Codex corrective step before the A2 merge gate: A2.3 left type_bridge with a
parallel structural type-resolution algorithm and an inline tuple-literal-spread
shape in lower.zig with a `.void` fallback.
Finding 1 — single owner for structural shapes:
- TypeResolver.resolveCompound is now the sole structural type-shape
constructor. Namespaced on `table` (so the stateless type_bridge can call it)
and extended to own function types, plain `Closure(P...) -> R`, and plain
positional/named tuples (it already owned *T/[*]T/[]T/?T/[N]T). It returns
null only for the pack-shaped forms that need caller state (`Closure(..p)`,
spread tuples); OOM yields `.unresolved`.
- type_bridge: deleted its 8 independent structural resolvers
(resolveArray/Slice/Pointer/ManyPointer/Optional/Function/Closure/TupleType).
resolveAstType delegates those node kinds to resolveCompound via a binding-free
StatelessInner adapter. The only residual stateless shape code is two tiny
fallbacks for the pack-shaped forms resolveCompound defers
(resolveClosurePackShape — used by Into(Block) at registration time —
and resolveTupleSpreadShape) plus resolveParameterizedType (kept:
generic-instantiation convergence is A4.1 per PLAN-ARCH).
- lower.zig: stateful resolveTypeWithBindings uses resolveCompound; the
`.function_type_expr` switch arm is gone. PackResolver.resolveFunctionTypeWithBindings
deleted (subsumed). Plain closures/tuples now resolve via resolveCompound in
both paths; only pack closures / spread tuples reach PackResolver.
Finding 2 — no `.void` failure fallback in lower.zig pack handling:
- the inline tuple_literal-with-spread type assembly moved into
PackResolver.resolveTupleLiteralType (returns ?TypeId; OOM `catch return .void`
became `catch return .unresolved`).
Alias result preserved: TypeTable.aliases stays gone; no table.aliases reads;
ProgramIndex.type_alias_map threaded explicitly.
type_resolver.test.zig: resolveCompound test rewritten (namespaced + new
function/closure/tuple/pack-shape arms, arena-backed). Gate green: zig build,
zig build test, run_examples 350/0.
A2-merge gate: both parts in one commit, behavior-preserving (350/0).
Part 1 — retire the TypeTable.aliases borrow (build-enforced):
- type_bridge.zig: add `AliasMap` and thread it as an explicit param through
every name-resolving fn (resolveAstType, bridgeType, resolveTypeName, the
compound resolvers, resolveTupleLiteralAsType, resolveParameterizedType, the
inline enum/struct/union + error resolvers). resolveTypeName now forwards the
threaded map to TypeResolver.resolveNamed instead of reading table.aliases.
- lower.zig: all 31 resolveAstType callers pass
&self.program_index.type_alias_map; drop the lowerRoot loan.
- types.zig: remove the now-unused TypeTable.aliases field.
- type_bridge.test.zig: alias test passes alias_map explicitly; other calls
pass null.
Part 2 — pack projections get one owner + no .void failure sentinel:
- New packs.zig (PackResolver, a *Lowering facade): moves
resolveClosure/Tuple/FunctionTypeWithBindings, packTypeElems, packTypeArgs,
elementProtocolTypeArg out of Lowering. Call sites route through
Lowering.packResolver(); barrel-wired in ir.zig.
- The missing-projection `orelse .void` in packTypeArgs now emits a diagnostic
and fills the slot with .unresolved (the tripwire sentinel), never a real
.void; OOM `catch return .void` in the moved fns became .unresolved too.
Legitimate no-return-type `else .void` defaults are preserved.
- packs.test.zig: packTypeArgs bound/unbound/no-constraint/no-state cases +
the missing-projection backstop (diagnostic + .unresolved slot).
