Filed `issues/0045-pack-fn-call-llvm-verifier-failure.md`.
Surfaced by probing step 2 territory of the variadic
heterogeneous type packs feature: any `..$args` fn whose body
is a block containing `return X;` (or any comptime fn with a
non-void return, comptime params, and explicit `return` in a
block body) trips LLVM's "Terminator found in the middle of a
basic block" verifier.
`lowerComptimeCall` inlines the body's statements directly into
the caller's LLVM function. `lowerReturn` then emits a `ret`
into the caller's basic block — but the caller still has
trailing instructions, hence the verifier failure.
`examples/issue-0045.sx` reproduces the crash with the minimum
pack-fn shape (`foo :: (..$args) -> s64 { return 42; }`). Same
shape with a plain comptime param (`($x: s32) -> s64 { return
42; }`) reproduces identically, so the bug is broader than
packs. Arrow-form bodies (`=> 42`) work today because they have
no `return` statement.
Next commit teaches `lowerComptimeCall` to allocate a result
slot when the body contains a `return`, and reroutes
`lowerReturn` to store into that slot + flag the block as
terminated so the inliner picks up the value.
For UFCS dispatch on foreign-class receivers (`#foreign #objc_class`
aliases), `resolveCallParamTypes` was returning an empty slice — both
`resolveFuncByName(qualified)` and `fn_ast_map.get(qualified)` miss
for `#foreign` methods (they live in `foreign_class_map`, not the
regular fn maps). With `param_types` empty, the per-arg `target_type`
assignment in `lowerCall` was skipped, leaving `self.target_type` as
whatever it held on entry — usually the enclosing function's return
type. Inside a `-> BOOL` method, `xx ptr` then lowered with target
type `i8`: `ptrtoint ptr to i64` → `trunc i64 to i8`, sending the low
byte of the pointer through.
Symptom: chess on iOS-sim crashed in
`-[NSNotificationCenter addObserver:selector:name:object:]` with
`observer = 0xC0` (low byte of the SxAppDelegate receiver) when the
AppDelegate method's first param was renamed to anything other than
`self`. The original session diagnosed it as a `self`-vs-`this`
hardcoding in `lower.zig`, but those hardcoded `"self"` strings are
all on compiler-synthesized parameters (init scopes, JNI stubs,
property IMPs, dealloc IMPs) — not the user-facing #objc_class body
params. The bug was in arg-type resolution.
Fix walks `foreign_class_map` + `findForeignMethodInChain` to recover
the declared param types (skipping the implicit `*Self` for instance
methods). Regression test `examples/issue-0044.sx` exercises the
BOOL-return + foreign-class arg shape; pre-fix the receiver round-trip
prints WRONG, post-fix it prints ok.
Per CLAUDE.md IMPASSIBLE RULES. Attempted Phase 3.2 C4 migration of
the UIKit chrome cluster in `library/modules/platform/uikit.sx`
(UIScreen / UIWindow / UIViewController / UITextField / UIView)
surfaced a real compiler bug: when a function body contains
`recv.method(...)` calls against an `#objc_class` receiver AND that
body is reached via `lazyLowerFunction` invoked from another
`inline if OS == ...` branch, the method dispatch fails with
"unresolved 'methodName'".
Specifically: `uikit_scene_will_connect_ios` (the iOS-sim crashing
case) contains `UIWindow.alloc().initWithWindowScene(scene)` etc.
The same calls compile cleanly in isolated probes — only the lazy-
lower-via-inline-if entry chain reproduces the bug. macOS target
builds fine throughout; ios-sim trips it.
C1/C2/C3 (commits 1ea9cda / 17775b2 / 2a7c8e0) happen to land cleanly
because the methods they migrate are reached eagerly (or are niladic
so the dispatch path doesn't hit the failing branch). C4 + C5 stay
blocked pending issue-0043's fix in a separate session.
Issue filed at `issues/0043-lazy-lower-loses-foreign-class-method-dispatch.md`
with the reproduction, stack trace, and investigation prompt
pointing at `lower.zig:1057` (`lazyLowerFunction`) and
`lower.zig:5290` (the field-access foreign-class dispatch chain).
FFI checkpoint updated to mark C4+C5 as BLOCKED on 0043.
The in-progress C4 working-tree changes were reverted; tree is at
the C3 commit `2a7c8e0` and chess on macOS/iOS-sim/Android builds
cleanly.
The session-long set of changes that lay the groundwork for the
Jai-literal implicit-Context-parameter refactor. Lots of accumulated
work; the new arrival is the implicit-ctx foundation (steps 1+2 of
the plan in current/CHECKPOINT-MEM.md):
Step 1 — `CAllocator :: struct {}` stateless allocator in
library/modules/allocators.sx, delegating directly to
libc_malloc/libc_free. `ConstantValue` in src/ir/inst.zig gains a
`func_ref: FuncId` leaf so nested aggregates can carry function
pointers (the inline Allocator value's fn-ptr fields). Switch
sites updated in emit_llvm.zig, print.zig, interp.zig.
Step 2 — `emitDefaultContextGlobal` in src/ir/lower.zig synthesises
a static `__sx_default_context` global with a nested-aggregate
init_val pointing at the CAllocator → Allocator thunks. The
second-pass `initVtableGlobals` in emit_llvm.zig is generalised
to handle `.aggregate` init_vals (re-emits after func_map is
populated so func_ref leaves resolve to real symbols).
Also folded in from earlier work this session:
- Phase 1.1: `xx value` heap-copy in `buildProtocolValue` routes
through `context.allocator` via the new `allocViaContext` helper.
- interp.zig: `marshalForeignArg` double-offset bug fixed —
`heapSlice` already adds `hp.offset` to the slice ptr, so the
extra `+ hp.offset` was scribbling memcpy/memset into adjacent
heap state, corrupting `heap.items[0]`. Symptom: `build_format`
at comptime produced zero bytes, all `print` calls failed.
- Lazy lowering: `lazyLowerFunction` now declares foreign-body
functions as extern stubs in the local (comptime) module so
cross-module foreign calls resolve.
- Allocator API: all stdlib allocators on one-line `init() -> *T`
(CAllocator/GPA: libc-backed; Arena/TrackingAllocator: parent-
backed; BufAlloc: embeds state at head of user buffer).
- issues 0038 (transitive #import), 0039 (chess + stdlib migration
fallout), 0040 (generic struct method dot-dispatch), 0041
(pointer types as type-arg), 0042 (alias name resolution) — all
fixed; regression tests in examples/.
- Diagnostic: `emitError` now embeds the lowering's
`current_source_file` and enclosing function in the literal
message; SX_TRACE_UNRESOLVED=1 dumps a Zig stack trace at the
emit site so misattributed spans can't hide where the failure
is.
- tools/verify-step.sh (all-platforms gate) and tools/scratch.sh
(interp/codegen parity tester) added.
Test suite: 152 example tests pass; chess builds + screenshots on
macOS / iOS sim / Android.
