Token partition tree check failure (fuzzer finding)

[hzeller]

Test case

This input file testcase-5103868086976512.gz

Results in this CHECK failure:

$ bazel-bin/verilog/tools/formatter/verible-verilog-format <(zcat /tmp/testcase-5103868086976512.gz)
F1206 08:14:21.240898 2597779 token_partition_tree.cc:64] Check failed: parent_end == children_end (0 vs. 4) node:
{ (>>>>[<auto>], policy: wrap) @{0,1}, (origin: "(1  //
,)")
  { (>>>>[(], policy: fit-else-expand, (origin: "(")) }
  { (>>>>>>>>[<auto>], policy: wrap) @{0,1,1}, (origin: "1  //
,")
    { (>>>>>>>>[1 //], policy: fit-else-expand, (origin: "1")) }
  }
  { (>>>>[,], policy: uninitialized) }
}
*** Check failure stack trace: ***
    @     0x555555642ab9  absl::log_internal::LogMessage::SendToLog()
    @     0x555555643069  absl::log_internal::LogMessageFatal::~LogMessageFatal()
    @     0x555555574ca4  verible::VerifyTreeNodeFormatTokenRanges()
    @     0x5555555dd3ff  verible::VerifyFullTreeFormatTokenRanges()
    @     0x5555555ddadc  verible::MergeLeafIntoNextLeaf()
    @     0x5555555b1ce0  verilog::formatter::TreeUnwrapper::ReshapeTokenPartitions()
    @     0x5555555b684d  verilog::formatter::TreeUnwrapper::Visit()
    @     0x5555555cd69a  verible::TreeUnwrapper::TraverseChildren()
    @     0x5555555cd7cd  verible::TreeUnwrapper::VisitIndentedChildren()
    @     0x5555555cd861  verible::TreeUnwrapper::VisitIndentedSection()
    @     0x5555555b5e1a  verilog::formatter::TreeUnwrapper::SetIndentationsAndCreatePartitions()
    @     0x5555555b6827  verilog::formatter::TreeUnwrapper::Visit()
    @     0x5555555cd69a  verible::TreeUnwrapper::TraverseChildren()
    @     0x5555555cd7cd  verible::TreeUnwrapper::VisitIndentedChildren()
    @     0x5555555cd861  verible::TreeUnwrapper::VisitIndentedSection()
    @     0x5555555b5ebc  verilog::formatter::TreeUnwrapper::SetIndentationsAndCreatePartitions()
    @     0x5555555b6827  verilog::formatter::TreeUnwrapper::Visit()
    @     0x5555555cd69a  verible::TreeUnwrapper::TraverseChildren()
    @     0x5555555b5f2b  verilog::formatter::TreeUnwrapper::SetIndentationsAndCreatePartitions()
    @     0x5555555b6827  verilog::formatter::TreeUnwrapper::Visit()
    @     0x5555555cce24  verible::TreeUnwrapper::Unwrap()
    @     0x55555558f15e  verilog::formatter::Formatter::Format()
    @     0x555555590d17  verilog::formatter::FormatVerilog()
    @     0x555555591385  verilog::formatter::FormatVerilog()
    @     0x5555555915d8  verilog::formatter::FormatVerilog()
    @     0x55555557ebb0  main
    @     0x7ffff782920a  (unknown)
Aborted

[fangism]

FYI: b/259099842 for this issue was just automatically closed as not-reproducible

[hzeller]

Still reproduces with the testcase downloadable above.