Audit the conversion test suites against the conversions chapter of the
draft-v8 C# standard and add tests for every rule that had none:
exhaustive implicit/explicit numeric conversion matrix, tuple/ValueTuple
and nullable-annotation identity, interpolated-string / throw-expression /
tuple-literal conversions, the boxing rule set including variance-based
boxing and unboxing, delegate-to-System.Delegate and IReadOnlyList<T>
reference conversions, type-parameter variance and effective-base-class
casts, generic method groups (inference, explicit type arguments, no
inference from the return type), the anonymous-function compatibility
checks CSharpConversions performs itself (via a LambdaResolveResult test
double), standard-conversion exclusion of user-defined operators, and
operators declared in base classes of the source type.
Two rules are implementation gaps rather than test gaps and get ignored
placeholder tests naming the gap: default literal conversions (10.2.16)
are an explicit TODO in CSharpConversions, and switch expressions
(10.2.18) have no ResolveResult representation. The full
section-by-section map is in
Analyses/ILSpy/2026-07-24_conversions-spec-coverage.md.
Assisted-by: Claude:claude-fable-5:Claude Code
Siegfried Pammer
787cc71b3a