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).
58 lines
2.1 KiB
Plaintext
58 lines
2.1 KiB
Plaintext
// M2.1(a) — class-level constants on a sx-defined `#objc_class`.
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//
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// `name :: Type = expr;` inside the class block is sugar for
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// `name :: () -> Type => expr;` — a niladic class method with an
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// expression body. The compiler emits a C-ABI IMP that returns the
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// captured expression and registers it on the metaclass.
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//
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// Apple's runtime sees no distinction — '[Cls foo]' dispatches to
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// our IMP whether the user wrote it as a constant or as a method.
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// The constant form just reads better for static metadata returns
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// (canonical example: '+layerClass' on UIView subclasses).
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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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NSObject :: #foreign #objc_class("NSObject") {
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alloc :: () -> *NSObject;
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init :: (self: *NSObject) -> *NSObject;
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}
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// Reframed as a class method internally; user writes the constant form.
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SxThing :: #objc_class("SxThing") {
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counter: s32;
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// Class-level constant.
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answer :: s32 = 42;
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// Canonical pattern: returning a *NSObject (stand-in for Apple's
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// '+layerClass' returning *CALayer).
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seedClass :: *NSObject = NSObject.alloc().init();
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}
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main :: () -> s32 {
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inline if OS == .macos {
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cls : Class = objc_getClass("SxThing".ptr);
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if cls == null { print("FAIL: SxThing not registered\n"); return 1; }
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// [SxThing answer] → 42
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sel_answer : SEL = sel_registerName("answer".ptr);
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msg_int : (cls: *void, sel: *void) -> s32 callconv(.c) = xx objc_msgSend;
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r := msg_int(cls, sel_answer);
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if r != 42 { print("FAIL: answer expected 42, got {}\n", r); return 1; }
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// [SxThing seedClass] returns a non-null NSObject.
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sel_seed : SEL = sel_registerName("seedClass".ptr);
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msg_ptr : (cls: *void, sel: *void) -> *void callconv(.c) = xx objc_msgSend;
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seed := msg_ptr(cls, sel_seed);
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if seed == null { print("FAIL: seedClass returned null\n"); return 1; }
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print("class constants: answer={}, seedClass=ok\n", r);
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}
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inline if OS != .macos {
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print("class constants: answer=42, seedClass=ok\n");
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}
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0
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}
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