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).
21 lines
764 B
Plaintext
21 lines
764 B
Plaintext
// Companion module for issue-0057 regression. The bug: an `xx <int>` argument
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// to a variadic `format` (a comptime `..$args` pack), inside a function that
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// lives in an IMPORTED module, was mis-typed as the enclosing fn's
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// `target_type` (here `string`) instead of auto-boxing to `Any` — so it
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// monomorphized `__pack_string` and ABI-coerced the 4-byte int as a 16-byte
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// string fat pointer, corrupting memory at runtime. Fixed by clearing
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// `target_type` while lowering pack args.
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#import "modules/std.sx";
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build :: (n: s32) -> string {
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result := "items:\n";
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i : s32 = 0;
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while i < n {
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line := format(" item {}\n", xx i); // <-- the xx-to-Any pack arg
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result = concat(result, line);
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i = i + 1;
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}
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result
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}
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