468461becc
Optional (?T) operands were implicitly unwrapped without proof of
presence, silently miscompiling a NULL ?T to garbage. Unwraps in
binary ops and other expression positions are now gated on flow
narrowing: a ?T value is only auto-unwrapped where control flow has
established it is non-null (the narrowed_refs set). Outside a narrowed
region, an implicit unwrap is rejected rather than producing garbage.
Touches the lowering pipeline (lower.zig + lower/{call,closure,coerce,
comptime,control_flow,expr,ffi,generic,pack,stmt}.zig). Adds optionals
examples 0919-0923 and closures example 0312 covering flow narrowing,
binop narrowing, no-implicit-unwrap rejection, and no closure leak of
narrowed state. Updates specs.md and readme.md.
34 lines
1.4 KiB
Plaintext
34 lines
1.4 KiB
Plaintext
// Calling a closure VALUE whose parameter is `?T` coerces the argument to the
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// param type, just like a call to a top-level function does: a concrete arg
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// wraps to a present optional, and `null` becomes an absent optional.
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//
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// Regression (issue 0186): the closure-value call path lowered args without
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// coercing to the closure's declared param types, so a concrete `7` arrived as
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// a bare payload (read ABSENT) and `null` reached a `{T,i1}` slot as a bare
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// pointer (LLVM verifier failure). Fixed by typing args against the closure's
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// params (`resolveCallParamTypes`) AND coercing them at the call site
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// (`coerceClosureCallArgs`).
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#import "modules/std.sx";
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main :: () {
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pick := (p: ?i64) -> i64 => {
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if p == null { return -1; }
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return p; // narrowed inside the lambda body
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};
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print("pick 7: {}\n", pick(7)); // 7 (concrete arg wraps present)
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print("pick null: {}\n", pick(null)); // -1 (null arg → absent)
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// also via a closure stored in a struct field
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Holder :: struct { f: Closure(?i64) -> i64; }
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h := Holder.{ f = pick };
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print("h 5: {}\n", h.f(5)); // 5
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print("h null: {}\n", h.f(null)); // -1
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// and via a plain function-pointer VALUE (same coercion contract)
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fp : (?i64) -> i64 = target;
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print("fp 8: {}\n", fp(8)); // 8
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print("fp null: {}\n", fp(null)); // -1
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}
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target :: (p: ?i64) -> i64 { if p == null { return -1; } return p; }
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