Commands
./ddct generate-all
./ddct build ldc 1.38.0
./ddct build dmd 2.107.1
system gcc → build ldc lts ← custom llvm 7
↓
system gcc → build ldc 1.20 ← custom llvm 10
↓
system gcc → build ldc stable ← custom llvm 15+
↓
system gcc → build ldc stable (again?) ← custom llvm 15+
↓
system gcc → build any other compilers