Files
sx/examples/1422-ffi-jni-env-03-tl-fallback.sx
agra bdd0e96d78 feat(lang): block value requires no trailing ; (Rust-style)
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).
2026-06-02 09:23:50 +03:00

38 lines
1.1 KiB
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// Phase 2 step 2.16c (PLAN-FFI.md): xfail then green for the
// thread-local env fallback in `#jni_call`. When a `#jni_call` site
// has its env arg omitted AND no `#jni_env` block exists in the same
// function (e.g., we're in a helper called FROM such a block), the
// compiler emits a TL load instead of a sema error.
//
// The TL is pushed/popped by the `#jni_env(env) { ... }` enclosing
// scope at runtime; helpers that don't see the lexical scope still
// pick up the env transparently. Cross-function callers no longer
// need to thread env as an explicit parameter.
//
// Today (2.16b only): lowerJniCall errors when env is omitted and
// jni_env_stack is empty, because TL emission isn't wired yet.
#import "modules/std.sx";
g_should_call : bool = false;
// Helper fn — no `#jni_env` block in scope. Without TL fallback this
// errors because the omitted env can't be resolved.
helper :: (target: *void) {
#jni_call(void)(target, "noop", "()V");
}
unused :: (env: *void, target: *void) {
#jni_env(env) {
helper(target);
}
}
main :: () -> s32 {
if g_should_call {
unused(null, null);
}
print("ok\n");
0
}