fix: substConstants serializer-level parity: body-verbatim, OOB no-op, first-wins, v3 size-gate (match sigma-state)#871
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`SubstConstants` eval full-parsed the script bytes (`ErgoTree:: sigma_parse_bytes`) and errored when a requested position was >= the tree's constant count. sigma-state's `ErgoTreeSerializer. substituteConstants` is byte-surgery: it parses only the header and constants segment, keeps the tree body verbatim (never deserializing it), substitutes constants at in-range positions, and silently no-ops out-of-range ones. sigma-rust therefore rejected scripts the JVM accepts -- an out-of-range position, or an unparseable tree body -- a latent consensus fork (not seen on mainnet). Add `ErgoTree::substitute_constants` mirroring the Scala serializer (header + constants parsed, body bytes kept raw, OOB positions dropped, first position per index wins) and call it from `SubstConstants::eval`. Verified byte-exact against SANTA's JVM-blessed v5 vectors (`substConstants_equivalence.json`): the five out-of-range entries (incl. `[0,0,8,-45]`, whose body the full parser rejects with InvalidTypeCode) return the input unchanged; in-range substitution stays covered by the existing proptests. New `substitute_constants_oob_is_noop` regression test. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
ErgoTree::substitute_constants re-emitted the tree-size slot whenever the template header has_size bit was set. sigma-state's ErgoTreeSerializer.substituteConstants re-emits it only when the evaluation's ErgoTree version is >= V3 (the V6 soft-fork isV3OrLaterErgoTreeVersion gate); for v<=2 the slot is dropped even though the bit stays set. Thread the evaluation's tree_version (ctx.tree_version()) into the fn and gate the size emit on it. Completes the substConstants serializer-level parity (body-verbatim and first-wins were already handled here). The v<=2 hasSize path is not mainnet-reachable, so it is covered by a unit test (v2 drops / v3 keeps the slot) certified against the Scala source rather than a blessed vector. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Addendum: scope grew beyond the original out-of-range no-op to the full serializer-level substConstants rewrite (title updated). All four behaviors match sigma-state's ErgoTreeSerializer.substituteConstants. The v3 size-gate isn't mainnet-reachable, so it's covered by a unit test rather than a blessed vector. |
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SubstConstantsfull-parsed the script bytes and errored when a position was >= the tree's constant count. sigma-state'sErgoTreeSerializer.substituteConstantsis byte-surgery: it parses only the header + constants, keeps the body verbatim (never deserializing it), substitutes in-range positions and no-ops out-of-range ones. sigma-rust thus rejected scripts the JVM accepts — an OOB position or an unparseable body — a latent consensus fork (not seen on mainnet).Adds
ErgoTree::substitute_constantsmirroring the Scala serializer;SubstConstants::evalcalls it. Verified byte-exact vs JVM-blessed v5 vectors (5 OOB entries, incl. one with an unparseable body, return input unchanged); in-range covered by proptests. Newsubstitute_constants_oob_is_nooptest.