Error installing UPX on Mac OS X Sequoia (15.0) on MacBook 15

[punkish (punkish)]

:info:configure ---------------------------------------------
:info:configure CMake 3.9.6, Copyright 2000-2017 Kitware, Inc. and Contributors
:info:configure C compiler on this system is: /usr/bin/clang -pipe -Os -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk -arch arm64 -std=gnu11
:info:configure ---------------------------------------------
:info:configure Error when bootstrapping CMake:
:info:configure Cannot find appropriate C++ compiler on this system.
:info:configure Please specify one using environment variable CXX.
:info:configure See cmake_bootstrap.log for compilers attempted.

This is the third program today that has errored out while installing, so I am wondering if I am actually missing something. As far as a C++ compiler is concerned, I do have gcc

gcc --version
Apple clang version 16.0.0 (clang-1600.0.26.3)
Target: arm64-apple-darwin24.0.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

MacPorts installation page says that I need xcode command line tools

Apple's Command Line Developer Tools, in case a port you're installing or one of its dependencies are not available as binaries.

I do have those as is evident below

$ xcode-select --install
xcode-select: note: Command line tools are already installed. Use "Software Update" in System Settings or the softwareupdate command line interface to install updates

Further on, the installation page says

(Optional) Apple's Xcode Developer Tools, when building some ports from source. MacPorts will let you know if this is the case.

So, my question is, is the above error MacPorts way of letting me know that I need the full Xcode Developer Tools? I had not until today and everything I threw at MacPorts worked just fine. But starting today, I am facing these messages. The only difference -- now I have upgraded to Mac OS X Sequoia

[punkish (punkish)]

I downloaded the latest MacPort pkg again, reinstalled it, and ran sudo port -v selfupdate and got the following message

Welcome to the RSYNC daemon on ftp.fau.de.
Not all of our mirrors are available through rsync.


receiving file list ... done
./

sent 74 bytes  received 98 bytes  114.67 bytes/sec
total size is 35371530  speedup is 205648.43
Creating port index in /opt/local/var/macports/sources/rsync.macports.org/macports/release/tarballs/ports
Warning: All compilers are either blacklisted or unavailable; defaulting to first fallback option
Failed to parse file R/R-pbdMPI/Portfile: can't read "mpi_port": no such variable
Failed to parse file lang/rust-bootstrap/Portfile: rust_build.version (1.77.0) must be newer than rust_build.stage0_versions (1.80.1 1.80.0)

Total number of ports parsed:	2
Ports successfully parsed:	0
Ports failed:			2
Up-to-date ports skipped:	39668


The ports tree has been updated.
All installed ports are up to date.

So, what does "Warning: All compilers are either blacklisted or unavailable; defaulting to first fallback option" mean and what do I have to do to correct this?