allows ref struct is inherited implicitly, so restating it on an override is
CS0460 even alongside a legal disambiguator. Roslyn still re-emits the byreflike
flag on the override's own type parameter, and the general constraint printer
turns that flag back into source, so the disambiguator stays legal only as long
as it is built separately. Cover a C# 13 base whose annotated and plain methods
both allow ref structs.
Assisted-by: Copilot:claude-opus-5:GitHub Copilot CLI
Sebastien Lebreton