[CaffeinatedCoder]

Closes #191, closes #195, closes #197

Problem

The generators refuse a member they introduce when it's written by hand, and an explicit implementation of an interface they implement (CMTK1011, CMTK1008 for comparison). The checks read the value object's own members, and for explicit implementations its base records' too. Everywhere else the value object reaches such a member, the generated one replaced it, or it kept answering beside the generated one, without a word:

• An interface's explicit implementation of a generated interface member is replaced without a diagnostic #191, an interface's explicit implementation. Every type that declares the interface reaches that default until it declares a public member. Max<Bounded>() read the generated MaxValue where IBounded<TSelf>'s threw, and ((IFormattable)Formats.From(1)).ToString(null, null) printed 1 where IFormats answered its own text. Measured for all eleven interfaces of the input class.
• Another assembly's types, an interface's and a base record's, which the rule has missed since phase 11. Metalama lists no private member of a type in another assembly, and an explicit implementation is private. A closed set over a referenced base class that implements IClosedSet<TSelf> explicitly listed two members in All and none through T.All, and EF Core stored the base's name and read no member's name back.
• A base record's public implementation of a generated member is kept as the value object's, or crashes the aspect #197, a base record's public member. A base's static MinValue/MaxValue was the value object's, and none was generated. Its public Value, From, Parse, TryParse, ToString(string?, IFormatProvider?), TryFormat or CompareTo(object) crashed the aspect (LAMA0500). From another assembly a public static one was refused but called "the explicit implementation of …".
• A base record's explicit Create from another project leaves two rule sets #195, a base record's Create. Where the value object reaches the marker only through a base record of another project that implements Create explicitly, TryFrom("x") accepted (its own Create) and generic T.Create("x") refused (the base's).
• Declared through an interface, IConvertible crashed the aspect (LAMA0041), and a closed set's IParsable<TSelf> too (LAMA0512). A closed set's interface that implements IClosedSet<TSelf>.Name or TryParse explicitly was replaced without a word.

Change

• ValueObjectDeclaration.ImplementationsOf (was ExplicitImplementationsOf) asks the interface mapping (INamedType.TryFindImplementationForInterfaceMember) where each member of a generated interface lands. Any implementation other than the value object's own public member is refused, explicit or public, on the value object, a base record or an interface, in any assembly. The error names it, "in its base type X" or "in its interface X", and names a public one by its type and member.
  • An interface's == maps to the record's own, which replaces it in every record, generated or not (measured with a plain record), so it stays allowed with no special case.
  • An interface's explicit implementation of a member of an interface of its own library is not refused. That is .NET's INumberBase<TSelf>, whose UTF-8 bridges are the only such members in .NET 10 (scanned), and which every .NET number replaces. Refusing them would leave no value object able to implement INumberBase<TSelf>. The test compares assembly symbols, never names.
• The names and signatures checked on the value object are checked on each base record, for a base member that implements no interface (a MaxValue alone). MembersNamed leaves an explicit-looking member to the mapping, so a member of another assembly is named once.
• CreateDeclarations asks the mapping where T.Create lands. An explicit one in a base or an interface is CMTK1011, and so is a base's public one beside the value object's own. The error says to declare the marker on the value object itself, which re-implements it. A base's public Create alone is one rule set and builds.
• IConvertible declared through an interface, on the value object or a base record, and a closed set's IParsable<TSelf> through one, are CMTK1011 naming the interface. ClosedSetTypes uses the same lookup for IClosedSet<TSelf>.
• Checked, unchanged: ValueObjectContractAspect.ExplicitlyImplementsEquatableBetween. A record base's synthesized Equals(TBase) implements IEquatable<TBase> before any interface's default.
• Decision 121 records it, with the exception to decision 34 taken in the patch 2.3.1, since the defect shipped in 2.3.0. A build that worked on 2.3.0 can fail on 2.3.1, and each failure names code that never runs or answers beside the generated member. The changelog's Changed section says so. The Generators README ("Write your own members", "Comparison", the Build errors table) and design/aspects.md follow, with four claims in test/oracles/claims.json.

The comparison interfaces answer CMTK1008, as they do for an explicit implementation on the value object itself.

Stacked on #200 (build/open-2-3-1, which opens 2.3.1 from v2.3.0): merge it first. This replaces #193, which targeted release/2.4.0; the fixes moved to the 2.3.1 patch with their issues (epic #198).

Commits: 4a3d9a6 (#191, Found-By: VA, cherry-picked from #193's 466c541), e606d64 (#197 and the closed-set base test, Found-By: VA), 03e199b (#195, Found-By: OR).

Tests

BuildOutcomeTests, beside the existing CMTK1011 cases, 279 in all. The fixture now builds a library that references the base package alone, beside its consumers: a base type there that carries a marker or IClosedSet<TSelf> is no value object or set of its own, as in a consumer's shared project.

• An interface's explicit implementation, 22 rows: one value object per interface of the input class, generic interfaces over TSelf, two interfaces down, through a base record's interface, a record class over string, and from another assembly (CodoMetis.TypeKit.Generators.Probes).
• A base record's member: other-assembly explicit ones (IFormattable, IMinMaxValue), and public ones of each kind. That covers MinValue/MaxValue through IMinMaxValue and by name alone, ToString(string?, IFormatProvider?), CompareTo(object), Parse/TryParse, Value, From and TryFormat, plus a public static from the library, named once as public.
• Create: an explicit one in the library's base with and without the value object's own, and a public one beside it. Building: the marker declared again over the explicit base, and a public base Create alone.
• Closed sets: IClosedSet<TSelf> through an interface of either assembly, over the library's base class, and IParsable<TSelf> through an interface.
• What builds: a ToString() seam, a Uri's missing ordering, an interface's ==, and a full INumberBase<TSelf> value object. These pass on the old code too, so they pin behaviour. MetersAsNumber is also the guard of the INumberBase exclusion.

Reverted (verify-the-guard). Each seed was run against BuildOutcomeTests:

Seed	Fails
The source back to release/2.4.0 (263 tests, before the second round)	30: the 22 interface rows, 2 other-assembly base records, 4 set rows, plus Every_error_is_one_of_the_intended_ones and Nested_value_objects_... (LAMA0041)
Skip implementations declared in an interface	22: the 19 interface rows that aren't IConvertible, and 3 set interface rows
Skip implementations from another assembly	6: the library interfaces, base records and set
Drop the INumberBase exclusion	3: MetersAsNumber, and the CS0535 guards
Drop IConvertible through an interface / through a base's interface	4 / 3: those rows, plus the LAMA0041 guards
Drop a set's IParsable through an interface	3: that row, plus the LAMA0512 guards
The source back to 466c541 (279 tests)	15: the 9 public base rows, the named-once fact, the 3 Create rows, plus the LAMA guards
Skip a base's public implementation in the mapping	5: InheritsPublicObjectOrder, InheritsLibraryPublicMinMax, the named-once fact, plus the LAMA guards
Check names on the value object alone	6: Value, From, MinValue/MaxValue by name, TryFormat, plus the LAMA guards
Name a public member as Metalama displays it	3: the library rows and the named-once fact
Let the name check report explicit-looking members	1: the named-once fact
Skip Create in the mapping	5: the three Create rows, plus the LAMA guards
Refuse a base's public Create alone	1: OnlyPublicBase

Variants. Input class GTS: a generated member or an explicit implementation of one, by where it sits (the value object, a base record, an interface, two interfaces down, a base record's interface, another assembly) and by which member or interface, over a record struct and a record class, plain and validated, over int, long, double, string and Uri.

Generation review (weaving-review). For each way the refusal could hit correct code there is a control above. A hand-written CompareTo(TSelf) on the value object is its own public member, which the mapping leaves to the existing checks. No name strings, no run-time change, no Native AOT surface.

Not in this PR:

• IValueObject<,> declared through your own interface still fails the aspect with LAMA0512 (A value object implementing an interface derived from IValueObject<,> fails with a Metalama error naming nothing #192).
• A seam inherited from a base record, CompareTo(TSelf) and TryFrom, is An inherited CompareTo(TSelf) is not seen: EF Core orders by the column, and < overflows the stack #194, which also overflows the stack on <.
• A hand-written Equals(TBase) is A hand-written Equals(TBase) on a value object is kept, and a collection of the base compares by it #196.

Both #194 and #196 get PRs of their own.

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