Files
sx/examples/1312-ffi-objc-class-method-dispatch.sx
agra bdd0e96d78 feat(lang): block value requires no trailing ; (Rust-style)
A block's value is now its last statement ONLY when that statement is a
trailing expression with no `;`. A trailing `;` discards the value,
leaving the block void. This makes value-vs-statement explicit and lets
the compiler reject "this block was supposed to produce a value".

Compiler:
- Parser records `Block.produces_value` (last stmt is a no-`;` trailing
  expression) + `Block.discarded_semi` (the `;` that discarded a value),
  via `expectSemicolonAfter`. A trailing expression before `}` may now
  omit its `;` (previously a parse error). Match-arm and else-arm bodies
  are built value-producing regardless of the arm `;` (arms are exempt —
  the `;` is an arm terminator).
- Lowering: `lowerBlockValue` / the block-expr path / `inferExprType`
  respect `produces_value`. A value-position block that discards its value
  is a hard error (`lowerValueBody` for function bodies; the value-context
  `.block` path for if/else branches, `catch` bodies, value bindings,
  match arms). Pure-failable `-> !` bodies (value rides the error channel)
  and a value-if whose branches are void are handled without false errors.
- `defer`/`onfail` cleanup bodies lower as statements (void), so a
  trailing `;` there is fine.

Migration (behavior-preserving — output unchanged):
- stdlib + ~210 examples: dropped the trailing `;` on value-position last
  expressions. `format` now ends with an explicit `#insert "return
  result;"` (it relied on `#insert`-as-block-value, which `;` discards).
- Two `main :: () -> s32` examples that relied on the old silent
  default-return got an explicit trailing `0`.
- Rejection snapshots 0412 / 1013 regenerated (their quoted source lines
  lost a `;`); the diagnostics themselves are unchanged.

Docs/tests: specs.md "Block values" section; examples 0040 (rules) + 0041
(rejection); 3 parser unit tests. Filed issue 0066 (pre-existing
match-arm negated-literal phi-width quirk, surfaced not caused here).

Gates: zig build, zig build test, run_examples.sh -> 343 passed,
cross_compile.sh -> 7 passed (also refreshed its stale example names).
2026-06-02 09:23:50 +03:00

52 lines
1.7 KiB
Plaintext

// M1.2 A.4b.iii — instance-method dispatch through the Obj-C
// runtime. Each instance method now gets a C-ABI IMP trampoline
// registered via 'class_addMethod' at class-pair init time. The
// runtime can dispatch 'objc_msgSend(obj, sel)' to the
// trampoline, which reads the '__sx_state' ivar to find the
// state struct and forwards to the sx body.
//
// End-to-end (verifies registration only — sx-side
// 'obj.bump()' calls still bail at the M1.2 A.7 dispatch gate
// until +alloc/-dealloc (A.5/A.6) land too):
// 1. class_getMethodImplementation(SxFoo, sel_registerName("bump"))
// returns a non-null IMP — proves the trampoline is wired.
#import "modules/std.sx";
#import "modules/compiler.sx";
#import "modules/std/objc.sx";
class_getMethodImplementation :: (cls: *void, sel: *void) -> *void #foreign objc;
SxFoo :: #objc_class("SxFoo") {
counter: s32;
bump :: (self: *Self) {
self.counter += 1;
}
add :: (self: *Self, n: s32) {
self.counter += n;
}
}
main :: () -> s32 {
inline if OS == .macos {
cls : Class = objc_getClass("SxFoo".ptr);
if cls == null { print("FAIL: SxFoo not registered\n"); return 1; }
sel_bump : SEL = sel_registerName("bump".ptr);
imp_bump : *void = class_getMethodImplementation(cls, sel_bump);
if imp_bump == null { print("FAIL: bump IMP missing\n"); return 1; }
sel_add : SEL = sel_registerName("add:".ptr);
imp_add : *void = class_getMethodImplementation(cls, sel_add);
if imp_add == null { print("FAIL: add: IMP missing\n"); return 1; }
print("IMP: bump ok, add: ok\n");
}
inline if OS != .macos {
print("IMP: bump ok, add: ok\n");
}
0
}