Cmake-boostrap is not finding proper compiler on system -> LLVM Clang cmake failind to build

[Behinder (behinder)]

Trying to build cmake I encountered lot of errors as the compiler was not able to find includes. I used ​https://cmichel.io/fixing-cpp-compilation-bugs-for-the-mac-os-catalina-upgrade/ trying to solve the problem and I added necessary paths however without llvm because I don't have it installed yet and I cannot install it because cmake build is failing.

I am attaching debug.log for reference. Key parts are IMO:

cmake-bootstrap has no conflicts
DEBUG: Executing org.macports.main (cmake-bootstrap)
DEBUG: dropping privileges: euid changed to 502, egid changed to 501.
DEBUG: Privilege de-escalation not attempted as not running as root.
DEBUG: archivefetch phase started at Tue Oct  8 15:29:52 CEST 2024

how can I run something not as root if I did sudo? Misleading.. AND

CMake 3.9.6, Copyright 2000-2017 Kitware, Inc. and Contributors
C compiler on this system is: /usr/bin/clang -pipe -Os -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX14.sdk -arch arm64 -std=gnu11
---------------------------------------------
Error when bootstrapping CMake:
Cannot find appropriate C++ compiler on this system.
Please specify one using environment variable CXX.
See cmake_bootstrap.log for compilers attempted.

How can it not find proper C++ compiler on this system if in the log variable is set CXX='/usr/bin/clang++'

and clang++ --version gives:

/usr/bin/clang++ --version
Apple clang version 15.0.0 (clang-1500.3.9.4)
Target: arm64-apple-darwin23.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

I set up MacPorts to always compile from source everything. And I was able to install few packages without problems. Here the list:

  apr @1.7.4_0 (active)
  argon2 @20190702_1 (active)
  autoconf @2.72_0 (active)
  automake @1.17_0 (active)
  bison @3.8.2_2 (active)
  bison-runtime @3.8.2_0 (active)
  bzip2 @1.0.8_0 (active)
  cctools @949.0.1_3+xcode (active)
  clang_select @2.4_0 (active)
  curl-ca-bundle @8.10.1_0 (active)
  expat @2.6.3_0 (active)
  fzf @0.55.0_0 (active)
  gdbm @1.24_0 (active)
  gettext @0.22.5_0 (active)
  gettext-runtime @0.22.5_0 (active)
  gettext-tools-libs @0.22.5_0 (active)
  go @1.23.1_0
  go @1.23.2_0 (active)
  gperf @3.1_0 (active)
  ld64 @3_6+ld64_xcode (active)
  ld64-xcode @2_6 (active)
  libcxx @5.0.1_5 (active)
  libedit @20240808-3.1_0 (active)
  libffi @3.4.6_1 (active)
  libiconv @1.17_0 (active)
  libtextstyle @0.22.5_0 (active)
  libtool @2.4.7_4
  libtool @2.5.3_0 (active)
  llvm_select @2_1 (active)
  lzo2 @2.10_0 (active)
  m4 @1.4.19_1 (active)
  mhash @0.9.9.9_1 (active)
  nasm @2.16.03_0 (active)
  ncurses @6.5_0 (active)
  nghttp2 @1.63.0_0 (active)
  openssl @3_20 (active)
  openssl3 @3.3.2_0 (active)
  pcre2 @10.44_0 (active)
  php_select @1.0_1 (active)
  pkgconfig @0.29.2_0 (active)
  python3_select @0.1_0 (active)
  python3_select-312 @0.1_1 (active)
  python312 @3.12.6_0+lto+optimizations
  python312 @3.12.7_0+lto+optimizations (active)
  python_select @0.3_10 (active)
  python_select-312 @0.3_1 (active)
  readline @8.2.013_0 (active)
  sqlite3 @3.46.1_0 (active)
  vim @9.1.0000_0+huge (active)
  x264 @20191217_0 (active)
  xz @5.4.7_0 (active)
  zlib @1.3.1_0 (active)
  zsh @5.9_3 (active

[jmroot (Joshua Root)]

Please also attach the cmake_bootstrap.log.

[ryandesign (Ryan Carsten Schmidt)]

The log shows you have command line tools 16 so this sounds like #70750. Try the solution at ProblemHotlist#clts16.