Artifact Description [7fc5244568]

Artifact 7fc52445688751bb8af30462549650660bcdbadabef54d892b6505d628248d0b:

• File src/merge3.zig
  • 2026-07-19 01:54:32 — part of check-in [21ca364fb3] on branch release-0.1 — Add merge3_properties: algebraic-property fuzzing over the three-way merge

    Silent merge corruption is the worst failure a version-control system can have — it produces a tree that looks right — and merge3 had no fuzz target. This adds one, driving the merger with generated base/current/other triples and asserting the properties that must hold for any input.

    Oracle 4 (no invented lines) needs a carve-out, because the merger is supposed to fabricate lines inside a conflict envelope. That carve-out is only sound if the recorded spans really are envelopes, so expectNoInventedLines validates the claim before subtracting anything: each span must be in-bounds, open at a line boundary with conflict_sentinel, close with conflict_terminator, start at or after the previous span's end, and carry no second terminator inside it.

    The ordering and interior-terminator checks are load-bearing, not belt-and- braces. inAnySpan matches on overlap, so an over-long span exempts every output line up to its end. End-pinning alone admits a single span stretched from the first envelope's start to the last one's end — it opens and closes correctly and overlaps nothing — which would exempt the clean lines between two envelopes from the oracle entirely. closes_once catches that case on the first envelope's terminator. merge3 asserts ordering itself, but only under runtime_safety, which a ReleaseFast sweep — the build a fuzz run uses — erases; this loop holds in every optimize mode.

    merge3.zig gains one export: conflict_terminator, the closing counterpart of the existing conflict_sentinel, with a comptime tripwire pinning its shape. Additive only, no behavior change — it lets the oracle pin both envelope ends against the module that produces them instead of re-typing the literal, so the two cannot drift apart.

    Battery green in the worktree: zig fmt --check ., zig build, zig build test, zig build e2e, zig build dst (6 seeds x 1000 steps). The new target runs clean at seed 1 over 2000 rounds; no bug was found, so no regression seed is pinned. (user: dmestas, size: 29263) [annotate] [blame] [check-ins using]

  • 2026-07-19 01:58:02 — part of check-in [08e7c6d6f1] on branch trunk — Merge release-0.1: merge3_properties algebraic-property fuzz (P4-F7)

    Lands the last of the seven 0.1.0 release blockers. merge3 — the three-way merge — had no fuzz target, and silent merge corruption is the worst failure a version-control system can have, because it produces a tree that looks right.

    The merged tree was re-verified on trunk after the merge, not inherited from the branch: zig fmt --check ., zig build, and zig build test all exit 0. The merge reported no conflicts and touched four files; fossil extras is empty, so nothing referenced went unadded. The conflict-marker sequences a repo-wide grep reports in src/merge3.zig and src/e2e.zig are that module's own sentinel constants and the tests asserting on them, not merge residue.

    Landed by hand rather than by the release workflow: its TigerStyle gate spent its three-round budget on this diff and halted without a confirming pass. The final round's two blockers were real — a zig fmt failure and an oracle hole where conflict spans were validated individually but never as ordered and disjoint, which would have let one widened span exempt every line from oracle 4 — and both were fixed by the round that followed. Verified here before landing: fmt clean, the ordered/closes_once checks present, and merge3_properties running clean at seed 1 over 2000 rounds. (user: dmestas, size: 29263) [annotate] [blame] [check-ins using]