Roslyn passes a display class into a local function by ref, and a local
function that only forwards that parameter to a sibling has no closure
variable of its own. The closure analysis therefore found nothing to
anchor it and fell back to the root method body, which put it out of
reach of the callees it forwards to; CallBuilder then hit the assert
guarding a local function reference it cannot resolve and emitted the
raw metadata name of the target instead.
The constructor path also mixed use-site containers into a scope the
closure analysis had already determined; when the use-sites live in
separate function bodies there is no common container, and resetting to
the constructor body threw that scope away.
Assisted-by: Claude:claude-opus-5:Claude Code
Siegfried Pammer