`compiletime.testing.typeCheckErrors` can result in `UTF8 string too large` in JVM codegen

[WojciechMazur]

Based on the OpenCB failure in plokhotnyuk/jsoniter-scala - build logs

If the execution of macro results in StackOverflow or other exception with long stack trace, it might be too long when reaching the JVM backend - at this point the codegen would fail with exception

We should either trim the output of such macro, or detect it and fail early. Otherwise it's hard to discover exact place where failing macro was used.

Compiler version

3.8
3.3 LTS
All Scala versions

Minimized code

def Test = scala.compiletime.testing.typeCheckErrors("stackOverflowMacro")

import scala.quoted.*

transparent inline def stackOverflowMacro: Int = ${ StackOverflowMacro.impl }

object StackOverflowMacro:
    def impl(using Quotes): Expr[Int] =  '{ ${impl} + ${impl} }
    

Output

> scala compile test.scala test.macro.scala -S 3.8.0-RC2 --server=false
java.lang.IllegalArgumentException: UTF8 string too large
        at scala.tools.asm.ByteVector.putUTF8(ByteVector.java:255)
        at scala.tools.asm.SymbolTable.addConstantUtf8(SymbolTable.java:800)
        at scala.tools.asm.SymbolTable.addConstantUtf8Reference(SymbolTable.java:1053)
        at scala.tools.asm.SymbolTable.addConstantString(SymbolTable.java:630)
        at scala.tools.asm.SymbolTable.addConstant(SymbolTable.java:500)
        at scala.tools.asm.MethodWriter.visitLdcInsn(MethodWriter.java:1281)
        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:751)
        at scala.tools.asm.tree.MethodNode.accept(MethodNode.java:649)
        at scala.tools.asm.tree.ClassNode.accept(ClassNode.java:468)
        at dotty.tools.backend.jvm.PostProcessor.serializeClass(PostProcessor.scala:101)
        at dotty.tools.backend.jvm.PostProcessor.sendToDisk(PostProcessor.scala:37)
        at dotty.tools.backend.jvm.GeneratedClassHandler$WritingClassHandler.postProcessUnit$$anonfun$1$$anonfun$1$$anonfun$1(GeneratedClassHandler.scala:94)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.immutable.List.foreach(List.scala:327)
        at dotty.tools.backend.jvm.GeneratedClassHandler$WritingClassHandler.postProcessUnit$$anonfun$1$$anonfun$1(GeneratedClassHandler.scala:94)
        at dotty.tools.backend.jvm.GeneratedClassHandler$WritingClassHandler.postProcessUnit$$anonfun$1$$anonfun$adapted$1(GeneratedClassHandler.scala:96)
        at dotty.tools.backend.jvm.PostProcessorFrontendAccess$Impl.withThreadLocalReporter(PostProcessorFrontendAccess.scala:140)
        at dotty.tools.backend.jvm.GeneratedClassHandler$WritingClassHandler.postProcessUnit$$anonfun$1(GeneratedClassHandler.scala:96)
        at dotty.tools.backend.jvm.GeneratedClassHandler$WritingClassHandler.postProcessUnit$$anonfun$adapted$1(GeneratedClassHandler.scala:96)
        at scala.concurrent.Future$.apply$$anonfun$1(Future.scala:692)
        at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:503)
        at dotty.tools.backend.jvm.GeneratedClassHandler$.SyncWritingClassHandler$superArg$1$$anonfun$1(GeneratedClassHandler.scala:146)
        at scala.concurrent.impl.ExecutionContextImpl.execute(ExecutionContextImpl.scala:22)
        at scala.concurrent.impl.Promise$Transformation.submitWithValue(Promise.scala:465)
        at scala.concurrent.impl.Promise$DefaultPromise.submitWithValue(Promise.scala:374)
        at scala.concurrent.impl.Promise$DefaultPromise.dispatchOrAddCallbacks(Promise.scala:325)
        at scala.concurrent.impl.Promise$DefaultPromise.map(Promise.scala:185)
        at scala.concurrent.Future$.apply(Future.scala:692)
        at dotty.tools.backend.jvm.GeneratedClassHandler$WritingClassHandler.postProcessUnit(GeneratedClassHandler.scala:96)
        at dotty.tools.backend.jvm.GeneratedClassHandler$WritingClassHandler.process(GeneratedClassHandler.scala:82)
        at dotty.tools.backend.jvm.CodeGen.genUnit(CodeGen.scala:122)
        at dotty.tools.backend.jvm.GenBCode.run(GenBCode.scala:90)
        at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:386)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.immutable.List.foreach(List.scala:327)
        at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:379)
        at dotty.tools.backend.jvm.GenBCode.runOn(GenBCode.scala:98)
        at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:380)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1327)
        at dotty.tools.dotc.Run.runPhases$1(Run.scala:373)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$1$$anonfun$2(Run.scala:420)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$1$$anonfun$adapted$1(Run.scala:420)
        at scala.Function0.apply$mcV$sp(Function0.scala:45)
        at dotty.tools.dotc.Run.showProgress(Run.scala:482)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:420)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:432)
        at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:69)
        at dotty.tools.dotc.Run.compileUnits(Run.scala:432)
        at dotty.tools.dotc.Run.compileUnits(Run.scala:325)
        at dotty.tools.dotc.Run.compileSuspendedUnits(Run.scala:446)
        at dotty.tools.dotc.Driver.finish(Driver.scala:64)
        at dotty.tools.dotc.Driver.doCompile(Driver.scala:39)
        at dotty.tools.dotc.Driver.process(Driver.scala:213)
        at dotty.tools.dotc.Driver.process(Driver.scala:181)
        at dotty.tools.dotc.Driver.process(Driver.scala:193)
        at dotty.tools.dotc.Driver.main(Driver.scala:223)
        at dotty.tools.dotc.Main.main(Main.scala)
Error while emitting test$package$
UTF8 string too large
1 error found

Expectation

[hamzaremmal]

There was an attempt by me last year #19622. The signatures are encoded as UTF8 strings so it is the same underlying issue.

If the execution of macro results in StackOverflow or other exception with long stack trace, it might be too long when reaching the JVM backend - at this point the codegen would fail with exception

If we had an error, we shouldn't even have reached the backend. I don't see exactly what you mean here.

We should either trim the output of such macro,

That is a bad idea, the closest to this we can do is remove the compiler part of it or such not include the stack trace.

scala.compiletime.testing.typeCheckErrors("stackOverflowMacro")

This is not a macro, it is a compiler intrinsic and I doubt you need a macro to trigger the stack overflow (could be minimized further).