Fix #422: tensor sub simplifier round-7 parity (0 - (-A) built nested negative) - #423
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Fix #422: tensor sub simplifier round-7 parity (0 - (-A) built nested negative)#423petlenz wants to merge 1 commit into
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…/dispatch(negative) through operator- Signed-off-by: petlenz <peterlenz89.pl@gmail.com>
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Closes #422.
Round-7 (001164d) routed
sub_base::dispatch(zero)anddispatch(negative)throughoperator-in the scalar and t2s domains; the tensor domain was missed and still built raw negative nodes:dispatch(tensor_zero):0 - (-A)producednegative(negative(A))instead ofA.dispatch(tensor_negative): a sum that itself normalizes to a negative re-wrapped into a nested negative (the scalar R7-1 shape).Both now route through
operator-(whosetag_invoke(neg_fn, ...)already folds-0 → 0and-(-x) → x). Behavior preserved: the0 - 0special case flows through the operator's zero branch; the tensor-specificis_validguard on the negative-lhs path (tensor add can yield an invalid holder on full cancellation) stays.Found downstream: numsim-codegen's emitters received the nested-negative node and produced invalid C++ (
--A) until they grew a defensive paren guard (numsim-codegen#136 / PR numsim-codegen#147, which keeps its guard as defense-in-depth).Test:
RoundSevenReview.TensorSubNormalizesLikeScalarAndT2s—0-(-A) → A,0-0 → 0,(-A)-(-A) → 0(notnegative(zero)),(-A)-B → -(A+B)unchanged. Full suite: 2311/2311 green locally (gcc-14 Debug).