0.6.0

Highlights

• Lua 5.5 support. The C module builds and passes the test suite on Lua
  5.5; Lua 5.1–5.4 and LuaJIT remain supported.
• Hardened against malicious input. Deeply nested messages now fail with
  message too complex instead of exhausting the C stack, and pb.load()
  rejects descriptors nested deeper than 100 levels instead of recursing
  without a bound. Thanks to Brian Lee (Team Atlanta) for the vulnerability
  report and his review of the decode fix.
• protoc.lua descriptor parity. proto3 optional now produces the same
  descriptors as protoc (synthetic oneofs), and descriptor output matches
  protoc for escapes, float exponents, ranges, import public and inline
  options. A failed parse no longer leaves types behind.
• New protoc_test.lua with 65 cases: 53 passing and 12 tracked
  known issues (run lua protoc_test.lua -x known_issue for the healthy
  subset).

Fixes

• pb.buffer:result() and pb.slice:result() return "" for an empty
  buffer/slice instead of raising.
• pb.buffer.pack("c", "") accepts zero-length slices (it used to raise
  "out of memory").
• Negative enum values (e.g. -1) are no longer lost from type tables.
• buffer:pack reports an invalid format before consuming its arguments;
  slice:unpack("+", n) clamps to the start of the slice instead of reading
  before it.
• Undefined behavior fixed in the type-table hash (signed overflow), the
  packed repeated and map decode paths, and the encoder scratch buffer.
  PBT_DEADKEY and its dead table slot are gone.

protoc.lua

• proto3 optional is accepted by default; p.proto3_optional = false
  restores the old rejection. Synthetic oneofs are named _field (no doubled
  underscore), get an X prefix on collision, and are ordered after real
  oneofs. Extension fields get proto3_optional without oneof_index.
• Descriptor output fixes: default_value = "nil" for fields with inline
  options, spurious empty options messages, \xNN/\NNN escapes, float
  exponents such as 1e-3, exclusive range ends for extension and reserved
  ranges (inclusive for enum ranges), and a plain import no longer recorded
  as a public dependency.
• Parser robustness: failed parses roll back registered types,
  include_imports emits each file once, import cycles and self-imports are
  reported, unknown_import accepts a Lua pattern, unknown_type may return
  a type name plus kind, and duplicate nested enum names/numbers are rejected.

Tooling and internals

• .clang-format is now checked in; pb.h/pb.c were reformatted to 80
  columns with no behavior change, and static analyzer findings were fixed.
• CI tests Lua 5.4.8 and 5.5.0 alongside 5.1–5.3 and LuaJIT.

Breaking changes

• p.experimental_allow_proto3_optional was removed; use
  p.proto3_optional (proto3 optional is allowed by default).
• The internal lpb_pushunpackdef symbol is static again and no longer
  exported from pb.so (it was never declared in pb.h).
• buffer:pack validates the format before its arguments, so an invalid
  format now raises a format error rather than an argument error.

Full Changelog: 0.5.3...0.6.0