Bis auf diese Warning (evtl. kann Mathias die mal anschauen) gings.
"Jac@mac-wudsn ~/jac/system/macOS/Programming/Repositories/AtariSIO/tools >make -f Makefile.posix
c++ -W -Wall -DATARISIO_DEBUG -DPOSIXVER -o adir adir.cpp DiskImage.cpp FileIO.cpp SIOTracer.cpp FileTracer.cpp Error.cpp AtrImage.cpp AtrMemoryImage.cpp DCMCodec.cpp Dos2xUtils.cpp VirtualImageObserver.cpp Directory.cpp MiscUtils.cpp MyPicoDosCode.cpp
Dos2xUtils.cpp:951:2: warning: 'sprintf' is deprecated: This function is provided for compatibility reasons only. Due to security concerns inherent in the design of sprintf(3), it is highly recommended that you use snprintf(3) instead. [-Wdeprecated-declarations]
sprintf(name, "%s%c%s", fDirectory, DIR_SEPARATOR, fOrigName[entryNum]);
^
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h:188:1: note: 'sprintf' has been explicitly marked deprecated here
__deprecated_msg("This function is provided for compatibility reasons only. Due to security concerns inherent in the design of sprintf(3), it is highly recommended that you use snprintf(3) instead.")
^
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/cdefs.h:215:48: note: expanded from macro '__deprecated_msg'
#define __deprecated_msg(_msg) __attribute__((__deprecated__(_msg)))
^
1 warning generated.
Directory.cpp:148:4: warning: 'sprintf' is deprecated: This function is provided for compatibility reasons only. Due to security concerns inherent in the design of sprintf(3), it is highly recommended that you use snprintf(3) instead. [-Wdeprecated-declarations]
sprintf(str,"%s%c%s", path, DIR_SEPARATOR, de->d_name);
^
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h:188:1: note: 'sprintf' has been explicitly marked deprecated here
__deprecated_msg("This function is provided for compatibility reasons only. Due to security concerns inherent in the design of sprintf(3), it is highly recommended that you use snprintf(3) instead.")
^
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/cdefs.h:215:48: note: expanded from macro '__deprecated_msg'
#define __deprecated_msg(_msg) __attribute__((__deprecated__(_msg)))
^
1 warning generated.
c++ -W -Wall -DATARISIO_DEBUG -DPOSIXVER -o ataricom ataricom.cpp Error.cpp AtariComMemory.cpp ComBlock.cpp FileIO.cpp
c++ -W -Wall -DATARISIO_DEBUG -DPOSIXVER -o dir2atr dir2atr.cpp DiskImage.cpp FileIO.cpp SIOTracer.cpp FileTracer.cpp Error.cpp AtrImage.cpp AtrMemoryImage.cpp DCMCodec.cpp Dos2xUtils.cpp VirtualImageObserver.cpp Directory.cpp MiscUtils.cpp MyPicoDosCode.cpp
Dos2xUtils.cpp:951:2: warning: 'sprintf' is deprecated: This function is provided for compatibility reasons only. Due to security concerns inherent in the design of sprintf(3), it is highly recommended that you use snprintf(3) instead. [-Wdeprecated-declarations]
sprintf(name, "%s%c%s", fDirectory, DIR_SEPARATOR, fOrigName[entryNum]);
^
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h:188:1: note: 'sprintf' has been explicitly marked deprecated here
__deprecated_msg("This function is provided for compatibility reasons only. Due to security concerns inherent in the design of sprintf(3), it is highly recommended that you use snprintf(3) instead.")
^
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/cdefs.h:215:48: note: expanded from macro '__deprecated_msg'
#define __deprecated_msg(_msg) __attribute__((__deprecated__(_msg)))
^
1 warning generated.
Directory.cpp:148:4: warning: 'sprintf' is deprecated: This function is provided for compatibility reasons only. Due to security concerns inherent in the design of sprintf(3), it is highly recommended that you use snprintf(3) instead. [-Wdeprecated-declarations]
sprintf(str,"%s%c%s", path, DIR_SEPARATOR, de->d_name);
^
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h:188:1: note: 'sprintf' has been explicitly marked deprecated here
__deprecated_msg("This function is provided for compatibility reasons only. Due to security concerns inherent in the design of sprintf(3), it is highly recommended that you use snprintf(3) instead.")
^
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/cdefs.h:215:48: note: expanded from macro '__deprecated_msg'
#define __deprecated_msg(_msg) __attribute__((__deprecated__(_msg)))
^
"
Und hier das Ergebnis:
Damit kann Mathias nun die Titel von "Atari Tools for Win32" auf "Atari Tools for Weltherrschaft" ändern

PS: Wäre super, wenn der Github Link auf
https://www.horus.com/~hias/atari/#tools-win32 stünde.