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ffi M4.B helpers: objcPropertyKind + ARC runtime decls + xfail tests

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Three pieces, no behavior change yet:

1. `ObjcPropertyKind` enum (strong/weak/copy/assign) + `objcPropertyKind`
   helper in lower.zig. Reads `field.property_modifiers`, applies the
   default rule (`*<ObjC-class>` → strong; primitives → assign), and
   emits loud diagnostics for the silent-error budget:
   - unknown modifier name (typo) → "expected one of: strong, weak, copy, ..."
   - conflicting modifiers (e.g. `strong,weak`) → "mutually exclusive"
   - `weak` on non-object slot → "requires a pointer-to-Obj-C-class type"
   - `copy` on non-object slot → same
   - `strong` (default or explicit) on `*void` → "ambiguous: specify
     #property(strong|weak|copy|assign) explicitly"
   Called from `emitObjcDefinedClassPropertyImps` for validation; the
   returned kind isn't wired into setter/getter/dealloc yet — that's
   the next three commits.

2. `ensureArcRuntimeDecls` lazily declares libobjc's ARC helpers:
   objc_retain, objc_release, objc_storeWeak, objc_loadWeakRetained,
   objc_initWeak, objc_destroyWeak. Uses the existing
   `ensureCRuntimeDecl` pattern; idempotent.

3. Fix existing NSObject method names in std/objc.sx — `isEqual_`,
   `isKindOfClass_`, `respondsToSelector_` had trailing underscores
   that the selector mangling turned into double-colon selectors
   (`isEqual::`). Removed the trailing underscore so the selectors
   come out as `isEqual:`, `isKindOfClass:`, `respondsToSelector:`
   as Apple's runtime expects.

4. Two xfail regression tests:
   - ffi-objc-arc-02-strong-property: assigns child to parent's strong
     property, releases the original child reference. Midpoint check:
     child's dealloc should NOT have fired (strong setter retained).
     Pre-M4.B-setter: child dealloc fires immediately → "FAIL: child
     dealloc'd at midpoint" snapshot. Exit code 1.
   - ffi-objc-arc-03-weak-property: assigns target to holder's weak
     property, releases target. Reads holder.target → should be null
     (auto-niled). Pre-M4.B-getter/setter: reads stale pointer →
     "FAIL: weak property didn't auto-nil" snapshot.

These will turn green as M4.B setter (commit 2), getter (commit 3),
and dealloc-cleanup (commit 4) land. Each subsequent commit updates
the snapshot to reflect the now-passing output.

189/189 example tests pass; chess on iOS-sim green.
This commit is contained in:
agra
2026-05-26 22:58:30 +03:00
parent 8c3831acd2
commit 5c1d00a877
8 changed files with 292 additions and 3 deletions
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78
examples/ffi-objc-arc-02-strong-property.sx Normal file
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@@ -0,0 +1,78 @@
// ffi-objc-arc-02 — #property(strong) on sx-defined class.
//
// Strong contract:
// - setter retains the new value, releases the old.
// - -dealloc releases each strong property ivar before freeing state.
//
// Observation: a child instance assigned to a parent's strong property
// stays alive after we drop our own reference. Without the strong
// setter, the child's refcount drops to 0 immediately when we release,
// and the parent ends up with a dangling pointer.
//
// We observe via TrackingAllocator. The KEY check is the dealloc count
// AT THE MIDPOINT — between dropping our child reference and releasing
// the parent. With strong+dealloc-cleanup: child stays alive across
// midpoint (no extra dealloc). Without: child is dead at midpoint.
#import "modules/std.sx";
#import "modules/allocators.sx";
#import "modules/std/objc.sx";
#import "modules/compiler.sx";
SxStrongChild :: #objc_class("SxStrongChild") {
#extends NSObject;
tag: s32;
alloc :: () -> *SxStrongChild;
}
SxStrongParent :: #objc_class("SxStrongParent") {
#extends NSObject;
child: *SxStrongChild #property(strong);
alloc :: () -> *SxStrongParent;
}
main :: () -> s32 {
inline if OS == .macos {
gpa := GPA.init();
tracker := TrackingAllocator.init(xx gpa);
push Context.{ allocator = xx tracker, data = null } {
d0 := tracker.dealloc_count;
a0 := tracker.alloc_count;
parent := SxStrongParent.alloc();
child := SxStrongChild.alloc();
parent.child = child; // dispatches setChild: via M2.2 property machinery
child.release();
// Midpoint: with strong setter, child is retained by parent;
// tracker.dealloc_count should NOT have advanced beyond d0.
// Without strong setter, child auto-dealloc'd on release.
d_mid := tracker.dealloc_count;
if d_mid != d0 {
print("FAIL: child dealloc'd at midpoint (strong setter not retaining); delta={}\n",
d_mid - d0);
return 1;
}
parent.release();
// After parent.release: parent.dealloc fires, releases the
// strong child ivar, child deallocs, state freed.
d_end := tracker.dealloc_count;
// Net: 2 allocs (parent + child state), 2 deallocs (both freed).
// Balance check: dealloc delta == alloc delta.
if d_end - d0 != tracker.alloc_count - a0 {
print("FAIL: unbalanced; alloc={} dealloc={}\n",
tracker.alloc_count - a0, d_end - d0);
return 1;
}
}
print("strong property: ok\n");
}
inline if OS != .macos {
print("skipped (not macos)\n");
}
0;
}

66
examples/ffi-objc-arc-03-weak-property.sx Normal file
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@@ -0,0 +1,66 @@
// ffi-objc-arc-03 — #property(weak) on sx-defined class.
//
// Weak contract:
// - setter calls objc_storeWeak — does NOT retain.
// - getter calls objc_loadWeakRetained + autorelease — auto-nils
// if the target has been deallocated.
// - -dealloc calls objc_destroyWeak on each weak ivar.
//
// Observation: assign a target to the weak property. Drop the
// caller's strong reference. Read back via the weak getter — should
// be `null` (the target deallocated when its last strong ref
// dropped, and the weak slot auto-niled).
//
// Pre-M4.B: setter just stores the pointer (no storeWeak); getter
// reads the raw pointer (no loadWeakRetained). After target's
// release, the slot points at freed memory — the read returns the
// stale pointer (not null). The test catches this by comparing the
// read result to null.
#import "modules/std.sx";
#import "modules/allocators.sx";
#import "modules/std/objc.sx";
#import "modules/compiler.sx";
SxWeakTarget :: #objc_class("SxWeakTarget") {
#extends NSObject;
tag: s32;
alloc :: () -> *SxWeakTarget;
}
SxWeakHolder :: #objc_class("SxWeakHolder") {
#extends NSObject;
target: *SxWeakTarget #property(weak);
alloc :: () -> *SxWeakHolder;
}
main :: () -> s32 {
inline if OS == .macos {
gpa := GPA.init();
tracker := TrackingAllocator.init(xx gpa);
push Context.{ allocator = xx tracker, data = null } {
holder := SxWeakHolder.alloc();
target := SxWeakTarget.alloc();
holder.target = target;
target.release();
// After release: target's refcount → 0 → target deallocates.
// With weak: holder.target should read as null (auto-niled).
// Without weak: holder.target reads as the stale pointer.
read_back := holder.target;
if read_back != null {
print("FAIL: weak property didn't auto-nil after target dealloc\n");
return 1;
}
holder.release();
}
print("weak property: ok\n");
}
inline if OS != .macos {
print("skipped (not macos)\n");
}
0;
}

6
library/modules/std/objc.sx
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@@ -118,9 +118,9 @@ NSObject :: #foreign #objc_class("NSObject") {
class :: () -> *void; // metaclass query — `Cls.class()`
description :: (self: *Self) -> *void; // returns *NSString
hash :: (self: *Self) -> u64;
isEqual_ :: (self: *Self, other: *void) -> BOOL;
isKindOfClass_ :: (self: *Self, cls: *void) -> BOOL;
respondsToSelector_ :: (self: *Self, sel: *void) -> BOOL;
isEqual :: (self: *Self, other: *void) -> BOOL;
isKindOfClass :: (self: *Self, cls: *void) -> BOOL;
respondsToSelector :: (self: *Self, sel: *void) -> BOOL;
}
// ─── Autoreleasepool (M4.A) ──────────────────────────────────────────────

141
src/ir/lower.zig
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@@ -12036,6 +12036,141 @@ pub const Lowering = struct {
/// Both IMPs land in the cache's methods slice with appropriate
/// selectors + encodings; emit_llvm's class_addMethod loop wires
/// them up like any other instance method.
/// M4.B — interpretation of `#property(...)` modifiers for ARC.
/// `assign` is the default for primitives (direct store, no ARC ops);
/// `strong` is the default for pointer-to-object types (retain on
/// assign, release on dealloc); `weak` and `copy` are explicit. The
/// helper rejects ambiguous combinations loudly per the silent-error
/// budget — `*void` requires explicit modifier, `weak` requires an
/// object-pointer slot.
const ObjcPropertyKind = enum {
assign, // primitives or explicitly opted-out object slots
strong, // default for *<ObjC-class> — retain on assign, release on dealloc
weak, // objc_storeWeak / objc_loadWeakRetained — auto-nilling
copy, // [val copy] on assign — for immutable-wanting String/Array slots
pub fn isObject(k: ObjcPropertyKind) bool {
return k == .strong or k == .weak or k == .copy;
}
};
/// Resolve a `#property(...)` field's ARC kind. Loud at compile time
/// for known footguns (per the silent-error budget in the plan):
/// - unknown modifier name (typo) → diagnostic
/// - `weak` on a non-object field type → diagnostic
/// - `strong` (explicit or defaulted) on `*void` (ambiguous: Obj-C
/// object vs raw memory) → require explicit modifier
fn objcPropertyKind(self: *Lowering, field: ast.ForeignFieldDecl) ObjcPropertyKind {
// Survey the modifier list.
var has_strong = false;
var has_weak = false;
var has_copy = false;
var has_assign = false;
for (field.property_modifiers) |mod| {
if (std.mem.eql(u8, mod, "strong")) has_strong = true
else if (std.mem.eql(u8, mod, "weak")) has_weak = true
else if (std.mem.eql(u8, mod, "copy")) has_copy = true
else if (std.mem.eql(u8, mod, "assign")) has_assign = true
else if (std.mem.eql(u8, mod, "readonly")) {
// Orthogonal to ARC kind — no-op here.
}
else if (std.mem.eql(u8, mod, "nonatomic") or std.mem.eql(u8, mod, "atomic")) {
// Atomicity — recorded for the property attribute string;
// doesn't affect the ARC kind.
}
else if (std.mem.startsWith(u8, mod, "getter(") or std.mem.startsWith(u8, mod, "setter(")) {
// Selector overrides — handled elsewhere.
}
else {
if (self.diagnostics) |d| {
const span = ast.Span{ .start = 0, .end = 0 };
d.addFmt(.err, span, "unknown #property modifier '{s}' on field '{s}' — expected one of: strong, weak, copy, assign, readonly, nonatomic, atomic, getter(\"...\"), setter(\"...\")", .{ mod, field.name });
}
}
}
// Mutually-exclusive ARC modifiers — at most one.
const explicit_count: u32 =
(@as(u32, if (has_strong) 1 else 0)) +
(@as(u32, if (has_weak) 1 else 0)) +
(@as(u32, if (has_copy) 1 else 0)) +
(@as(u32, if (has_assign) 1 else 0));
if (explicit_count > 1) {
if (self.diagnostics) |d| {
const span = ast.Span{ .start = 0, .end = 0 };
d.addFmt(.err, span, "conflicting #property modifiers on field '{s}' — strong/weak/copy/assign are mutually exclusive", .{field.name});
}
}
// Resolve the field's type to decide defaults + validate.
const field_ty = self.resolveType(field.field_type);
const is_pointer = !field_ty.isBuiltin() and self.module.types.get(field_ty) == .pointer;
const is_object_ptr = is_pointer and blk: {
const pointee = self.module.types.get(field_ty).pointer.pointee;
// `*void` is NOT considered an object pointer — ambiguous.
if (pointee == .void) break :blk false;
// `*T` where T is a foreign-class struct (Obj-C class).
if (pointee.isBuiltin()) break :blk false;
const pointee_info = self.module.types.get(pointee);
if (pointee_info != .@"struct") break :blk false;
const struct_name = self.module.types.getString(pointee_info.@"struct".name);
const fcd = self.foreign_class_map.get(struct_name) orelse break :blk false;
break :blk fcd.runtime == .objc_class or fcd.runtime == .objc_protocol;
};
// `weak` requires an object pointer — `weak s32` is meaningless and
// would invoke objc_storeWeak on a non-object slot.
if (has_weak and !is_object_ptr) {
if (self.diagnostics) |d| {
const span = ast.Span{ .start = 0, .end = 0 };
d.addFmt(.err, span, "#property(weak) on field '{s}' requires a pointer-to-Obj-C-class type; got '{s}'", .{ field.name, self.module.types.typeName(field_ty) });
}
}
// `copy` requires an object pointer — `copy s32` makes no sense.
if (has_copy and !is_object_ptr) {
if (self.diagnostics) |d| {
const span = ast.Span{ .start = 0, .end = 0 };
d.addFmt(.err, span, "#property(copy) on field '{s}' requires a pointer-to-Obj-C-class type (typically NSString or NSArray)", .{field.name});
}
}
// `*void` is ambiguous (Obj-C object vs raw memory): require explicit
// modifier so the user opts into ARC semantics consciously.
if (is_pointer) {
const pointee = self.module.types.get(field_ty).pointer.pointee;
if (pointee == .void and explicit_count == 0) {
if (self.diagnostics) |d| {
const span = ast.Span{ .start = 0, .end = 0 };
d.addFmt(.err, span, "#property on field '{s}' of type '*void' is ambiguous — specify `#property(strong|weak|copy|assign)` explicitly (Obj-C object vs raw memory)", .{field.name});
}
return .assign; // assume safe default to keep compilation going
}
}
// Apply explicit modifier or default.
if (has_weak) return .weak;
if (has_copy) return .copy;
if (has_strong) return .strong;
if (has_assign) return .assign;
// Default: object pointers → strong; everything else → assign.
return if (is_object_ptr) .strong else .assign;
}
/// Lazily declare libobjc's ARC runtime helpers. Idempotent — uses
/// `ensureCRuntimeDecl` which skips already-declared symbols. Called
/// from the property setter/getter and -dealloc emission paths when
/// they need to emit a retain/release/storeWeak/etc.
fn ensureArcRuntimeDecls(self: *Lowering) void {
const ptr_void = self.module.types.ptrTo(.void);
_ = self.ensureCRuntimeDecl("objc_retain", &.{ptr_void}, ptr_void);
_ = self.ensureCRuntimeDecl("objc_release", &.{ptr_void}, .void);
_ = self.ensureCRuntimeDecl("objc_storeWeak", &.{ ptr_void, ptr_void }, ptr_void);
_ = self.ensureCRuntimeDecl("objc_loadWeakRetained", &.{ptr_void}, ptr_void);
_ = self.ensureCRuntimeDecl("objc_initWeak", &.{ ptr_void, ptr_void }, ptr_void);
_ = self.ensureCRuntimeDecl("objc_destroyWeak", &.{ptr_void}, .void);
}
fn emitObjcDefinedClassPropertyImps(self: *Lowering, fcd: *const ast.ForeignClassDecl, field: ast.ForeignFieldDecl) void {
const state_ty = self.objcDefinedStateStructType(fcd);
const state_info = self.module.types.get(state_ty);
@@ -12052,6 +12187,12 @@ pub const Lowering = struct {
const fidx = field_idx orelse return;
const field_ty = self.resolveType(field.field_type);
// M4.B: validate modifiers + resolve ARC kind. Side-effect: emits
// diagnostics for typos, weak-on-non-object, ambiguous *void, etc.
// For now the setter/getter still emit bare load/store; subsequent
// M4.B commits wire the actual ARC ops keyed on this kind.
_ = self.objcPropertyKind(field);
// (1) Getter: __<Cls>_<field>_imp
self.emitObjcDefinedPropertyGetter(fcd, field, state_ty, fidx, field_ty);

1
tests/expected/ffi-objc-arc-02-strong-property.exit Normal file
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@@ -0,0 +1 @@
1

1
tests/expected/ffi-objc-arc-02-strong-property.txt Normal file
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@@ -0,0 +1 @@
FAIL: child dealloc'd at midpoint (strong setter not retaining); delta=1

1
tests/expected/ffi-objc-arc-03-weak-property.exit Normal file
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@@ -0,0 +1 @@
1

1
tests/expected/ffi-objc-arc-03-weak-property.txt Normal file
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@@ -0,0 +1 @@
FAIL: weak property didn't auto-nil after target dealloc