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).
63 lines
2.8 KiB
Plaintext
63 lines
2.8 KiB
Plaintext
// Feature 1 / Step 0.4 — tuple baseline probe (gate for Decision 2:
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// "tuples are first-class for pack storage").
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//
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// This file is the audit artifact: it exercises every tuple operation the
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// canonical `Combined`/`map` body relies on, EXCEPT the two pack/tuple
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// projection+spread sugars that are themselves Feature 1 work (documented
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// as gaps at the bottom). Everything here RUNS today.
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//
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// Run: ./zig-out/bin/sx run examples/probes/tuple-baseline.sx
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#import "modules/std.sx";
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Listenable :: struct { value: s64; } // stand-in element struct
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Combined :: struct { sources: (s32, s32); } // tuple-typed field (Decision 2)
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swap :: (a: s64, b: s64) -> (s64, s64) { (b, a) }
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fst :: (t: (s64, s64)) -> s64 { t.0 }
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main :: () -> s32 {
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// ── Block A — primitives (WORKS) ───────────────────────────────
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pair := (40, 2); // inferred positional
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print("A.idx {} {}\n", pair.0, pair.1);
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named := (x: 10, y: 20); // named + numeric access
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print("A.named {} {} {}\n", named.x, named.0, named.1);
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one := (42,); // 1-tuple
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print("A.one {}\n", one.0);
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a : s64 = pair.0; // element into typed local
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print("A.local {}\n", a);
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// ── Block B — storage in a struct field (WORKS; core of Decision 2)
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c : Combined = ---;
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c.sources = (7, 9); // assign tuple value to field
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print("B.field {} {}\n", c.sources.0, c.sources.1);
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// ── Block C — return / pass / operators (WORKS) ────────────────
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s := swap(1, 2);
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print("C.ret {} {}\n", s.0, s.1);
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print("C.pass {}\n", fst((11, 22)));
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print("C.eq {}\n", (1, 2) == (1, 2));
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cc := (1, 2) + (3, 4);
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print("C.concat {} {}\n", cc.0, cc.3);
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print("C.mem {}\n", 3 in (1, 2, 3));
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0
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}
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// ── GAPS (Feature 1 work — intentionally NOT exercised above) ──────
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//
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// G1. Tuple field projection across elements:
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// t := (Listenable.{value=1}, Listenable.{value=2});
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// v := t.value; // expected: (1, 2) — Decision 3 "tuple.field"
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// Today: `error: field 'value' not found on type 'tuple'`.
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// Needed by canonical `self.sources.value`.
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//
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// G2. Tuple spread into call args:
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// p := (10, 20);
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// add(..p); // expected: add(10, 20) — Decision 3 "..tuple"
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// Today: lowers to one `undef` arg → LLVM arity verification failure.
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// Needed by canonical `mapper(..sources.value)` and `(..sources)`.
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//
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// Both are already scheduled: parsing in Phase 1.2 (PackExpansion node covers
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// `(..pack)` / `..pack.field`), sema in Phase 2.3 ("tuple-spread parallels").
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// No separate Feature 1.5 needed — see Step 0.4 triage in CHECKPOINT-LANG.md.
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