IIG can't find header file outside of source root folder

Number:rdar://FB9025097 Date Originated:March 1, 2021
Status:Open Resolved:
Product:Developer Tools | Xcode Product Version:12.3
Classification: Reproducible:
Building a driverkit driver using Xcode 12.3, attempting to include a header file from outside the root folder fails to build with error `file not found`. I’ve tried adding the path to Header Search Paths and tried including the header with a relative path but no luck. Furthermore, the iig tool output from Xcode doesn’t seem to show any of the header search paths added earlier to the project. This issue happens with Xcode 11.7 as well.

Please list the steps you took to reproduce the issue:
1. Create a driverkit driver project (we’re building a HIDDriverKit driver)
2. Add an external C/C++ header from outside the source directory
3. Add the path to that directory to the Header Search Paths in the project settings
4. Include the external header in the driver iig file (#include “myHeader.h”)

What did you expect to happen?
Building the project should be able to find the external header and build successfully.

What actually happened?
Xcode fails to build the project stating that it can’t find the header file.


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