38963247: Spurious clang warning about non-portable path with case-sensitive symlink

[openradar-mirror]

Description

Summary:

When importing symlinked header files, clang sometimes seems to compare the imported path to the symlink target, rather than to the path of the symlink itself. It may then issue a spurious warning about a mismatch between the cases of the two paths, like this one:

Non-portable path to file '<protobuf/Any.pbobjc.h>'; specified path differs in case from file name on disk

There is additional discussion in protocolbuffers/protobuf#3218. We have not been able to reproduce the issue with a simpler project than the attached, and suspect there is something in addition to the case mismatch necessary to trigger the warning.

Steps to Reproduce:

1. Download and unzip the attached TestApp project
2. Run pod install from the unzipped directory and open TestApp.xcworkspace
3. Build the app for the iPhone X simulator

Expected Results:

The app builds without any warnings.

Actual Results:

The app builds with thirteen warnings similar to the one described above.

Version/Build:

macOS 10.13.3 (17D102)
Xcode 9.2 (9C40b)
CocoaPods 1.4.0

Attachments:

https://github.com/google/protobuf/files/1854645/TestApp.Swift.with.Firestore.zip

Product Version:
Created: 2018-03-28T18:00:45.217980
Originated: 2018-03-28T00:00:00
Open Radar Link: http://www.openradar.me/38963247