FA-89974 / Bytecode virtual machines / Member archive

Exception tables: finally entries never match · case 04

finally blocks are skipped and errors escape methods that should run cleanup code.

Member previewVariant 4 · 3 implementations · 10 checks per implementation

Case contract

frames are ordered outermost first; the innermost frame carries the faulting pc, every caller carries the return address "ret" and the invoke opcode "via" (invokeinterface and invokedynamic are 5 bytes, other invokes 3), and the lookup pc is the invoke's own address. Each table entry [start, end, handler, type] covers start <= pc < end; entries are tried in table order; type None catches anything, otherwise the thrown type or any ancestor (parents map) must equal it. Return handler, number of frames unwound and the operand stack at the handler (cleared, then the exception pushed).

Why this case matters

Exception dispatch correctness depends on half-open ranges, table order, type hierarchy and pc attribution.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
any-type entry catches errors	`{"handler": null, "stack": [], "unwound": 1}`	`{"handler": 400, "stack": ["StackOverflowError"], "unwound": 0}`	Failed

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