296c809d85
A `v, err := failable()` destructure now binds the value slot(s) "live
only where `err` is proven absent". Reading `v` where the compiler cannot
prove `err == null` is a compile error.
New diagnostic-only Pass 1e (`checkErrorFlow` in ir/lower.zig): a
structured, path-sensitive walk over each main-file function body. A
proven-null set is threaded across branches and joined by intersection
at each `if`'s merge. Proof shapes recognized:
- `if !err { … v … }` (proven inside the guard)
- `if err { return/raise } … v` (proven on the fall-through)
- `if err { … } else { … v … }` (proven in the else branch)
- `!err and <reads v>` (short-circuit refinement)
Error-set tag compares (`if err == error.X`) prove nothing about
absence — they narrow the tag only. Nested lambdas are analyzed as their
own boundaries. Library modules are trusted (skipped).
Migrated the canon value-failable examples (1011/1012/1018/1044) to read
their value slots under `if !err` guards — output unchanged. New
regressions: 1046 (every proof shape compiles + runs, exit 210) and 1047
(unproven reads rejected, exit 1).
Gates: zig build, zig build test, run_examples.sh -> 338 passed, 0 failed.
12 lines
781 B
Plaintext
12 lines
781 B
Plaintext
error: value `v` from a failable can be used only where its error `err` is proven absent — guard the use with `if !err { … }`, or return early with `if err { return; }` before reading `v`
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--> /Users/agra/projects/sx/examples/1047-errors-value-slot-liveness-reject.sx:22:21
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22 | if err { return v; } // REJECTED: err present on this path
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| ^
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error: value `v` from a failable can be used only where its error `err` is proven absent — guard the use with `if !err { … }`, or return early with `if err { return; }` before reading `v`
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--> /Users/agra/projects/sx/examples/1047-errors-value-slot-liveness-reject.sx:30:12
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30 | return v; // REJECTED: err not proven absent
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| ^
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