Hello,
I am working on these ideas you mentioned before recently.
I have some questions for these because I couldn't find some commands or detailed instructions.
- Can you make sense of the code? (The stdlib is written in a somewhat unusual Swift dialect, and it may take some getting used to. It deals a lot with low-level builtins and even some language-level constructs that don't typically occur in regular Swift development. Not to mention gyb!)
The code makes sense for me. I couldn't get some, but I understood it to google it. 
I'd like to make sure the directory.
I need to work on swift/stdlib/public/ and test/stdlib, right?
I don't need to look at swift/stdlib/ except for swift/stdlib/public/, right?
- Try running the test suite; can you figure out where/how it is implemented? Find and look through the tests we run for collection types. Is it easy to make sense of them? Think about how a new Collection type like a deque could be integrated into the existing tests. What tests can we reuse? What new tests will we need to add?
I run utils/build-script -Rt, but I think it's a wrong command to test stdlib test suits.
What command am I supposed to use to test test/stdlib?
I'm confused how to check test suits. I read https://github.com/apple/swift/blob/master/docs/Testing.md, but it is ambiguous for me.
- Select some stdlib algorithm and find its benchmark(s). Try to optimize the algorithm by tweaking its code, and see if it improves benchmark results. (Submit a PR if so!) If you don't find benchmarks for the algorithm you selected, try writing a PR to add one.
I run utils/build-script -RtB.
Is it correct to find its benchmark?
Could you tell me the process how you implement and debug swift stdlib, please?
That would be helpful to implement quickly.
As I asked you before, Swift compile error - #5 by Gumichocopengin8, could run utils/build-script --debug --Xcode but still I cannot run utils/build-script --debug. Compiler says error: 'futimens' is only available on macOS 10.13 or newer [-Werror,-Wunguarded-availability-new], but my macOS version is the latest. Are there any problems?
I'm sorry to ask a lot of questions.
Thank you.