d2cba4e460
The type-convergence side of E1.4 (the SCC slice). A bare `-> !` function's error set is now converged whole-program from its literal raises plus the sets of the pure-failable functions it `try`s. - convergeInferredErrorSets: a pre-lowering fix-point pass (lowerRoot Pass 1d, after scanDecls / before body lowering) that walks each top-level bare-`!` function's body AST (collectErrorSites, stopping at nested-fn boundaries) for literal `raise error.X` tags + pure `try g()` edges, then unions each set with its edges' sets until stable. Stored in a side map `inferred_error_sets` (fn name -> sorted []u32) — sidesteps the name-only error-set interning collision (the shared `!` placeholder stays empty). - lowerTry widening: a named caller `try`-ing a bare-`!` callee now checks the callee's converged set (previously a false-negative — the empty placeholder was trivially a subset). Factored diagTagsNotInSet out of checkErrorSetSubset. - empty-inferred warning: a top-level non-main bare-`!` function with an empty converged set warns. Not user-visible yet (the compile driver renders diagnostics only on failure — a LANG follow-up), so unit-tested on the DiagnosticList. - corrected two now-stale bail messages (failable-`or` -> E2.4; value-carrying `try` -> E2). Deferred to E2.4: failable-`or` chains / value-terminators (and `try` fallback routing) — gated on the value-carrying tuple ABI. Tests: examples/223-inferred-error-sets.sx (transitive convergence + widening passes, exit 7), examples/224-inferred-widening-reject.sx (transitive widening rejection, exit 1), unit test in lower.test.zig. Gates: zig build, zig build test, 262/262 examples.
41 lines
1.3 KiB
Plaintext
41 lines
1.3 KiB
Plaintext
// Whole-program inferred error sets (ERR step E1.4b). A bare `-> !` function's
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// error set is INFERRED: the union of the tags it raises directly plus the
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// sets of the failable functions it `try`s, converged across the whole call
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// graph by a fix-point pass. Here `leaf` raises {Foo}; `mid` try-propagates
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// leaf AND raises Bar, so `mid` converges to {Foo, Bar}; the named caller
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// `run :: -> !A` then type-checks because mid's converged set is a subset of
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// A. The rejection (a converged tag NOT in the caller's set) lives in
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// `examples/224-inferred-widening-reject.sx`.
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#import "modules/std.sx";
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A :: error { Foo, Bar }
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leaf :: (n: s32) -> ! {
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if n < 0 { raise error.Foo; }
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return;
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}
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// Inferred set converges to {Foo, Bar}: {Foo} absorbed from `try leaf` plus
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// the directly-raised Bar.
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mid :: (n: s32) -> ! {
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try leaf(n);
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if n == 100 { raise error.Bar; }
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return;
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}
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// Named caller: mid's converged {Foo, Bar} is a subset of A -> widening OK.
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run :: (n: s32) -> !A {
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try mid(n);
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return;
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}
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main :: () -> s32 {
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e := run(-1); // leaf raises Foo -> propagates out
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r : s32 = 0;
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if e == error.Foo { r = r + 7; } // true -> +7
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if e == error.Bar { r = r + 1; } // false (Foo escaped, not Bar)
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print("inferred result: {}\n", r); // -> 7
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return r;
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}
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