Fix: PeelWhereChain rebases onto innermost (narrowest) predicate param#480
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When aggregate fusion peels a chain of Where calls with mixed parameter types (e.g. Where<Derived>(p).Where<Base>(q).Sum(...) produced by IQueryable<out T> covariance), rebasing every peeled body onto the outer widest parameter threw ArgumentException on any member that only exists on a narrower type. Rebasing onto the innermost parameter is always safe because every derived type contains all base/interface members. Made-with: Cursor
…ate peel The non-fusable Sum/Min/Max/Avg peel path rebuilt the Where call with the predicate unconditionally wrapped in Expression.Quote. That is correct for Queryable.Where (parameter type is Expression<Func<>>) but throws ArgumentException for Enumerable.Where (parameter type is Func<>), which is what g.Where(p) on an IGrouping resolves to. Quote only when the captured innermost Where method expects an Expression-derived parameter. Made-with: Cursor
Seed the AndAlso accumulator from peeled[^1].Body (already typed against the rebase parameter) and iterate only the outer predicates that need rebasing. Drops the per-iteration null check and reduces FastExpression.Lambda allocations from one-per-predicate to one total. Made-with: Cursor
… place source is already a ref Expression; the local copy and final write-back were redundant. The bail-out branches naturally leave source at the unconsumed remainder. Made-with: Cursor
SergeiPavlov
approved these changes
Apr 25, 2026
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When aggregate fusion peels a chain of
Wherecalls with mixed parameter types (e.g.Where<Derived>(p).Where<Base>(q).Sum(...)produced byIQueryable<out T>covariance), rebasing every peeled body onto the outer widest parameter threwArgumentExceptionon any member that only exists on a narrower type. Rebasing onto the innermost parameter is always safe because every derived type contains all base/interface members.The non-fusable
Sum/Min/Max/Avgpeel path rebuilt theWherecall with the predicate unconditionally wrapped inExpression.Quote. That is correct forQueryable.Where(parameter type isExpression<Func<>>) but throwsArgumentExceptionforEnumerable.Where(parameter type isFunc<>), which is whatg.Where(p)on anIGroupingresolves to. Quote only when the captured innermostWheremethod expects an Expression-derived parameter.Made-with: Cursor