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).
80 lines
2.6 KiB
Plaintext
80 lines
2.6 KiB
Plaintext
// Phase 0 baseline (PLAN-FFI.md step 0.9): FFI result chains. The
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// shapes that real sx code uses for opaque C handles (MTLBuffer*,
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// AAssetManager*, file pointers, ...) — passing a C-returned
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// pointer into another C call, stashing it in a struct field,
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// pushing into a `List(*void)`, and iterating that list to feed each
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// handle back through C.
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//
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// No new ABI shape — pointer-in, pointer-out. The lemma locked in:
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// handle-shaped flows survive sx's struct-field assignment, List
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// storage, and iteration-then-call cycles.
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#import "modules/std.sx";
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#import c {
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#include "1217-ffi-09-foreign-result-chain.h";
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#source "1217-ffi-09-foreign-result-chain.c";
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};
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// Struct field hosts an FFI-returned handle.
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Counter :: struct {
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handle: *void = null;
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label: string;
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}
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main :: () -> s32 {
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// ── 1. Chain: make → bump → peek ───────────────────────────────
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a := ffi_chain_make(100);
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print("peek after make = {}\n", ffi_chain_peek(a));
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print("bump(+5) = {}\n", ffi_chain_bump(a, 5));
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print("bump(+3) = {}\n", ffi_chain_bump(a, 3));
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print("peek after bumps = {}\n", ffi_chain_peek(a));
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// ── 2. Stash handle in a struct field, use through `.handle` ──
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c : Counter = .{ handle = ffi_chain_make(50), label = "ctr-a" };
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print("ctr label = {}\n", c.label);
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print("ctr peek = {}\n", ffi_chain_peek(c.handle));
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ffi_chain_bump(c.handle, 7);
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print("ctr after bump = {}\n", ffi_chain_peek(c.handle));
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// ── 3. Push handles into a List, iterate, feed back to C ──────
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handles : List(*void) = .{};
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i : s32 = 0;
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while i < 3 {
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h := ffi_chain_make(i * 10);
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handles.append(h);
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i += 1;
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}
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j : s64 = 0;
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while j < handles.len {
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h := handles.items[j];
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v := ffi_chain_peek(h);
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print("list[{}] peek = {}\n", j, v);
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j += 1;
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}
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// Iterate again, bump each, observe the cumulative effect.
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j = 0;
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while j < handles.len {
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ffi_chain_bump(handles.items[j], 1);
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j += 1;
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}
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j = 0;
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while j < handles.len {
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print("list[{}] after bump= {}\n", j, ffi_chain_peek(handles.items[j]));
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j += 1;
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}
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// ── Cleanup ─────────────────────────────────────────────────────
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ffi_chain_dispose(a);
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ffi_chain_dispose(c.handle);
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j = 0;
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while j < handles.len {
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ffi_chain_dispose(handles.items[j]);
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j += 1;
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}
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0
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}
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