PiranhaObjC : Unclear usage documentation

[Samhithgb]

There seems to be a few things missing in Objective C documentation, like :

1. How do we pass piranha.properties file or list of method names corresponding to feature flags (like in PiranhaJava)?
2. What does 'FlagType' mean in the argument list?
3. Is it possible to trigger piranha for the entire project at once, instead of passing each file?

[mkr-plse]

There seems to be a few things missing in Objective C documentation, like :

1. How do we pass piranha.properties file or list of method names corresponding to feature flags (like in PiranhaJava)?

Unlike PiranhaJava and PiranhaSwift, PiranhaObjC properties are hardcoded currently. See the TODO here. The implementation has to be updated. Once #39 lands, we can take this up. Filed #51.

2. What does 'FlagType' mean in the argument list?

FlagType is used for denoting treatment, control, etc. If the flag is treated, then the treatment APIs for the flag will return true.

3. Is it possible to trigger piranha for the entire project at once, instead of passing each file?

To optimize analysis time, I recommend doing a grep for flag names to find the affected files and run PiranhaObjC on them.

[Samhithgb]

@mkr-plse Thanks for the response. I have another query actually :

• It is not clear how to get started with ObjC as well. The documentation just days run :

./piranha-objc.sh <FileName> <FlagName> <FlagType>

But I get this error when running it :

./piranha-objc.sh: line 12: ./piranha-objc/bin/clang: No such file or directory

Is there something else that needs to be run/installed to get started?

Update : I tried using ./generate-piranha-artifact.sh, but get the following error (including complete log) :

BANLSHIMPI:piranha user$ ./generate-piranha-artifact.sh

• BRANCH_SCHEME=swift-5.1-branch
• PIRANHA_VERSION=0.0.5
  ++ pwd
• PIRANHA_SRC=piranha/src
  ++ pwd
• PIRANHA_DIR=piranha/piranha-objc
  ++ pwd
• BASE_DIR=piranha
  ++ pwd
• PROCESS_DIR=piranha/process
• LLVM_PROJECT=/piranha/process/llvm-project
• LLVM_BUILDDIR=piranha/process/llvm-project/llvm/build
• DYLIB_OUTPUTDIR=piranha/process/llvm-project/llvm/build
• mkdir piranha/process
• mkdir /piranha/process/llvm-project
• cd /piranha/process
• git clone https://github.com/apple/swift.git
  Cloning into 'swift'...
  remote: Enumerating objects: 16, done.
  remote: Counting objects: 100% (16/16), done.
  remote: Compressing objects: 100% (16/16), done.
  remote: Total 1108473 (delta 7), reused 2 (delta 0), pack-reused 1108457
  Receiving objects: 100% (1108473/1108473), 568.89 MiB | 6.17 MiB/s, done.
  Resolving deltas: 10% (97879/902409)
  Resolving deltas: 10% (98641/902409)
  Resolving deltas: 100% (902409/902409), done.
  Updating files: 100% (19459/19459), done.
• ./swift/utils/update-checkout --clone --scheme swift-5.1-branch
  Skipping icu on Darwin
  Skipping cmake on Darwin
  Skipping clone of 'swift', directory already exists
  Skipping clone of 'icu', requested by user
  Skipping clone of 'cmake', requested by user
  Running obtain_additional_swift_sources with up to 8 processes.
  Traceback (most recent call last):
  File "./swift/utils/update-checkout", line 15, in
  update_checkout.main()
  File "/piranha/process/swift/utils/update_checkout/update_checkout/update_checkout.py", line 578, in main
  clone_results = obtain_all_additional_swift_sources(args, config,
  File "/piranha/process/swift/utils/update_checkout/update_checkout/update_checkout.py", line 344, in obtain_all_additional_swift_sources
  return run_parallel(
  File "/piranha/process/swift/utils/update_checkout/update_checkout/update_checkout.py", line 50, in run_parallel
  pool = Pool(processes=n_processes, initializer=init, initargs=(lk,))
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/context.py", line 119, in Pool
  return Pool(processes, initializer, initargs, maxtasksperchild,
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/pool.py", line 212, in init
  self._repopulate_pool()
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/pool.py", line 303, in _repopulate_pool
  return self._repopulate_pool_static(self._ctx, self.Process,
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/pool.py", line 326, in _repopulate_pool_static
  w.start()
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/process.py", line 121, in start
  self._popen = self._Popen(self)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/context.py", line 283, in _Popen
  return Popen(process_obj)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/popen_spawn_posix.py", line 32, in init
  super().init(process_obj)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/popen_fork.py", line 19, in init
  self._launch(process_obj)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/popen_spawn_posix.py", line 47, in _launch
  reduction.dump(process_obj, fp)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/reduction.py", line 60, in dump
  ForkingPickler(file, protocol).dump(obj)
  AttributeError: Can't pickle local object 'run_parallel..init'

BANLSHIMPI:piranha User$ ./generate-piranha-artifact.sh

• BRANCH_SCHEME=swift-5.1-branch
• PIRANHA_VERSION=0.0.5
  ++ pwd
• PIRANHA_SRC=/piranha/src
  ++ pwd
• PIRANHA_DIR=/piranha/piranha-objc
  ++ pwd
• BASE_DIR=/piranha
  ++ pwd
• PROCESS_DIR=/piranha/process
• LLVM_PROJECT=/piranha/process/llvm-project
• LLVM_BUILDDIR=/piranha/process/llvm-project/llvm/build
• DYLIB_OUTPUTDIR=/piranha/process/llvm-project/llvm/build
• mkdir /piranha/process
  mkdir: /piranha/process: File exists

[mkr-plse]

./swift/utils/update-checkout --clone --scheme swift-5.1-branch is failing and the clang plugin is not being built. Let me get back to you on this.

[Samhithgb]

Hi @mkr-plse Thanks a lot.

FYI, I was able to setup Piranha on a different machine without the above error.

Will the tool be able to parse iOS objC project files, with their imports spread across multiple packages/folders also? When trying out the tool on my project, and getting error :

(base) USER3:piranha User$ ./piranha-objc.sh FeatureManager.m feature_flag_name treatment
In file included from /Users/User/Documents/project/folder/featuremanager/FeatureManager.m:7:
/Users/User/Documents/project/folder/featuremanager/FeatureManager.h:6:9: fatal error: ‘TestHeader.h’ file not found
#import "TestHeader.h"
^~~~~~~~~~~~~~~~~~~~~

TestHeader.h is present in a different folder.

[mkr-plse]

I don't think that should affect the refactoring. Can you do two things:

1. Run test.sh as suggested here. Do the tests succeed?
2. Then can you just add some simple code (according to how feature flags are implemented in your codebase) in one of the test files and see whether it is refactoring properly?

If both the steps above are successful and if the code in your codebase (FeatureManager.m) is not being refactored, I can try to create a reproducer with an unavailable header file to debug the issue.

Also, feel free to message in the gitter channel to discuss any intermittent issues.

[Samhithgb]

@mkr-plse Thanks for the suggestions.

1. Yes the test.sh is running fine.
2. I added some code to your Treated.m, and seems to work fine as well. (The condition check is getting removed, and only log statement remains, as expected)

The issue is when I run it against my project file, the command fails with an error saying the header file is not found (as mentioned in the above comment). Is this a known issue? Please let me know. Thanks again! Will use the gitter channel for any further doubts.

[mkr-plse]

@Samhithgb Confirming that I am able to reproduce this problem. By adding a random "TestHeader.h" in one of the test files, I get a

tests/OptimisticNamed.m:19:9: fatal error: 'TestHeader.h' file not found
#import "TestHeader.h"
        ^~~~~~~~~~~~~~

I will see what can be done to address this.

[mkr-plse]

As a temporary fix, you can add the following to the piranha-objc.sh file.
-Xpreprocessor -I<path_to_header_file> after -fobjc-arc.
Let me know if this works for you.

The correct fix will be to call [SetSuppressIncludeNotFoundError](https://clang.llvm.org/doxygen/classclang_1_1Preprocessor.html#ac7bafe67fc32e41460855b39d20ff6af) from the Piranha implementation. I will file a separate issue for this.

[Samhithgb]

Hey @mkr-plse, thanks for your quick response.

Adding header file path to the script maynot be a feasible option since we are planning to have an automated flow for this.

Sure, will be waiting for the above issue resolution then. Thanks.

[mkr-plse]

Hey @mkr-plse, thanks for your quick response.

Sure, will be waiting for the above issue resolution then. Thanks.

@Samhithgb Once #67 is merged, can you verify whether you are able to run the refactoring.
You may still need to customize the exact API calls as part of the implementation.

[Samhithgb]

@mkr-plse, I am unfortunately still facing this issue after taking in the recent changes. The error message is :

/Users/samhith/Project/featuremanager/FeatureManager.h:6:9: fatal error: 'WMExchangeAccount.h' file not found
#import "WMExchangeAccount.h"

Does the current fix also consider missing header files inside another header file? Please let me know if there is any workaround I can follow to avoid this.