[PATCH] c++: Adjust constexpr covariant call results [PR126324]

[Odysseas Georgoudis]

This patch adjusts successful scalar virtual-call results to the static
call type after caching the underlying function result.  The cache
therefore retains the final overrider's declared result type for direct
calls.

Tested on x86_64-pc-linux-gnu with:

  g++.dg/cpp2a/pr126324.C
  g++.dg/cpp2a/constexpr*.C
  g++.dg/cpp2a/consteval*.C

Thanks,
Odysseas

PR126324.patch
Description: PR126324.patch