Protobuf CocoaPod depends upon umbrella header ordering

[paulb777]

CocoaPods will fail to build the Protobuf CocoaPod if the explicitly pathed headers are ordered before the wild carded headers in the generated umbrella header file.

This is exposed in the unreleased CocoaPods master branch. CocoaPods may change back to the old behavior, but it would probably be good to make the Protobuf CocoaPod less fragile.

Details and example at CocoaPods/CocoaPods#7518.

[paulb777]

Part of the problem seems to be a circular dependency chain between Any.pbobjc.h and GPBWellKnownTypes.h. Other strange things are GPBProtocolBuffers.h being kind of a duplicate umbrella header and header sequencing to test the protoc versioning.

[thomasvl]

This sounds a little like #4301, is it the same thing?

From a quick look at the linked issue, that seems to say it is an ordering problem, but it isn't clear that protos has and ordering problem vs. something causing the imports to be found via different paths, so the #import doesn't collapse into a single definition?

[paulb777]

It's similar to #4301, triggered by a different cause, with likely the same solution.

In this case, because the pre-release version of CocoaPods generated the umbrella header with a different order, the Protobuf module failed to be created during the build because of the order requirements.

The CocoaPods team decided that even though relying upon header order is not technically correct, that it wasn't an acceptable change for a minor CocoaPods release update and decided to maintain the requested order with CocoaPods/CocoaPods#7539 that got in before the first 1.5.0 beta went out.

So there is not a near term CocoaPods risk.

To reproduce :

• install from CocoaPods normally
• open Pods/Target Support Files/Protobuf/Protobuf-umbrella.h
• move the "Any.pbobjc.h" through "Wrappers.pbobjc.h" in front of the other headers
• build

[thomasvl]

Other strange things are GPBProtocolBuffers.h being kind of a duplicate umbrella header

I'm not sure how to resolve this one. Cocoapods isn't the only packaging system, we need to provide an umbrella for others (Carthage, direct source usage, etc).

header sequencing to test the protoc versioning

Not sure I follow this one, this should just mean the defines have to exist before we import other headers, no?

[paulb777]

If you create your own module_map with your own umbrella header - https://guides.cocoapods.org/syntax/podspec.html#module_map, then CocoaPods shouldn't generate one.