UTF8 string too large when comparing 2 big objects

This issue was copied over from: https://github.com/disneystreaming/weaver-test/issues/760
It was opened by: PaNaVTEC

The following attached test will crash when executing, while this is a toy example it can happen if you try to compare equality on two massive objects, I managed to replicate it in a real world™ scenario by trying to compare 2 stripe invoices. The crash goes away if the long inlined object (string in the example below) is extracted to a local variable and you do:

// Working example
val expectedStr = "... my long str ... "
"" == expectedStr

Affected example: https://pastebin.com/0d48ACec

Trace:

java.lang.IllegalArgumentException: UTF8 string too large
	at scala.tools.asm.ByteVector.putUTF8(ByteVector.java:255)
	at scala.tools.asm.SymbolTable.addConstantUtf8(SymbolTable.java:774)
	at scala.tools.asm.SymbolTable.addConstantUtf8Reference(SymbolTable.java:1007)
	at scala.tools.asm.SymbolTable.addConstantString(SymbolTable.java:604)
	at scala.tools.asm.SymbolTable.addConstant(SymbolTable.java:474)
	at scala.tools.asm.MethodWriter.visitLdcInsn(MethodWriter.java:1280)
	at scala.tools.asm.tree.LdcInsnNode.accept(LdcInsnNode.java:75)
	at scala.tools.asm.tree.InsnList.accept(InsnList.java:144)
	at scala.tools.asm.tree.MethodNode.accept(MethodNode.java:749)
	at scala.tools.asm.tree.MethodNode.accept(MethodNode.java:647)
	at scala.tools.asm.tree.ClassNode.accept(ClassNode.java:468)
	at dotty.tools.backend.jvm.PostProcessor.serializeClass(PostProcessor.scala:71)
	at dotty.tools.backend.jvm.PostProcessor.postProcessAndSendToDisk$$anonfun$2(PostProcessor.scala:31)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.IterableOnceOps.foreach(IterableOnce.scala:576)
	at scala.collection.IterableOnceOps.foreach$(IterableOnce.scala:574)
	at scala.collection.AbstractIterable.foreach(Iterable.scala:933)
	at scala.collection.IterableOps$WithFilter.foreach(Iterable.scala:903)
	at dotty.tools.backend.jvm.PostProcessor.postProcessAndSendToDisk(PostProcessor.scala:48)
	at dotty.tools.backend.jvm.GenBCode.run(GenBCode.scala:80)
	at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:327)
	at scala.collection.immutable.List.map(List.scala:246)
	at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:331)
	at dotty.tools.backend.jvm.GenBCode.runOn(GenBCode.scala:87)
	at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:246)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
	at dotty.tools.dotc.Run.runPhases$1(Run.scala:262)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:270)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:279)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:71)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:279)
	at dotty.tools.dotc.Run.compileSources(Run.scala:194)
	at dotty.tools.dotc.Run.compile(Run.scala:179)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
	at dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:136)
	at dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
	at sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:193)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:248)
	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:183)
	at sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:163)
	at sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239)
	at sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:163)
	at sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:211)
	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:534)
	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:534)
	at sbt.internal.inc.Incremental$.$anonfun$apply$5(Incremental.scala:180)
	at sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:178)
	at sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:464)
	at sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:116)
	at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
	at sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
	at sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:263)
	at sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:419)
	at sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:506)
	at sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:406)
	at sbt.internal.inc.Incremental$.apply(Incremental.scala:172)
	at sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:534)
	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:488)
	at sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
	at sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:425)
	at sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
	at sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2371)
	at sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2321)
	at sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:31)
	at sbt.internal.io.Retry$.apply(Retry.scala:47)
	at sbt.internal.io.Retry$.apply(Retry.scala:29)
	at sbt.internal.io.Retry$.apply(Retry.scala:24)
	at sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:31)
	at sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2319)
	at scala.Function1.$anonfun$compose$1(Function1.scala:49)
	at sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:63)
	at sbt.std.Transform$$anon$4.work(Transform.scala:69)
	at sbt.Execute.$anonfun$submit$2(Execute.scala:283)
	at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:24)
	at sbt.Execute.work(Execute.scala:292)
	at sbt.Execute.$anonfun$submit$1(Execute.scala:283)
	at sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265)
	at sbt.CompletionService$$anon$2.call(CompletionService.scala:65)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:840)

Start by reproducing the affected test from the linked Pastebin example, comparing the inline large string with the local-variable workaround. Trace the compilation failure through the dotty JVM backend and the scala.tools.asm UTF8 error; done means the inline comparison compiles without the crash while equality behavior remains correct.