fix min/max variadic fold#1
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The fold expression `(r = std::min(arg0, args)), ...` compared `arg0` against each successive `args` element instead of folding through `r`, so for three or more arguments the result was `min(arg0, last_arg)` rather than the true minimum. e.g. `min(5, 3, 7)` returned 5. The single-argument overload (empty parameter pack) returned `r` without ever assigning it — undefined behavior. Initialize `r = arg0` and fold through `r`. Same fix for `maxv`.
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The fold expression
(r = std::min(arg0, args)), ...comparedarg0against each successiveargselement instead of folding throughr, so for three or more arguments the result wasmin(arg0, last_arg)rather than the true minimum. e.g.min(5, 3, 7)returned 5.The single-argument overload (empty parameter pack) returned
rwithout ever assigning it — undefined behavior.Initialize
r = arg0and fold throughr. Same fix formaxv.