id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	blockedby	blocking	notify_on_close	platform	project
4923	macOS build problems on Big Sur caused by wheel file names	Tom Goddard	Tom Goddard	"On macOS Big Sur, 11.x, the ChimeraX build fails because bundle wheel file names have suffix -macosx_11_0_x86_64.whl and pip won't install that wheel saying it is an unknown platform, and wants suffix -macosx_10_16_x86_64.whl.  This is because Python considers the macOS version to be 10.16 as reported by import platform ; platform.mac_ver() instead of 11.4.  Online posts say that is because 

""Applications compiled for Big Sur get back ""11.0"" as the operating system version.  Applications compiled for earlier versions get ""10.16"". This is so logic that assumes 10 as the prefix will not break.""

https://stackoverflow.com/questions/65290242/pythons-platform-mac-ver-reports-incorrect-macos-version/65402241

We are using the standard Python 3.9.6 binary distribution compiled for macOS 10.9 I think so it reports 10.16.  To work around this problem ChimeraX can be compiled on Big Sur setting environment variable SYSTEM_VERSION_COMPAT=1

env SYSTEM_VERSION_COMPAT=1 make build-from-scratch

This causes macOS to always report the macOS version as 10.16 and the ChimeraX build then makes all wheels with suffix -maxosx_10_16_x86_64.whl and these install without problems.

The ChimeraX core wheel file name uses the 10_16 suffix because it determines the wheel file name using mk/os.make (variable BIN_PLATFORM) and our Makefile explicitly uses 10_16 for macOS versions >10.

I think it would be more sensible to have ChimeraX produce wheel file names with 11_0 in the suffix and for the next macOS Monterey (12.0) use 12_0."	defect	closed	moderate		Platform		fixed		Eric Pettersen Greg Couch z.pearson9@…				all	ChimeraX