bdd0e96d78
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).
68 lines
2.3 KiB
Plaintext
68 lines
2.3 KiB
Plaintext
// M2.2 (first pass) — `#property` directive on foreign-class
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// fields synthesizes Obj-C-runtime getter/setter dispatch.
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//
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// field: T #property[(modifiers)];
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//
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// `obj.field` → [obj field] (selector = field name)
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// `obj.field = x` → [obj setField:x] (selector = "set<Field>:")
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//
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// Selector mangling for the setter capitalises the first letter
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// of the field name. Modifiers (strong, weak, copy, readonly, ...)
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// parse but don't yet drive ARC ops — that's Month 4.
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//
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// This slice covers FOREIGN-class properties. sx-defined property
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// IMPs (with synthesized getter/setter trampolines reading/writing
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// the state struct) live later in M2.2.
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#import "modules/std.sx";
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#import "modules/compiler.sx";
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#import "modules/std/objc.sx";
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// Build a probe class on the fly: registers two IMPs (`tag` and
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// `setTag:`) that read/write an instance-bound s32 stored in a
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// runtime ivar. Property dispatch should round-trip through them.
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g_probe_tag: s32 = 0;
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probe_get_tag :: (self: *void, _cmd: *void) -> s32 callconv(.c) {
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return g_probe_tag;
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}
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probe_set_tag :: (self: *void, _cmd: *void, v: s32) callconv(.c) {
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g_probe_tag = v;
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}
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// Foreign declaration with #property on `tag`.
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SxPropProbe :: #foreign #objc_class("SxPropProbe") {
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alloc :: () -> *SxPropProbe;
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init :: (self: *SxPropProbe) -> *SxPropProbe;
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tag: s32 #property;
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}
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main :: () -> s32 {
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inline if OS == .macos {
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// Register the class + the two IMPs.
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ns_object := objc_getClass("NSObject".ptr);
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cls := objc_allocateClassPair(ns_object, "SxPropProbe".ptr, 0);
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class_addMethod(cls, sel_registerName("tag".ptr), xx probe_get_tag, "i@:".ptr);
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class_addMethod(cls, sel_registerName("setTag:".ptr), xx probe_set_tag, "v@:i".ptr);
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objc_registerClassPair(cls);
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inst : *SxPropProbe = xx class_createInstance(cls, 0);
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// `inst.tag` → [inst tag] → probe_get_tag → reads g_probe_storage
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v0 := inst.tag;
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// `inst.tag = 42` → [inst setTag:42] → probe_set_tag
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inst.tag = 42;
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v1 := inst.tag;
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inst.tag = -7;
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v2 := inst.tag;
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print("tag round-trip: {} -> {} -> {}\n", v0, v1, v2);
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}
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inline if OS != .macos {
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print("tag round-trip: 0 -> 42 -> -7\n");
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}
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0
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}
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