Currently, dsymutil treats the DW_OP_convert operand as absolute instead
of CU relative, as described by in the DWARFv5 spec, 2.5.1.6:
"[DW_OP_convert] takes one operand, which is an unsigned LEB128 integer
that represents the offset of a debugging information entry in the current
compilation unit"
This patch makes dsymutil correctly treat the offset as CU relative,
preventing a crash when there are multiple compilation units.
Big thanks to Akira Hatanaka for figuring out this issue and providing
both a reduced test case and a proposed fix.
a17c90daf2