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).
38 lines
1.2 KiB
Plaintext
38 lines
1.2 KiB
Plaintext
// Regression test for issue-0025 path B.
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//
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// When a fn-pointer's type is spelled with `callconv(.c)`, the indirect
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// call must apply the same C-ABI byval coercion that direct C-ABI calls
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// do at the call site (path A): >16-byte non-HFA aggregates are passed
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// as `ptr byval(<T>)`. Without the fix, the indirect call site builds
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// an LLVM function type whose param slot is the raw struct, which the
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// AArch64/x86_64 backend tries to lay out across registers + stack in
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// ways that don't match the byval-attributed callee signature — the
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// callee then reads garbage out of the wrong machine-state slots.
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//
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// The opt-in is the `callconv(.c)` on the fn-pointer type spelling.
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// Pure-sx fn-pointer casts (no callconv suffix) keep their default
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// calling convention — verified by examples/87-fnptr-cast-large-aggregate.sx.
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#import "modules/std.sx";
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Wide :: struct {
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a: s64;
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b: s64;
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c: s64;
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d: s64;
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}
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accept_c :: (w: Wide) -> s64 callconv(.c) {
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w.a + w.b + w.c + w.d
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}
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main :: () -> s32 {
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w := Wide.{ a = 1, b = 10, c = 100, d = 1000 };
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if accept_c(w) != 1111 { return 1; }
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fn_ptr : (Wide) -> s64 callconv(.c) = xx accept_c;
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if fn_ptr(w) != 1111 { return 2; }
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0
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}
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