Factor the lookup/planning half of the protocol emission functions into
protocols.zig, keeping IR emission in Lowering (PLAN-ARCH A4.2 final increment):
- protocolMethodInfos(proto) — the dispatch method table = which methods
getOrCreateThunks must thunk. getOrCreateThunks now does PLANNING via this +
EMISSION (createProtocolThunk loop) in Lowering.
- findVisibleImpls(entries, out) — moved verbatim (pure BFS over the import
graph; the cross-module visibility selection behind the 0410 path).
tryUserConversion calls it via the resolver.
- matchPackImpl(src_ty, pack_key) -> ?PackImplMatch — the pure pack-impl
matching loop (prefix + return match) + convert-method find, returning the
matched entry + convert fd + src params/ret. tryPackImplMatch consumes it; the
binding + monomorphise + call emission stays in Lowering.
Emission untouched: createProtocolThunk, buildProtocolValue, and the
monomorphise+call tails of tryUserConversion / tryPackImplMatch remain in
Lowering. The reentrancy guard, key-build, and the Into no-visible / duplicate /
recursive diagnostics stay in tryUserConversion (byte-for-byte). lower.zig net
-94 lines. No new pub exposure (uses the existing ParamImplEntry /
PackParamImplEntry / formatTypeName surface).
protocols.test.zig +3: protocolMethodInfos (method table + null-for-unknown, no
silent empty default); findVisibleImpls (falls open with no graph; filters to
here + transitive imports); matchPackImpl (selects on prefix+return; null for
non-closure source / unknown key).
zig build, zig build test, tests/run_examples.sh (357/0) all green — no .ir
churn; the 0410/0411/0412 diagnostics are byte-for-byte preserved.
Move the registration functions behind the protocols.zig facade, per PLAN-ARCH
A4.2 ("then registration", keeping IR emission in Lowering):
- registerProtocolDecl (protocol struct + dispatch method table + vtable type),
- registerImplBlock (concrete impl -> <Target>.<method> in fn_ast_map + default-
method synthesis),
- registerParamImpl (parameterised impl -> param_impl_map / param_impl_pack_map
+ the same-file duplicate diagnostic),
- synthesizeDefaultMethod (facade-private; its only caller moved too).
Moved verbatim with self. -> self.l. facade rewrites. Emission stays in
Lowering: the registry calls self.l.declareFunction (the extern-stub primitive)
but the thunk/value builders (createProtocolThunk / buildProtocolValue /
tryUserConversion / getOrCreateThunks) are NOT moved.
Lowering keeps registerProtocolDecl as a thin pub wrapper (scan pass + 7
unit-test callers); registerImplBlock / registerParamImpl /
synthesizeDefaultMethod deleted (no fallback), the 2 scan call sites routed
through protocolResolver(). New pub: declareFunction (8 callers, emission infra),
ParamImplEntry / PackParamImplEntry (the registry constructs them; stay as
Lowering nested types). State maps remain on Lowering; the facade reads/writes
self.l.* (migrate once planning lands).
protocols.test.zig +2: registerImplBlock records Circle.draw in fn_ast_map (and
packArgConformsTo then sees it); registerParamImpl flags a same-file duplicate
impl Into(s64) for IntCell (the 0412-class, unit level).
zig build, zig build test, tests/run_examples.sh (357/0) all green — no .ir
churn; the 0410/0411/0412 rejection diagnostics are byte-for-byte preserved.
Move the pure protocol/impl conformance lookups into one module,
src/ir/protocols.zig, behind a *Lowering facade (ProtocolResolver), mirroring
GenericResolver / CallResolver. Per PLAN-ARCH A4.2 ("move pure lookup first;
keep emission in Lowering"), this increment moves only the read-only queries:
- getProtocolInfo (is a type a registered protocol + its method table),
- hasImplPlain (have the (protocol, type) thunks been materialized),
- packArgConformsTo (impl-declaration-level conformance for ..xs: P).
Registration (registerProtocolDecl / registerImplBlock / registerParamImpl) and
all IR emission (createProtocolThunk / buildProtocolValue / tryUserConversion /
getOrCreateThunks) stay in Lowering for the later increments. The state maps
(protocol_thunk_map / param_impl_map on Lowering, protocol_decl_map /
protocol_ast_map in ProgramIndex) stay put; the facade reads them via self.l.* —
no map migration.
Lowering keeps getProtocolInfo as a thin pub wrapper (~9 callers incl.
calls.zig); hasImplPlain + packArgConformsTo are deleted (no fallback), their 3
call sites (computeHasImpl x2, the pack-conformance check x1) routed through
self.protocolResolver(). formatTypeName widened to pub (the lookups use it);
protocolResolver() accessor added.
protocols.test.zig (wired into the barrel) drives ProtocolResolver directly:
getProtocolInfo (registered vs builtin/plain-struct + wrapper delegation),
hasImplPlain (thunk-map materialization), packArgConformsTo (non-parameterised
requires <ty>.<m> in fn_ast_map; trivially-true for an erased protocol value;
false for unknown protocol).
zig build, zig build test, tests/run_examples.sh (357/0) all green — no .ir
snapshot churn; the 0410/0411/0412 rejection anchors still pass.
