Walks the inference algorithm of the standard (draft-v11, 12.6.3) and
adds a test per rule that the revived NRefactory suite did not already
exercise: exact inference for ref parameters and its non-applicability
of the base-type walk, explicit lambda parameter types, exact/upper
bound inference through arrays, nullables and variance nesting, the
unique-base-type restriction, value-type elements forcing exact
inference, conflicting exact bounds, and best common type.
Two rules are pinned as ignored tests because the implementation does
not follow the standard yet: a value argument to an 'in' parameter
infers no bound (12.6.3.7 wants a lower-bound inference), and tuple
literals are not inferred elementwise (12.6.3.7/12.6.3.8). Both tests
assert the csc-verified result and should go green when the rules are
implemented.
Nullable unwrapping in exact and upper-bound inferences needs no
dedicated code path in this implementation: T? is represented as the
constructed type Nullable<T>, so the constructed-type case already
produces the elementwise exact inference the standard asks for; the
new tests pin that equivalence. Function-pointer inference rules and
the explicit-return-type inference of 12.6.3.15 remain untested: the
former needs a MetadataModule to construct FunctionPointerType, the
latter is not representable in LambdaResolveResult.
Assisted-by: Claude:claude-fable-5:Claude Code
Siegfried Pammer
132b33e530