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).
29 lines
1.1 KiB
Plaintext
29 lines
1.1 KiB
Plaintext
// `#foreign` C-variadic tail: trailing `..args: []T` on a foreign fn maps
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// to the C calling convention's `...`. Extras at the call site are
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// passed via the variadic slot with the standard default argument
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// promotion (s8/s16/bool → s32, f32 → f64) applied implicitly.
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#import "modules/std.sx";
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#import c {
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#source "1218-ffi-foreign-cvariadic.c";
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};
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sx_ffi_sum_ints :: (n: s32, ..args: []s32) -> s64 #foreign;
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sx_ffi_avg_doubles :: (n: s32, ..args: []f64) -> f64 #foreign;
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sx_ffi_count_args :: (tag: *u8, ..args: []*u8) -> s32 #foreign;
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main :: () -> s32 {
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print("sum_ints(3, 10, 20, 30) = {}\n", sx_ffi_sum_ints(3, 10, 20, 30));
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print("sum_ints(0) = {}\n", sx_ffi_sum_ints(0));
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print("avg_doubles(2) = {}\n", sx_ffi_avg_doubles(2, 1.5, 2.5));
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print("avg_doubles(3) = {}\n", sx_ffi_avg_doubles(3, 1.0, 2.0, 3.0));
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a := "alpha".ptr;
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b := "beta".ptr;
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g := "gamma".ptr;
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sentinel : *u8 = null;
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print("count_args(3 strs) = {}\n", sx_ffi_count_args("tag".ptr, a, b, g, sentinel));
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0
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}
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