Truffleruby: TypeError TruffleRuby doesn't have a case for the StringNodesFactory$MakeStringNodeGen node with values of type null

[ivoanjo]

Environment:

• truffleruby 20.3.0, like ruby 2.6.6, GraalVM CE Native [x86_64-darwin]
• Darwin COMP-C02DT18AML87 19.6.0 Darwin Kernel Version 19.6.0: Tue Nov 10 00:10:30 PST 2020; root:xnu-6153.141.10~1/RELEASE_X86_64 x86_64 i386 MacBookPro16,2 Darwin

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Hey!

Just found this weird issue when trying to read the base_label of the backtrace locations of a reference processor thread. The issue doesn't seem to happen with regular threads.

TypeError (TruffleRuby doesn't have a case for the org.truffleruby.core.string.StringNodesFactory$MakeStringNodeGen node with values of type null org.jcodings.specific.UTF8Encoding org.truffleruby.core.rope.CodeRange)
    from org.truffleruby.core.string.StringNodesFactory$MakeStringNodeGen.executeAndSpecialize(StringNodesFactory.java:305)
    from org.truffleruby.core.string.StringNodesFactory$MakeStringNodeGen.executeMake(StringNodesFactory.java:220)
    from org.truffleruby.core.thread.ThreadBacktraceLocationNodes$BaseLabelNode.label(ThreadBacktraceLocationNodes.java:121)
    from org.truffleruby.core.thread.ThreadBacktraceLocationNodesFactory$BaseLabelNodeFactory$BaseLabelNodeGen.executeAndSpecialize(ThreadBacktraceLocationNodesFactory.java:419)
    from org.truffleruby.core.thread.ThreadBacktraceLocationNodesFactory$BaseLabelNodeFactory$BaseLabelNodeGen.execute(ThreadBacktraceLocationNodesFactory.java:404)
    from org.truffleruby.language.arguments.CheckArityNode.execute(CheckArityNode.java:41)
    from org.truffleruby.language.methods.ExceptionTranslatingNode.execute(ExceptionTranslatingNode.java:33)
    from org.truffleruby.language.RubyRootNode.execute(RubyRootNode.java:64)
    from org.graalvm.compiler.truffle.runtime.OptimizedCallTarget.executeRootNode(OptimizedCallTarget.java:557)

I'm not sure what in my environment triggers the creation of a reference processor thread, but I did notice that irb also started one, so my minimal test case makes use of irb:

echo "puts Thread.list.find { |t| t.to_s =~ /reference-processor/ }.backtrace_locations.first.base_label" | irb

Let me know if I can provide any more info! :)
(For context, this was extracted from one of the tests on https://github.com/DataDog/dd-trace-rb)

[eregon]

Thanks for the report.
https://github.com/oracle/truffleruby/blob/f01379be2e700102436a5aaa52531fd03d02f970/src/main/java/org/truffleruby/core/thread/ThreadNodes.java#L195 passes the wrong value for currentNode (it passes the node of the current thread and not of the target thread), which causes this issue. I'll fix it.

[eregon]

Fixed in a5afb7a164e3318284e9c76d3448d3ab4baf1a7e.

[ivoanjo]

That was FAST -- thanks!