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).
62 lines
2.1 KiB
Plaintext
62 lines
2.1 KiB
Plaintext
// `xx closure : Block` for an arbitrary closure signature.
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//
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// The stdlib (modules/std/objc_block.sx) declares hand-rolled
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// `Into(Block) for Closure() -> void` and `Closure(bool) -> void`
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// impls — the two most common Apple block shapes. Other signatures
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// need a per-shape `__block_invoke_<sig>` trampoline + `Into(Block)`
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// impl declared somewhere reachable (stdlib if shared, in-file if
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// app-specific).
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//
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// This test exercises the user-declared variant: signature
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// `Closure(s32, *void) -> void` (a two-arg block — not in stdlib).
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// If the impl is missing, the compiler emits a focused diagnostic
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// pointing at modules/std/objc_block.sx as the template.
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#import "modules/std.sx";
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#import "modules/std/objc_block.sx";
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// Trampoline matching `void (^)(int, void*)` — the C ABI Apple's
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// runtime calls. Forwards through to the sx closure with the
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// standard `(__sx_ctx, env, ...args)` shape.
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__block_invoke_void_s32_p :: (block_self: *Block, arg0: s32, arg1: *void) callconv(.c) {
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typed_fn : (*void, s32, *void) -> void = xx block_self.sx_fn;
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typed_fn(block_self.sx_env, arg0, arg1);
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}
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impl Into(Block) for Closure(s32, *void) -> void {
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convert :: (self: Closure(s32, *void) -> void) -> Block {
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.{
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isa = @_NSConcreteStackBlock,
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flags = 0,
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reserved = 0,
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invoke = xx @__block_invoke_void_s32_p,
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descriptor = xx @__sx_block_descriptor,
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sx_env = self.env,
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sx_fn = self.fn_ptr,
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}
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}
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}
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// Side-effect capture so we can observe both args reached the
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// closure body.
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g_sum: s32 = 0;
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g_tag: *void = null;
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main :: () -> s32 {
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cl := (n: s32, tag: *void) => {
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g_sum = n + 1;
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g_tag = tag;
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};
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b : Block = xx cl;
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invoke_fn : (*Block, s32, *void) -> void callconv(.c) = xx b.invoke;
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sentinel: s32 = 42;
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invoke_fn(@b, 41, xx @sentinel);
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if g_sum != 42 { print("FAIL: g_sum expected 42, got {}\n", g_sum); return 1; }
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if g_tag == null { print("FAIL: g_tag null\n"); return 1; }
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print("block multi-arg ok: sum={}\n", g_sum);
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0
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}
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