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).
33 lines
1.3 KiB
Plaintext
33 lines
1.3 KiB
Plaintext
// Extern data globals via `<name> : <type> #foreign;`. Lets sx code
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// reference libSystem / framework symbols (NSConcreteStackBlock,
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// __stdinp, etc.) for FFI bridges. Mirrors the long-standing
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// `<fn> :: (...) -> ... #foreign;` form on the function side.
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//
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// Cross-file dimension (PLAN-FFI step 0.10): the helper companion
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// `94-foreign-global-helper.sx` ALSO declares `__stdinp : *void #foreign;`.
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// Both files referencing the same extern symbol must link cleanly —
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// LLVM dedupes the named global, the C linker resolves both refs to
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// the one libSystem symbol.
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//
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// We *don't* check that the helper computes the same address — see
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// issue-0037 (helper-function-scoped `@foreign_global` lowers to
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// undef today). When that fixes, fold the helper's address back into
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// the equality check here.
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#import "modules/std.sx";
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#import "1205-ffi-foreign-global-helper.sx";
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__stdinp : *void #foreign;
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main :: () -> s32 {
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addr_bits : u64 = xx @__stdinp;
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print("stdin extern global non-null: {}\n", addr_bits != 0);
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// Force the helper symbol to participate in linking (otherwise the
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// imported file's #foreign decl might get dropped by the
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// dead-code stripper). The actual return value is busted today
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// — see issue-0037.
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_ := stdinp_addr_present();
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print("helper file linked: true\n");
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0
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}
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