As of Xcode 15.4 (and possibly earlier), Xcode does does not build all architectures for a target when 'Build Active Architecture Only' (ONLY_ACTIVE_ARCH) is set to 'No'. Instead, the run destination ('My Mac' vs 'Any Mac') appears to completely override that setting. The help documentation blurb for ONLY_ACTIVE_ARCH states the run destination is only used when the build setting is enabled, and that was indeed the case in earlier versions of Xcode. Has the expected behaviour of that setting changed?

I have a command line tool that zsh refuses to run when built for Apple Silicon or as a univerisal binary (the specific message is zsh: killed TOOL_NAME). I can only get it to run if I build it exclusively for Intel/Rosetta. Running/debugging from within Xcode works fine for any architecture. The tool is a very simple C/C++ unix command-line tool; it doesn't have any external dependencies beyond the C runtime and the C++ STL. I suspect something in code signing is going awry, but I've tried various team and certificate combinations without any luck. I've also tried enabling/disabling the app sandbox, also without any luck. (The app is not for distribution so it doesn't really need to be code signed at all.) Any suggestions?