json test_read_{list,object}_streaming are flaky on 32-bit

[alexcrichton]

These tests have been seen to be flaky on 32-bit with a very obscure error:

---- json::tests::test_read_object_streaming stdout ----
    task 'json::tests::test_read_object_streaming' failed at 'assertion failed: `(left == right) && (right == left)` (left: `BooleanValue(true)`, right: `BooleanValue(true)`)', C:\bot\slave\auto-win-32-opt\build\src\libserialize\json.rs:3062

---- json::tests::test_read_list_streaming stdout ----
    task 'json::tests::test_read_list_streaming' failed at 'assertion failed: `(left == right) && (right == left)` (left: `BooleanValue(true)`, right: `BooleanValue(true)`)', C:\bot\slave\auto-win-32-opt\build\src\libserialize\json.rs:3062 

I find these error messages curious. These tests only fail on windows, and they only fail with optimization turned on. I suspect an LLVM bug here, but I haven't confirmed it. For now I'm going to ignore these tests on windows.

[klutzy]

From #14083 (auto-linux-32-nopt-t failure log), it may be flaky on other 32-bit machines.

[alexcrichton]

Ah yes, sorry, I meant to update this bug. I have noticed and reproduced this on 32-bit platforms in general.

[frewsxcv]

visiting for triage

Can confirm these tests are still ignored:

• rust/src/libserialize/json.rs

  Line 3602 in eaf4c5c

  #[cfg_attr(target_pointer_width = "32", ignore)] // FIXME(#14064)

• rust/src/libserialize/json.rs

  Line 3641 in eaf4c5c

  #[cfg_attr(target_pointer_width = "32", ignore)] // FIXME(#14064)

• rust/src/libserialize/json.rs

  Line 3725 in eaf4c5c

  #[cfg_attr(target_pointer_width = "32", ignore)] // FIXME(#14064)

I unfortunately don't have a 32 bit window machine to test them on though :(

[steveklabnik]

Triage: same as @frewsxcv , These are still presently ignored, but I don't have the proper machinery.

@alexcrichton , should we maybe try removing the ignore, and letting bors take a look? If it was a bug in LLVM, well, a lot has changed since 2014....