Files
sx/examples/1057-errors-negated-error-binding.sx
agra a8fbded567 fix(0129): logical not is truthiness-aware, not a bit flip
The unary .not arm emitted bool_not (LLVM bitwise Not) for every
operand. Correct on i1; on an error binding — an error-set value, u32
tag at the LLVM level — a bitwise not of a nonzero tag stays nonzero,
so 'if !e' held even on a SET error and its branch read the
uninitialized success value (real segfault in the distribution repo's
sqlite tests). Plain integers had the same hole ('!7' was '~7').

Now: bool keeps bool_not; integers and error-set operands lower as the
truthiness complement (cmp_eq against a typed zero); anything else is
diagnosed instead of silently bit-flipped.

Regression: examples/1057 (set error: !e must not hold; success: !e
holds with a real value; integer truthiness) + examples/1171 (!"text"
diagnosed); both FAIL pre-fix. zig build test 426/426;
tests/run_examples.sh 600/600.
2026-06-12 13:36:54 +03:00

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// `!` on an error binding is the truthiness complement of `if e` (issue
// 0129). Pre-fix, `!` lowered as a bitwise not, so a nonzero error tag
// stayed nonzero and `if !e` held even on a SET error — with the success
// value read as garbage. Integer operands get the same `!x ≡ x == 0`
// semantics.
#import "modules/std.sx";
E :: error { Boom }
f :: (fail: bool) -> (i64, !E) {
if fail { raise error.Boom; }
return 42;
}
main :: () -> i32 {
// set error: `if e` holds, `if !e` must NOT
v, e := f(true);
took_e := false;
if e { took_e = true; }
if !e { print("BUG: !e held on a set error (v={})\n", v); return 1; }
if !took_e { print("BUG: if e did not hold on a set error\n"); return 2; }
// success: `if !e` holds and the value is real
v2, e2 := f(false);
if e2 { print("BUG: e2 set on success\n"); return 3; }
if !e2 { print("ok: !e2 on success, v2={}\n", v2); }
// integers: `!n` is `n == 0`, not a bit flip
n := 7;
if !n { print("BUG: !7 held\n"); return 4; }
z := 0;
if !z { print("ok: !0 holds\n"); }
print("done\n");
return 0;
}