Revert "Fix #1176 JSON Decoder and Encoder limit disagreement (#1242)"

[jmschonfeld]

In addition to the known issue where this new test crashes on Windows, I've also found that the test crashes on non-macOS Apple platforms (confirmed a crash on iOS, tvOS, and watchOS which CI does not test on this repo). In those cases, the test is crashing because we're hitting the stack guard in a deeply nested call - I think this test ends up hitting the stack limit. For some reason it doesn't seem to occur on macOS or Linux as reported in the original PR (and I confirmed it passed on macOS) so perhaps there's a difference in the stack limits between these environments.

Noting that while the test passes on macOS + Linux it fails on all other platforms, I'm posting this revert to roll back the change until we can further investigate a better way to test this code path that avoids hitting the stack guard.

cc @jevonmao

[jmschonfeld]

@swift-ci please test

[jmschonfeld]

I dug a bit deeper to see if I could resolve this quickly rather than reverting, and found out:

• iOS/tvOS/watchOS and Windows platforms have a significantly smaller default stack size than Linux and macOS (Linux/macOS default to around 8mb whereas iOS/tvOS/watchOS/Windows default to around 1MB). I believe this is why the pass test is crashing on those platforms - a recursion limit of 512 is too high to prevent hitting the stack guard. We likely need to adjust the recursion limit on a per-platform basis to allow 512 on macOS/Linux (to reduce any compatibility fallout) but lower to something like 256 on platforms with smaller default stack sizes
• After attempting to perform the above mitigation myself and creating a new pass test that contains 400 nested arrays rather than 512, the pass test still crashes on those platforms. In fact, setting the recursion limit to just 5 still allows the pass test to crash when the input data has 400 nested arrays. It seemed to decode successfully, but hit the stack guard on iOS while re-encoding it. It seems that 400 might be too high of a recursion limit, however the bigger problem here is that the recursion limit doesn't seem to be respected during encoding (but a cursory glance at the code seems to suggest perhaps it should be). I'm going to revert this for now and will add more information to Windows/iOS Crash During Deep JSON Encoding/Decoding #1304 to track this issue so that it can be resolved before re-merging the original change