-3/compiler-repro/repro.scala

  An unhandled exception was thrown in the compiler.
  Please file a crash report here:
  https://github.com/scala/scala3/issues/new/choose
  For non-enriched exceptions, compile with -Xno-enrich-error-messages.


     while compiling: <no file>
        during phase: parser
                mode: Mode()
     library version: version (unknown)
    compiler version: version 3.8.0-RC1-bin-20250923-18f22ab-NIGHTLY-git-18f22ab
            settings: -classpath /Users/pchabelski/Library/Caches/Coursier/v1/https/repo.scala-lang.org/artifactory/maven-nightlies/org/scala-lang/scala3-library_3/3.8.0-RC1-bin-20250923-18f22ab-NIGHTLY/scala3-library_3-3.8.0-RC1-bin-20250923-18f22ab-NIGHTLY.jar:/Users/pchabelski/Library/Caches/Coursier/v1/https/repo.scala-lang.org/artifactory/maven-nightlies/org/scala-lang/scala-library/3.8.0-RC1-bin-20250923-18f22ab-NIGHTLY/scala-library-3.8.0-RC1-bin-20250923-18f22ab-NIGHTLY.jar -d /Users/pchabelski/IdeaProjects/scala-cli-tests-3/scala-cli-tests-3/compiler-repro/.scala-build/compiler-repro_72e168a3af-9acd81c9bc/classes/main -sourceroot /Users/pchabelski/IdeaProjects/scala-cli-tests-3/scala-cli-tests-3/compiler-repro

Exception in thread "main" java.lang.StackOverflowError
        at dotty.tools.dotc.core.TypeOps$.simplify(TypeOps.scala:145)
        at dotty.tools.dotc.core.Types$Type.simplified(Types.scala:2132)
        at dotty.tools.dotc.typer.Typer.simplify(Typer.scala:3802)
        at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3786)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3870)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3875)
        at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3986)
        at dotty.tools.dotc.typer.Typer.typeSelectOnTerm$1(Typer.scala:1067)
        at dotty.tools.dotc.typer.Typer.typedSelect(Typer.scala:1121)
        at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:3664)
        at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3782)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3870)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3875)
        at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3986)
        at dotty.tools.dotc.typer.Applications.realApply$1(Applications.scala:1109)
        at dotty.tools.dotc.typer.Applications.typedApply(Applications.scala:1336)
        at dotty.tools.dotc.typer.Applications.typedApply$(Applications.scala:470)
        at dotty.tools.dotc.typer.Typer.typedApply(Typer.scala:162)
        at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:3689)
        at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3783)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3870)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3875)
        at dotty.tools.dotc.typer.Typer.tryNamedTupleSelection$1(Typer.scala:855)
        at dotty.tools.dotc.typer.Typer.typedSelectWithAdapt(Typer.scala:959)
        at dotty.tools.dotc.typer.Typer.typeSelectOnTerm$1(Typer.scala:1068)
        at dotty.tools.dotc.typer.Typer.typedSelect(Typer.scala:1121)
        at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:3664)
        at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3782)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3870)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:3875)
        at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3986)
       (...)

[WojciechMazur]

With experimental named tuples enabled it can be tracked up to 3.5.0, so it's not related to their standardisation in 3.7.0

import scala.language.experimental.namedTuples
(apply = () => 1)(())

[Gedochao]

With experimental named tuples enabled it can be tracked up to 3.5.0, so it's not related to their standardisation in 3.7.0

import scala.language.experimental.namedTuples
(apply = () => 1)(())

I mean... it is and it isn't.
I'd still consider it a regression, since stabilising it introduced a crash.
Anyway, fair.