Evaluation of invalid Function crashes Scala #21952
Description
Compiler version
3.5.2
Minimized code
When running in scala-cli, the following crashes:
(new Function[(Int, Int), Int] {def apply(a: Int, b: Int): Int = a * b})(2, 3)Of course, the above code is invalid, there should be a single tuple argument to apply. The unexpected result is that Scala crashes altogether instead of just throwing an exception.
It should be replaced with any of the following, which both work:
(new Function[(Int, Int), Int] {def apply(a: (Int, Int)): Int = a._1 * a._2})(2, 3)
(new Function2[Int, Int, Int] {def apply(a: Int, b: Int): Int = a * b})(2, 3)Output (click arrow to expand)
unhandled exception while running MegaPhase{crossVersionChecks, firstTransform, checkReentrant, elimPackagePrefixes, cookComments, checkLoopingImplicits, betaReduce, inlineVals, expandSAMs, elimRepeated, refchecks} on rs$line$1
An unhandled exception was thrown in the compiler.
Please file a crash report here:
https://github.com/scala/scala3/issues/new/choose
For non-enriched exceptions, compile with -Xno-enrich-error-messages.
while compiling: rs$line$1
during phase: MegaPhase{crossVersionChecks, firstTransform, checkReentrant, elimPackagePrefixes, cookComments, checkLoopingImplicits, betaReduce, inlineVals, expandSAMs, elimRepeated, refchecks}
mode: Mode(ImplicitsEnabled,ReadPositions,Interactive)
library version: version 2.13.14
compiler version: version 3.5.2
settings: -Xcook-docs true -Xread-docs true -classpath /home/beaver/.my/java/scala3/maven2/org/scala-lang/scala3-library_3/3.5.2/scala3-library_3-3.5.2.jar:/home/beaver/.my/java/scala3/maven2/org/scala-lang/scala-library/2.13.14/scala-library-2.13.14.jar -d <REPL compilation output>
Exception in thread "main" java.lang.UnsupportedOperationException: tail of empty list
at scala.collection.immutable.Nil$.tail(List.scala:665)
at scala.collection.immutable.Nil$.tail(List.scala:662)
at dotty.tools.dotc.core.Substituters$.substSym(Substituters.scala:87)
at dotty.tools.dotc.core.Types$Type.substSym(Types.scala:1942)
at dotty.tools.dotc.ast.TreeTypeMap$$anon$2.apply(TreeTypeMap.scala:75)
at dotty.tools.dotc.ast.TreeTypeMap.mapType(TreeTypeMap.scala:76)
at dotty.tools.dotc.ast.TreeTypeMap.transform(TreeTypeMap.scala:110)
at dotty.tools.dotc.transform.BetaReduce$.reduceApplication(BetaReduce.scala:151)
at dotty.tools.dotc.transform.BetaReduce$.recur$1(BetaReduce.scala:82)
at dotty.tools.dotc.transform.BetaReduce$.apply(BetaReduce.scala:95)
at dotty.tools.dotc.transform.BetaReduce.transformApply(BetaReduce.scala:44)
at dotty.tools.dotc.transform.MegaPhase.goApply(MegaPhase.scala:681)
at dotty.tools.dotc.transform.MegaPhase.goApply(MegaPhase.scala:682)
at dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:297)
at dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
at dotty.tools.dotc.transform.MegaPhase.mapValDef$1(MegaPhase.scala:251)
at dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:256)
at dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:452)
at dotty.tools.dotc.transform.MegaPhase.loop$1(MegaPhase.scala:465)
at dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:465)
at dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:376)
at dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
at dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:272)
at dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:452)
at dotty.tools.dotc.transform.MegaPhase.loop$1(MegaPhase.scala:465)
at dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:465)
at dotty.tools.dotc.transform.MegaPhase.mapPackage$1(MegaPhase.scala:396)
at dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:399)
at dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
at dotty.tools.dotc.transform.MegaPhase.transformUnit(MegaPhase.scala:481)
at dotty.tools.dotc.transform.MegaPhase.run(MegaPhase.scala:493)
at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:380)
at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
at scala.collection.immutable.List.foreach(List.scala:334)
at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:373)
at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:343)
at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
at dotty.tools.dotc.Run.runPhases$1(Run.scala:336)
at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:384)
at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:396)
at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:69)
at dotty.tools.dotc.Run.compileUnits(Run.scala:396)
at dotty.tools.dotc.Run.compileUnits(Run.scala:288)
at dotty.tools.repl.ReplCompiler.compile(ReplCompiler.scala:88)
at dotty.tools.repl.ReplDriver.compile(ReplDriver.scala:321)
at dotty.tools.repl.ReplDriver.interpret(ReplDriver.scala:283)
at dotty.tools.repl.ReplDriver.loop$1(ReplDriver.scala:196)
at dotty.tools.repl.ReplDriver.runUntilQuit$$anonfun$1(ReplDriver.scala:199)
at dotty.tools.repl.ReplDriver.withRedirectedOutput(ReplDriver.scala:238)
at dotty.tools.repl.ReplDriver.runBody$$anonfun$1(ReplDriver.scala:212)
at dotty.tools.runner.ScalaClassLoader$.asContext(ScalaClassLoader.scala:80)
at dotty.tools.repl.ReplDriver.runBody(ReplDriver.scala:212)
at dotty.tools.repl.ReplDriver.runUntilQuit(ReplDriver.scala:199)
at dotty.tools.repl.ReplDriver.tryRunning(ReplDriver.scala:136)
at dotty.tools.repl.Main$.main(Main.scala:7)
at dotty.tools.repl.Main.main(Main.scala)Note
Note also that simply creating the function only throws an exception, without crashing:
new Function[(Int, Int), Int] {def apply(a: Int, b: Int): Int = a * b}Output:
-- Error: ----------------------------------------------------------------------------------------------------------------------------------
1 |new Function[(Int, Int), Int] {def apply(a: Int, b: Int): Int = a * b}
|^
|object creation impossible, since def apply(v1: T1): R in trait Function1 in package scala is not defined
1 error found