Recently I've been seeing this on 10.5 (both x86 and ppc):
MacXS:~ fw$ sudo port upgrade outdated
Warning: No port clang-9.0 found in the index.
Warning: No port llvm-3.7 found in the index.
Warning: No port libcxx found in the index.
Warning: No port clang_select found in the index.
Warning: No port ld64 found in the index.
Warning: No port perl5 found in the index.
I thought the libc++ change in 2.6 wasn't being applied to 10.5, but the
problem seems to be roughly coincident with the new base. Perhaps the
index generator script was updated incorrectly?
Fred Wright