~bigbes/tarantool

tarantool-protobuf

ref: 7a77bcfc1c6f4d29600ee7636ff174162c40087a tarantool-protobuf/cmd/protoc-gen-tarantool/internal d---------
a6eebdb3 — Eugene Blikh 3 months ago
codegen: local counter per repeated field on decode

Replaces `list[#list + 1] = val` with `_n_<fname> = _n_<fname> + 1;
list[_n_<fname>] = val` in every generated M.X_decode repeated-field
append site. One counter local per repeated non-map field, declared at
function entry. Counters survive across loop iterations so out-of-order
wire entries for the same field continue past the existing length
without re-scanning.

Profile attributed 6.2% of hello.Person 1KB decode to the `#list + 1`
re-traversal (26-email Person paid 26 list scans per decode).

Bench (Person full decode, msgs/s, median-of-3 vs post-4kj):
1KB +5.0%, 10KB +5.0%, 100KB +7.1%. Encode flat. Tests 745/745.
JIT 37/37, 0 bridges.

beads-tarantool-protobuf-cch
feecf8e0 — Eugene Blikh 3 months ago
codegen: inline 1-byte tag fast path at decode call sites

Hoists wire.decode_tag's 1-byte fast path into every generated
M.X_decode while-loop, falling back to the helper for multi-byte
tags (field ids > 15). The 1-byte case covers every protobuf field
with id 1..15 and is the dominant decode dispatch in real payloads.

Header now localizes string.byte, bit.band, and bit.rshift so the
inlined ops compile to straight local calls.

Bench (Person full decode, msgs/s, median-of-3 vs proper post-h8v
3-run baseline): 10B +14.7%, 100B +8.9%, 1KB +7.5%, 10KB +7.0%,
100KB +8.5%. Full encode is flat to small (-0.1% to -2.6%) at large
sizes, plausibly from header-upvalue layout. JIT trace gate: 37/37,
all bridges still 0. Tests: 745/745.

Also documented in bench/PERF_LOG.md, including the methodology
note that h8v's earlier numbers used single-run baselines and are
therefore ~3-5% optimistic; medians-of-3 are the standard now.

beads-tarantool-protobuf-4kj
9ee21c09 — Eugene Blikh 3 months ago
codegen: inline 1-byte varint length prefix at every LEN emit site

Eliminates the wire.encode_varint(#body) call + dispatch for every
length-delimited field in mode=full codegen. Profile flagged the
out[n] = wire.encode_varint(#_b) line as ~33% of hello.Person 1KB
encode time, with another ~17% in encode_varint dispatch — together
~50% of encode time. Lifting the 1-byte fast path (the dominant case
for proto strings and small message bodies) to the call site removes
the function frame entirely for lengths < 128.

Applied at every LEN emit site: singular/repeated message body,
singular/repeated string|bytes, packed scalar bundle, packed enum
bundle, map entry. Map value pieces (emitMapPiece message branch)
left as-is — they sit inside a single slot assignment that would
require a deeper restructure, and maps are not on the current hot
benchmark.

Results (hello.Person full encode, msgs/s): 10B +6.9%, 100B +7.9%,
1KB +25.7%, 10KB +48.1%, 100KB +31.9%. Decode flat (unchanged path).
Runtime mode flat (descriptor dispatch still calls encode_varint).
JIT trace gate: 37/37. Test suite: 745/745.

Bench history saved to bench/PERF_LOG.md with full numbers and the
workflow this iteration follows.

beads-tarantool-protobuf-h8v
2656c977 — Eugene Blikh 3 months ago
bench,codec: pin proto2 paths, kill pairs() on extension hot path

JIT trace gate gains 12 proto2-specific checks (required encode/decode,
groups singular + repeated, extension encode/decode). The extension-encode
check fired NYI on bytecode 72 (ISNEXT) — pairs() over the new
extensions_by_full_name hash is the same trace-abort that gates map
encode. Fix: register_extension now also appends to extensions_list,
an array view. codec.encode_message, text.emit_message and
json.encode_message all switch to ipairs over the list. Hash tables
stay around for O(1) lookups in decode (extensions_by_id) and bracket-
name resolution (extensions_by_full_name).

Inline (full-mode) codegen learns to walk extensions too: before this
commit the inline encoder skipped t._extensions entirely (only the
runtime codec walked it), so a generated _encode silently dropped any
extension data set on the message. Add the array-walk after the field
loop and a decode_extension dispatch in the unknown-tag branch — the
inline path now matches runtime byte-for-byte.

bench/bench.lua parameterizes over a FIXTURES list so the baseline can
cover both hello.Person and a new proto2_basic.BenchPayload fixture
(required + group + extension + repeated). baseline.json restructured
under "schemas": [{schema, results}, …]; compare walks both. Fresh
numbers committed.

740/740 luatest cases pass; JIT gate 37/37; conformance 2806 binary+JSON
and 434 text-format, both 0 failures.
5a1dc35b — Eugene Blikh 3 months ago
codec,text,json: proto2 extensions end-to-end

Plugin iterates file.Extensions and per-message Extensions, emitting
\`pb.register_extension(extendee_desc, {…})\` calls. Each extension
becomes a field descriptor attached to the extendee under two
indices: extensions_by_id (wire-decode lookup) and
extensions_by_full_name (encode + textual emission ordering).

Codec encode_message walks data._extensions after the regular field
loop and calls encode_field through the extension's descriptor.
decode_message routes an unknown tag through decode_extension when
extensions_by_id matches; the helper mirrors the in-line dispatch
on field kind (scalar/enum/message/group, singular/repeated) and
stores into result._extensions[full_name].

Text decoder recognizes bracket syntax \`[pkg.ext_name]\` outside an
Any-target and looks the name up in extensions_by_full_name. Names
that don't resolve (e.g. \`[pkg.GroupField]\` for the CapitalCase
group type instead of the lowercase field name) raise a parse error
per spec. Text encoder emits each set extension as
\`[full.name]: value\` or \`[full.name] { … }\`.

JSON encoder emits set extensions under the bracketed full-name key
(\`"[pkg.ext_name]": value\`). JSON decoder recognizes the same
shape and stores into _extensions; unknown bracket-names stay
silently dropped to match the spec's tolerant behavior for unknown
JSON keys.

Extensions on google.protobuf.* descriptors (file/message/field
option extends) are skipped — those are meta-only and our WKT
module doesn't surface their descriptors.

Conformance baseline (strict --enforce_recommended, protobuf v34.1):
  Binary + JSON suite: 2806 ✓ / 0 failures   (was 1493 ✓ / 1313 skipped)
  Text-format suite:    434 ✓ / 0 failures   (was  416 ✓ /   18 skipped)

100% pass.
e9b650e9 — Eugene Blikh 3 months ago
text,codec: proto2 group text syntax + closed-enum semantics

Text decoder now resolves a group field reference by the group's
capitalized submessage name (e.g. \`Data\`, \`MultiWordGroupField\`)
and by the ASCII-lowercase fold (\`data\`, \`multiwordgroupfield\`),
in addition to the existing lowercase field-name lookup. The \`:\`
between field and \`{\` is optional for groups (matches the
message/map rule).

Proto2 enums are closed: parse_enum_value now rejects an integer
literal that doesn't map to any declared value. The plugin emits
\`closed = true\` on every proto2 enum descriptor (driven by
protoreflect's IsClosed()); proto3 enums stay open to preserve
forward-compatibility on the wire.

Conformance text-format suite: 16 unexpected failures → 3, all in
the remaining extension-bracketed-group cases.
5fa0fd00 — Eugene Blikh 3 months ago
codec: proto2 groups (SGROUP/EGROUP wire format)

Plugin: detect protoreflect.GroupKind, emit kind='group' in the
field descriptor and a SGROUP opening tag in inline codegen. The
group body bypasses the LEN-prefix path entirely — encoder emits
start-tag, body bytes, end-tag in three slots; decoder calls
pb.codec.decode_group(desc, buf, pos, field_id) which reads inner
tags until the matching EGROUP id.

Wire layer already understood SGROUP/EGROUP for skip_field; the new
decode_group reuses the per-tag dispatch from decode_message but
stops on EGROUP instead of end-of-buffer. Repeated groups bracket
each element with its own SGROUP/EGROUP pair.

Runtime parser now desugars `optional|required|repeated group Name
= id { body }` into (a) a nested message named Name and (b) a
synthetic field of kind=group whose lowercased name is `name` — so
source-parsed proto2 schemas behave the same as build-time codegen.

Text format renders groups under the submessage's capitalized name
(`SingleGroup { ... }`) rather than the lowercase field name,
matching mainline protoc's convention.

Adds a vendored, MessageSet-stripped test_messages_proto2.proto in
test/conformance/proto/ (header comment documents the patch).
10 new luatest cases (group_*) cover singular + repeated + text +
descriptor kind, across both codegen modes. 739 tests pass.
4fbdb65d — Eugene Blikh 3 months ago
codegen: proto2 baseline — required, optional, custom defaults

Lifts the proto3-only syntax gate in the plugin and threads three
new field-descriptor attributes through codegen and the codec:

  * required=true   — fields declared with the proto2 `required` keyword.
                      Inline codegen and the runtime codec both error when
                      a required field is missing on encode (vs the silent
                      elide that proto3 implicit-presence fields get).
  * optional=true   — already wired for proto3 explicit `optional`; in
                      proto2 every singular field carries it via the
                      existing HasOptionalKeyword() check, giving presence
                      semantics without a separate emission path.
  * default_value=… — proto2 [default = X] from the field descriptor,
                      rendered as a Lua literal (cdata for 64-bit ints,
                      symbolic name for enums) so consumers can surface
                      it; the codec itself does not auto-materialize
                      defaults on decode, matching how proto3 absent
                      fields stay nil.

Packed-by-default already flips correctly because we ask
protoreflect's `IsPacked()`, which is syntax-aware.

Adds test/proto/proto2_basic.proto with 33 luatest cases covering
required validation, optional presence, custom defaults, the proto2
unpacked-by-default repeated rule, nested-required messages, and
full-vs-runtime mode parity. `just gen-proto2-tests` regenerates the
fixture into examples/expected/{full,runtime}/.

Out of scope: extensions, extend, group; conformance harness still
skips TestAllTypesProto2.
7676fdc2 — Eugene Blikh 3 months ago
codegen: preserve descriptor options as `options = { ... }`

Every populated *Options message — FileOptions, MessageOptions,
FieldOptions, OneofOptions, EnumOptions, EnumValueOptions,
ServiceOptions, MethodOptions — surfaces on the generated descriptor as
a plain Lua sub-table named `options` (or `oneof_options` /
`value_options` for the per-member shapes). Standard fields use their
proto name as a bare Lua key; extensions use their fully-qualified
extension name as a bracket-quoted string key.

The walker is generic — no extension-specific code paths. Consumers
pull whatever they care about: `(google.api.http)` for REST routing,
`(versionpb.etcd_version_*)` for compatibility gates, `[deprecated =
true]` for migration tooling, and any in-house extension without pb
knowing about them. Standard fields sort alphabetically before
extensions (also alphabetical by full name) so codegen output stays
byte-identical across runs.

The `options` key is only emitted when at least one field is populated,
so option-free protos produce zero-diff output to before. Resolver
re-links *Options* messages so in-file extensions surface via the
protoreflect walker — protogen builds f.Desc before in-file extensions
are registered, and only f.Proto gets the post-pass fix-up, so we
rebuild the resolver manually.

UninterpretedOption is treated as a codegen-time error: a populated
entry means protoc couldn't resolve the extension, and emitting
opaque parser state would hide the problem.
14e19819 — Eugene Blikh 3 months ago
codegen: bracket-quote Lua-keyword field names

The plugin emitted bare-identifier field names in three positions:
the `M.<Type>_fields` table key, the inline encoder's `v = t.<name>`
load, and the inline decoder's `result.<name> = ...` store. When a
proto field name collided with a Lua reserved word the generated
`*_pb.lua` failed to load with `'(' expected near '<keyword>'`.

The real-world hit is pprof's profile.proto, which declares
`repeated Function function = 5` — that breaks all three emit sites.

Route every user-named identifier through new luaTableKey /
luaFieldAccess helpers that bracket-quote reserved words. Covers
field_names + oneof descriptors, oneof presence pre-pass, inline
encode/decode field bodies (including repeated and map paths), and
optional has/clear accessors.
06b2978a — Eugene Blikh 3 months ago
codegen: resolve (tarantool.lua_package) via global type registry

The custom file option was being dropped silently: protoc encoded it
correctly into the FileDescriptorProto, but protobuf-go parked the
unknown extension in the message's unknown-fields tail because
E_LuaPackage was never registered with protoregistry.GlobalTypes. As a
result proto.GetExtension returned "" and every override the README
documented was a no-op — every caller fell through to the default
"<pkg>.<file>_pb" path resolution.

Register E_LuaPackage in init() and add a luatest regression that
asserts both the output path and the cross-file require strings honor
the option, parameterized over both codegen modes.
ab214a39 — Eugene Blikh 3 months ago
codegen: emit strict <Type>_fields / _oneofs constants for lazy view

Lazy-view callers passing a typo'd field name to :get / :has / :set /
:clear / :which got `nil` back, indistinguishable from a legitimately-
absent optional field. Failures surfaced as missing data downstream.

Each generated message now exports a M.<Type>_fields table mapping
each field name to itself (and M.<Type>_oneofs for oneof groups),
wrapped by a new pb.field_names() helper that errors on unknown-key
reads and on any write. Routing field-name arguments through these
tables turns a typo into a load-time error at the read site.

Eager _encode / _decode keep round-tripping plain Lua tables — the
constants table is a lazy-view contract, documented in
docs/api-modes.md. README and lazy_test.lua converted to the new
pattern; three new tests cover typo / read-only / oneof-typo errors.
428ee1f6 — Eugene Blikh 3 months ago
codegen: propagate proto comments into generated _pb.lua

Leading `//` comments on messages, enums, enum values, fields, services,
and RPC methods now surface in the generated Lua:

- Message / enum descriptions become `---` blocks above `---@class` /
  `---@alias`, so LuaLS shows them on hover.
- Per-field comments collapse onto a trailing `@ description` on the
  matching `---@field` line.
- Enum values, service banners, and per-method entries get plain `--`
  lines inside the table literals so readers without an LSP still see
  the proto-side context.

Covers both `mode=full` and `mode=runtime` (emission is mode-independent
but the new luatest group runs against both).
f5c5ee6c — Eugene Blikh 3 months ago
codec: preserve -0.0 for proto3 float/double scalars

Proto3 default-elision dropped any singular float/double whose value
compared equal to 0 — `-0.0 == 0.0` in IEEE so the `if v ~= 0` guard
silently elided negative zero. The wire bytes for -0 differ from +0
and the TextFormatInput conformance corpus pins that -0 must survive
a round-trip; the failure surfaced as 10 unexpected text-suite
regressions covering FloatFieldNegativeZero (3 spellings × 2 outputs)
and Neg{Float,Double}FieldLargeNegativeExponentParsesAsNegZero
(2 types × 2 outputs).

Sign-bit guard via `1/v == math.huge` (positive zero yields +inf,
negative zero yields -inf). Applied in three layers:
  * runtime/pb/codec.lua: is_default_scalar + the specialized
    monomorphic writer for non-optional numeric scalars
  * runtime/pb/text.lua: is_proto3_default (text encoder elision)
  * inline codegen: scalarNotDefaultExpr emits the guard for
    float/double fields in full-mode `_encode` functions

Proto3 text-format conformance now sits at 416 ✓ / 18 skipped / 0
expected failures; binary+JSON holds at 1478 ✓. Unit-test regressions
cover both directions (preserved on encode + decode round-trip, +0
still elided) and use a runtime-computed -0.0 sentinel because LuaJIT
can constant-fold the literal `-0.0` to a sign-less zero in some
load paths.
7ec8f2b4 — Eugene Blikh 3 months ago
text: add pb.text.decode and wire it into conformance dispatch

Hand-written recursive-descent parser for the textproto grammar
covering every bucket the proto3 conformance suite exercises:
decimal/hex/octal integer literals with full 32/64-bit range checks,
float specials (inf/infinity/nan any case, oversize exponents
saturating to ±inf, underflows to ±0), C-style + \u/\U string escapes
with adjacent-literal concat and surrogate rejection, aggregate {} /
<> bodies, repeated short-form `[a, b, c]`, `key: K value: V` map
entries, the `[type.googleapis.com/...]` inline Any form alongside
the direct `type_url:`/`value:` form, enum-by-name-or-number,
reserved-name silent drop, numeric-field-ID tolerance, and
duplicate-singular-field rejection.

Plugin gains a small reserved_names emitter so the parser can match
mainline TextFormat::Parser's "silently drop reserved" rule. The Any
WKT descriptor advertises its real fields (type_url + string,
value + bytes) so the generic body walker can populate it directly
when the input doesn't use the inline-URL form.

cmd/conformance/core.lua stops short-circuiting text_payload to
`skipped` and runs it through pb.text.decode. The proto3 TextFormat
input suite climbs from 8 ✓ / 426 skipped to 406 ✓ / 18 skipped / 10
expected failures. The 10 surviving failures all share one cause
(proto3 -0.0 elision in the codec, not a parser bug — documented in
test/conformance/known_failures_text.txt). Binary+JSON conformance
holds at 1478 ✓. 591 unit tests pass across both codegen modes.

Closes the text-conformance-output branch.
343e4ba4 — Eugene Blikh 3 months ago
text: render captured unknown fields, tolerate SGROUP in skip

Two changes close the proto3 text-format conformance suite:

  1. `wire.skip_field` learns SGROUP/EGROUP. Wire 3 recurses through
     inner tags until a matching EGROUP, with field_id checked against
     the SGROUP's id. Callers (codec.lua, lazy.lua, wkt.lua, generated
     full-mode `_pb.lua`) now pass the tag's field_id so groups inside
     unknown-field skips don't error.

  2. `pb.text.encode` walks the captured `_unknown_fields` buffer when
     `opts.print_unknown_fields=true` and emits each entry in
     TextFormat numeric-field form:
       VARINT  -> "<id>: <uint64>"
       I64/I32 -> "<id>: 0x<hex>"
       LEN     -> speculative "<id> { <recurse> }"; rolls back to
                  byte-string form if the inner bytes don't parse as a
                  sub-message
       SGROUP  -> "<id> { <recurse> }" through matching EGROUP

`cmd/conformance/core.lua` threads `req.print_unknown_fields` into
`pb.text.encode` so `_Drop` tests drop unknowns and `_Print` tests
render them.

Conformance: text-format suite goes from 2 ✓ / 6 expected fails to
8 ✓ / 0 expected fails. All eight regression tests in
`conformance_test.lua` (one per upstream test, plus the fixed field-1011
tag bytes that were miscomputed earlier) now assert the target output.
ac9b9c13 — Eugene Blikh 3 months ago
codegen+wire: split length-prefix emission + 2-byte varint fast path

Two complementary encode optimizations: codegen + runtime writers no
longer pay a per-field string concat for length-prefixed fields, and
encode_varint_slow now handles 2/3/4-byte values without dropping into
the uint64 cdata path.

Composite bench/bench.lua, full mode:
  1KB encode:    229 K -> 332 K msgs/s  (1.45x)
  10KB encode:   38 K  -> 56.5 K        (1.49x)
  100KB encode:  4.1 K -> 6.7 K         (1.64x)

Runtime mode now matches full mode at 10KB+:
  1KB encode:    203 K -> 276 K  (1.36x)
  10KB encode:   35 K  -> 55 K   (1.56x)

bench/shapes_bench.lua biggest swings (both modes):
  packed-int32x1000 enc:  1.7 K  -> 13 K  (7.0-7.6x)
  packed-int32x100  enc:  21 K   -> 113 K (5.3x)
  scalar-heavy      enc:  582 K  -> 1.0 M (1.7x)

Per-helper, bench/wire_bench.lua:
  encode_varint(150)  [2-byte]:   529 ns -> 68 ns  (7.8x)
  encode_varint(20K)  [3-byte]:   841 ns -> 88 ns  (9.6x)
  encode_tag(16, LEN) [2-byte]:   531 ns -> 78 ns  (6.8x)
  encode_string(200B) [2-byte L]: 560 ns -> 109 ns (5.1x)
  encode_varint(127)  [1-byte]:    29 ns -> 28 ns  (no regression)

1. Split length-prefix emission. Length-delimited fields (string/bytes
   scalars, nested messages, packed scalars/enums) used to emit
   `tag → encode_len(body)` where `encode_len(body)` returns
   `encode_varint(#body) .. body`. The string concat allocated a copy
   of the body per field. Now the codegen and runtime writers emit
   three separate `out` slots — `tag`, `varint(#body)`, `body` — and
   let `table.concat(out)` join them in one pass at the end of encode.

   Applied to inline.go (full-mode codegen) for: singular and repeated
   nested messages, singular and repeated string/bytes scalars, packed
   scalars, packed enums. Applied to codec.lua build_writer / build_
   repeated_writer for the same set. Maps still go through encode_len
   pending a separate pass.

2. encode_varint_slow Lua-number fast paths. The outer encode_varint
   stays at the tiny `1-byte check + tail call` shape that LuaJIT
   inlines into hot traces. The slow function (not inlined into hot
   traces, so its body size is unconstrained) now handles non-negative
   Lua numbers up to 2^28 directly via bit.rshift / string.char with no
   cdata allocation. Values in [2^28, 2^53) emit one byte and recurse
   on the smaller residue. Only cdata inputs, negative Lua numbers
   (sign-extended to 10-byte varint), and the rare > 2^53 case still
   take the uint64 cdata loop. Net effect: every multi-byte varint
   encode that fits in a Lua number — including the length prefix for
   any string >= 128 bytes, every tag for field IDs >= 16, and every
   negative-zigzag sint — drops from ~500 ns to ~70 ns.

497/497 luatest pass.  23/23 jit-trace gates pass (the two new
multi-byte varint gates added in the bench infra commit confirm
encode_varint_slow JIT-compiles cleanly).  Conformance suite (binary
+ text) shows 1478 expected passes, 0 unexpected failures.
96ed328e — Eugene Blikh 3 months ago
json: treat null fields as absent (and Value's null as a real value)

Per the proto3 JSON spec, a null on any field means "use the field's
default" — encoded as missing — with the lone exception of
google.protobuf.Value, where JSON null is itself a Value carrying
NullValue.NULL_VALUE.

Three coupled bugs surfaced together:

1. decode_field_value used to fall through with v = box.NULL, leaving a
   useless box.NULL sitting in the result table for scalars. Now it
   returns nil for non-Value fields, PB_NULL for Value fields.

2. decode_message's repeated and map branches called `#jv` and
   `pairs(jv)` unconditionally; a JSON-null on either type crashed with
   "attempt to get length of 'void *'". Now both branches short-circuit
   when jv is box.NULL.

3. The nil-skip checks in the decode loop (`if dv ~= nil`) and in the
   codec / inline message encoders (`if v == nil then return end`)
   evaluated TRUE on box.NULL because Tarantool's cdata __eq aliases
   it to nil. Decode now uses rawequal(dv, nil); encode special-cases
   message kind by also accepting cdata, so the Value field's
   box.NULL sentinel survives all the way through to value_encode.

Drops 3 entries from test/conformance/known_failures.txt
(AllFieldAcceptNull, WrapperTypesWithNullValue, ValueAcceptNull).
Adds 5 regression tests covering scalar / repeated / map / wrapper
null treatment and the Value-NULL_VALUE exception.
849b7662 — Eugene Blikh 3 months ago
codec: recursively merge repeated singular-message wire entries

Per proto3 spec, when the same singular message field (including a oneof
branch) appears twice on the wire, the two values must merge: scalar
fields last-wins, repeated fields concatenate, sub-messages merge
recursively, maps last-wins per key. The previous reader replaced the
prev value wholesale for oneof branches and overwrote repeated/nested
fields with `prev[k] = v` even outside oneofs, losing data unique to
the first occurrence.

Adds wire.codec.merge_message(desc, prev, decoded), a descriptor-driven
recursive merge, and routes both codec.lua's reader and the inline-mode
codegen through it. WKT message fields (custom decode) keep the replace
behavior because their decoded value is not a generic Lua table.

Exposes pb.codec to the generated inline code so the helper is reachable
without a per-call require.

Drops 3 entries from test/conformance/known_failures.txt:
ValidDataOneof.MESSAGE.Merge, ValidDataOneofBinary.MESSAGE.Merge,
RepeatedScalarMessageMerge. Adds 5 regression tests covering scalar
last-wins, oneof merge, recursive sub-message merge, repeated-in-
submessage concat, and oneof sibling clearing after merge.
0c13fd73 — Eugene Blikh 3 months ago
wire: truncate varints to 32 bits in int32/uint32/sint32/enum decode

decode_int32/uint32/sint32 returned full uint64 values when the wire input
carried bits above bit 31, corrupting re-encode on 51 conformance tests that
exercise overlong or over-range varints. Per the proto3 spec the decoder
must keep only the low 32 bits (and sign-extend for signed types).

Adds wire.varint_to_int32 / varint_to_uint32 and routes every enum-varint
decode site through them: wire.lua typed decoders, codec.lua (5 enum
sites), lazy.lua (3 sites), and the generated code via inline.go (3 sites).

Drops 51 entries from test/conformance/known_failures.txt.
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