Hi,

This patch merges the D front-end implementation with dmd upstream e2fe2687b.

Backports VRP fixes from the D front-end implementation to the C++
port, and  fixes errors reported by ubsan build where the conversion
from D didn't include adjusting integer suffixes from 'UL' to 'ULL',
fixing https://gcc.gnu.org/PR88366.

Bootstrapped and tested on x86_64-linux-gnu --with-build-config=bootstrap-ubsan

Committed to trunk as r266925.

-- 
Iain

---