The infinite loops in the HS parser are in transpiled native OCaml code,
not in the VM or CEK step loop. Neither step counters (in cek_step_loop,
cek_step, trampoline) nor VM instruction checks caught them because
the loops are in direct OCaml recursion.
Fix: SIGALRM handler raises Eval_error to break out of native loops.
Also sets step_limit flag to catch VM loops. Combined approach handles
both native OCaml recursion (alarm+raise) and VM bytecode (step check).
The alarm+raise can become unreliable after ~13 timeouts in a single
process, but handles the common case well. Reverts the fork-based
approach which lost inter-test state.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
giles
e3eb46d0dc