[CaffeinatedCoder]

Closes #206

Problem

Select(r => (object)r.Rank).Max(), .Min(), .Order(), .OrderDescending() and .OrderBy(x => x) over a value object whose ordering is its own CompareTo were not refused: EF dropped the cast and answered the column's order, Max 3 and Order 1, 2, 3 where memory answers 1 and 3, 2, 1 for a descending CompareTo (measured on SQLite). HandWrittenOrderingInterceptor's Finder judged an ordering operator by its declared type, object here, and looked under a conversion only in a key selector's body (8f6af8b). The same held for a key that reads the boxed value back through ?? or a member of a projection: OrderBy(r => (object?)r.Optional ?? r.Rank) and Select(r => new { Key = (object)r.Rank }).OrderBy(a => a.Key) answered 1, 2, 3 where memory answers 3, 2, 1 (reported by an outside review, measured here at 3d2abfd). And through other operators' lambdas: a grouping's boxed key or elements, GroupBy's, Join's and SelectMany's result selectors, and a subquery's boxed First() as a key, all answering the column's order at d573eef.

Change

The Finder reads the types a sequence's elements have under their boxing: a Select's body unconverted, followed through the operators that pass elements on (Where, Take, Distinct, the orderings, Cast/OfType, Concat and its kind). An operator without a key, or whose key is the element itself, is refused by those types. A key or selector body is read through both sides of a ?? and a ?:, and a member of a projection is followed back to the expression its new or member initializer set it from, in the same lambda or in the Select that built the elements, through nested projections (d573eef). Every LINQ operator binds its lambdas' parameters to what they stand for (the source's elements, each side of a join, SelectMany's collection, GroupBy's key and elements); a grouping's Key reads its key selector, First and its kind read their source's element, and the visitor carries the bindings into nested lambdas, so Select(g => g.Max()) is refused too (8562de6). Query filters go through the same Finder, so such a filter is refused when the model is built. The EF Core README says the cast changes nothing, through ??, a projection's member, a grouping, a join or a subquery too (claim E05-ordering-boxed); changelog line under 2.3.1.

Tests

• QueryShapes' Op axis gains OrderBoxed, OrderByItselfBoxed, MinBoxed and MaxBoxed over every wrapped kind, converter and accessor of the column and nullable sites, green on SQLite, PostgreSQL's translation and SQL Server.
• HandWrittenOrderingTests gains explicit rows: Max, Min, Order, OrderDescending, OrderBy(x => x), a record class, a navigation's Enumerable.Max (which threw a NullReferenceException inside EF before), a Where and Take between the box and the operator, and a query filter.
• Reverting the source fails 33 of 11,095 (24 catalogue rows, 9 explicit).
• d573eef: the Op axis gains OrderByCoalescedBoxed, OrderByProjectedBoxed and MaxProjectedBoxed; explicit rows for a ?? and a ?: key, an anonymous projection's member under OrderBy, Max(a => a.Key) and Select(a => a.Key).Max(), a nested member, a member-init type, a Where in between, a ?? inside the projection, a navigation (a NullReferenceException inside EF before) and a query filter; controls over .Value and a generated ordering still translate. Reverting its source fails 29 (18 catalogue rows, 11 explicit). EF Core tests green (23,341 passed, SQL Server on azure-sql-edge), conventions green.
• 8562de6: the Op axis gains OrderByGroupKeyBoxed and OrderByJoinedBoxed; explicit rows for a grouping's boxed key and elements, GroupBy's, Join's, GroupJoin's and SelectMany's result selectors, SelectMany under Max, and a subquery's and a navigation's boxed First(); controls through a grouping, a join and a subquery over .Value or a generated ordering still translate. Reverting its source fails 21 (12 catalogue rows, 9 explicit). EF Core tests green (24,258 passed), conventions green.
• Full suite green on a merge of this branch with A closed set over a base class that declares a generated member fails with a Metalama error, or its ToString() is replaced #205's and CMTK0005 and CMTK0006 miss a type parameter constrained to a value object by new(), which CMTK0001 reports #207's fix branches (33,026 passed, SQL Server on azure-sql-edge).

Found by a sweep of release/2.3.1 @ dbdd44e for the defect class of #191-#197.

🤖 Generated with Claude Code