Modifying IBDesignable causes entire Swift project to recompile.

Number:rdar://20690594 Date Originated:4-24-2015
Status:Open Resolved:
Product:Developer Tools Product Version:Xcode 6.3.1
Classification: Reproducible:
We are unable to take advantage of the awesome features of IBDesignable in our project because any changes made to these files causes the entire project to get recompiled (incremental compilation is effectively not working). Also IBDesignable slows down Xcode a lot too, and slows down the build in other ways it seems.

Steps to Reproduce:
Create a class with @IBDesignable.

Make changes to this class, and build. 

Expected Results:
Only the files that use this class are recompiled.

Actual Results:
All swift files in the project will get compiled again. 

XCode 6.3.1 and OSX 10.10.3





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