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).
30 lines
838 B
Plaintext
30 lines
838 B
Plaintext
// Pure-sx fn-pointer cast: a function-pointer typed without `callconv(.c)`
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// keeps the default (sx) calling convention. Passing a >16-byte aggregate
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// through that pointer must not get the C-ABI byval coercion — the sx-CC
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// callee expects the struct as an SSA value, not as a `ptr byval(<T>)`.
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//
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// Pair with examples/86-callconv-c-fnptr-large-aggregate.sx, which covers
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// the opposite arm (fn-pointer typed `callconv(.c)` does get byval).
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#import "modules/std.sx";
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Wide :: struct {
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a: s64; b: s64; c: s64; d: s64;
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}
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accept :: (w: Wide) -> s64 {
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w.a + w.b + w.c + w.d
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}
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main :: () -> s32 {
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w := Wide.{ a = 1, b = 10, c = 100, d = 1000 };
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direct := accept(w);
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if direct != 1111 { return 1; }
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fn_ptr : (Wide) -> s64 = xx accept;
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indirect := fn_ptr(w);
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if indirect != 1111 { return 2; }
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0
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}
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