959845bd30
The canonical sx block-body lambda is `(params) { stmts }` (and
`(params) -> Ret { stmts }`); the arrow form `=>` is for EXPRESSION bodies
(`(params) => expr`). The arrow-block hybrid `(params) => { .. }` was being
used in 33 files — convert all of them by dropping the `=>`. The two forms are
exactly equivalent (verified: identical IR and identical runtime values — the
block tail is the value with or without a `-> Ret`), so this is a pure source
cleanup: no `.ir` churn, and the only snapshot change is 0923's diagnostic
COLUMN (a negative narrowing test whose error span shifted by the removed `=> `).
Arrow EXPRESSION bodies (`=> expr`, `=> .{..}`, `=> [..]`) and `=>` inside
comments/strings were left untouched. Migrated across examples/concurrency,
examples/{closures,ffi-objc,generics,optionals,types}, issues/, and the stdlib
(io.sx, sched.sx). Suite 855/0.
24 lines
1.0 KiB
Plaintext
24 lines
1.0 KiB
Plaintext
// Flow narrowing (issue 0179) does NOT cross into a nested function body. A
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// closure capturing a local that is narrowed in the ENCLOSING scope still sees
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// it as `?T` inside the closure — using it unguarded is a compile error.
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//
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// This guards the soundness fix from the adversarial review of 0179/0185: the
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// narrowing gate is keyed by per-function SSA `Ref`, and a closure body's `Ref`
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// space overlaps the enclosing function's, so without isolation an outer
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// narrowed `Ref` would falsely permit unwrapping a not-proven-present optional
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// inside the closure (`Lowering.NarrowGuard`). The closure could run later when
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// the captured value is null, so the reject is mandatory — write `n!` to assert.
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#import "modules/std.sx";
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takes_i64 :: (x: i64) { print("{}\n", x); }
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main :: () {
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n : ?i64 = 7;
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if n != null {
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// `n` is narrowed HERE, but the closure body is a separate function:
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// `n` is `?i64` inside it, so this implicit unwrap must be rejected.
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g := () { takes_i64(n); };
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g();
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}
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}
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