Let C++20 rewriting synthesize sum's operator!=#299
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🤖 Augment PR SummarySummary: This PR removes the hand-written Changes:
Why: Prevents constraint drift where 🤖 Was this summary useful? React with 👍 or 👎 |
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The hand-written `operator!=` dropped the arity conjuncts `operator==` carries, so against a `sum<>` operand its constraint was satisfied while `==`'s was not: the call reported itself viable and then failed to compile in its own body, where `not(lh == rh)` found no `operator==`. A constraint that lies. Deleting it makes `a != b` a rewritten `!(a == b)`, which inherits `operator==`'s constraints by construction, so the two cannot drift apart again. Closes #281 Assisted-by: Claude:claude-opus-4-8[1m]
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Retire #281's tripwires: a rewritten != inherits =='s constraints, so the two now drop out together against the uninstantiable sum<>. The probes move to the equality section, where #299 puts them and where they belong - the noexcept section keeps only what it weighs - and carry both operand orders from #299 plus the empty-on-empty pair the tripwires had. Assisted-by: Claude:claude-opus-4-8[1m]
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The hand-written
operator!=dropped the arity conjunctsoperator==carries, so against asum<>operand its constraint was satisfied while=='s was not: the call reported itself viable and then failed to compile in its own body, wherenot(lh == rh)found nooperator==. A constraint that lies.Deleting it makes
a != ba rewritten!(a == b), which inheritsoperator=='s constraints by construction, so the two cannot drift apart again.Closes #281
Stack: P5 of 13 — the release-0.1 bugfix queue, merging bottom-up into
main. Based on #298 and to be retargeted tomainonce it merges; the diff shows only this PR's commits. Every stack boundary was validated with a gcc build and the full test suite on top ofmain, and the aggregate branch ran the full CI matrix green (#289).