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).
26 lines
1.1 KiB
Plaintext
26 lines
1.1 KiB
Plaintext
// Scalar binary operators check operand-type compatibility. The result
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// type is otherwise taken from the left operand, so mixing a non-numeric
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// type (here `string`) would lower as `<op> : s64` and either reinterpret
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// the string's bytes (arithmetic / bitwise → garbage) or feed mismatched
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// types to `icmp` (ordering → LLVM verifier failure). All such mismatches
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// are now rejected at compile time:
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// - arithmetic `+ - * / %` (numeric / vector / pointer operands)
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// - ordering `< <= > >=` (numeric / enum / pointer operands)
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// - bitwise `& | ^` (integer / enum operands)
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// - shift `<< >>` (integer / enum operands)
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// Legitimate mixes (int+float promotion, flags-enum bitwise, enum/pointer
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// comparison) are unaffected — see `examples/50-smoke.sx`.
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#import "modules/std.sx";
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main :: () -> s32 {
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n : s64 = 40;
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s : string = "nope";
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a := n + s; // arithmetic: s64 + string
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b := s * n; // arithmetic: non-numeric LHS (string * s64)
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c := n < s; // ordering: s64 < string
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d := n & s; // bitwise: s64 & string
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e := n << s; // shift: s64 << string
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0
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}
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