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).
54 lines
2.1 KiB
Plaintext
54 lines
2.1 KiB
Plaintext
// Phase 0 baseline (PLAN-FFI.md step 0.3): structs >16 bytes passed
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// by value into a C `#foreign` fn and returned by value. Exercises
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// the byval-pointer ABI path — the caller copies the struct onto its
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// stack and hands a pointer to the callee; on AAPCS64 the return
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// uses the indirect `x8` register; on SysV AMD64 the return is a
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// hidden first arg pointer that the caller allocates.
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//
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// Distinct from the register-pair / [2 x i64] / HFA paths the
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// small-struct baseline (ffi-02) covers. The two relevant emit_llvm
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// helpers are `needsByval` (returns true when size > 16) and
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// `materializeByvalArg` (alloca + store + pass pointer).
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//
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// Big24 — 24 B, three s64
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// Big48 — 48 B, six s64
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#import "modules/std.sx";
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#import c {
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#source "1211-ffi-03-large-struct.c";
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};
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Big24 :: struct { a: s64; b: s64; c: s64; }
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Big48 :: struct {
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a: s64; b: s64; c: s64;
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d: s64; e: s64; f: s64;
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}
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ffi_big24_make :: (a: s64, b: s64, c: s64) -> Big24 #foreign;
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ffi_big24_rotate :: (v: Big24) -> Big24 #foreign;
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ffi_big24_sum :: (v: Big24) -> s64 #foreign;
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ffi_big48_make :: (a: s64, b: s64, c: s64,
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d: s64, e: s64, f: s64) -> Big48 #foreign;
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ffi_big48_reverse :: (v: Big48) -> Big48 #foreign;
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ffi_big48_sum :: (v: Big48) -> s64 #foreign;
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main :: () -> s32 {
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// ── Big24 (24 bytes, byval pointer) ────────────────────────────
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v := ffi_big24_make(1, 2, 3);
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print("big24 make = ({}, {}, {})\n", v.a, v.b, v.c);
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w := ffi_big24_rotate(v);
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print("big24 rotate = ({}, {}, {})\n", w.a, w.b, w.c);
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print("big24 sum = {}\n", ffi_big24_sum(v));
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// ── Big48 (48 bytes, byval pointer) ────────────────────────────
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x := ffi_big48_make(10, 20, 30, 40, 50, 60);
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print("big48 make = ({}, {}, {}, {}, {}, {})\n", x.a, x.b, x.c, x.d, x.e, x.f);
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y := ffi_big48_reverse(x);
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print("big48 reverse = ({}, {}, {}, {}, {}, {})\n", y.a, y.b, y.c, y.d, y.e, y.f);
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print("big48 sum = {}\n", ffi_big48_sum(x));
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0
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}
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