M1 MacOS error: sma.cpp:28:10: fatal error: 'iostream' file not found

[rmkc23]

➜ ~ brew reinstall rfidresearchgroup/proxmark3/proxmark3
==> Fetching rfidresearchgroup/proxmark3/proxmark3
==> Downloading https://github.com/RfidResearchGroup/proxmark3/archive/refs/tags
Already downloaded: /Users/rmkc/Library/Caches/Homebrew/downloads/64ce14378fc2ca25c6b25ba79584ab3835649383e8f379f9c44bf79e8fc3df28--proxmark3-4.19552.tar.gz
==> Reinstalling rfidresearchgroup/proxmark3/proxmark3
==> make clean
==> make all BREW_PREFIX=/opt/homebrew PLATFORM=PM3RDV4 SKIPQT=1
Last 15 lines from /Users/rmkc/Library/Logs/Homebrew/proxmark3/02.make:
[=] CXX mfd_multi_brute
[*] MAKE cryptorf/all
[-] CC cm.c
[-] CC ../../common/cryptorf/cryptolib.c
[-] CC util.c
[=] CXX cm
[-] CC sm.c
[=] CXX sm
[-] CXX sma.cpp
sma.cpp:28:10: fatal error: 'iostream' file not found
28 | #include
| ^~~~~~~~~~
1 error generated.
make[1]: *** [obj/sma.o] Error 1
make: *** [cryptorf/all] Error 2

The iostream file is located within the homebrew install of LLVM at:
/opt/homebrew/Cellar/llvm/19.1.6/include/c++/v1/iostream

ChatGPT suggested setting several environment variables, but to no avail:

brew link --force llvm
export CC=/opt/homebrew/opt/llvm/bin/clang
export CXX=/opt/homebrew/opt/llvm/bin/clang++
export CPLUS_INCLUDE_PATH=/opt/homebrew/opt/llvm/include/c++/v1
export LIBRARY_PATH=/opt/homebrew/opt/llvm/lib
export CPATH=/opt/homebrew/opt/llvm/include
export LDFLAGS="-L/opt/homebrew/opt/llvm/lib"
export CPPFLAGS="-I/opt/homebrew/opt/llvm/include"

I have successfully installed proxmark3 (and updated the generic device and it runs ok) on an Intel iMac 2015 running OS11.7.10 (Big Sur), and on Ubuntu running on the M1 under VMWare. The failed install is on a MacBook Pro 14" M1 MacOS 15.2 (Sequoia, latest) with Xcode 16.2 and Homebrew 4.4.12.