When an .xcconfig file contains multiple assignments of the same build setting, later assignments using using $(inherited) or $(<setting_name>) will inherit from earlier assignments in the .xcconfig. The legacy build system caused every use of $(inherited) or $(<setting_name>) skip any other values defined within the .xcconfig. To detect whether your .xcconfig is affected by this improvement, run defaults write com.apple.dt.XCBuild EnableCompatibilityWarningsForXCBuildTransition -bool YES in Terminal to cause Xcode to generate a warning about this situation. (40283621)