Is this with optimization?

Comment by markus sähn (JIRA)

no optimization.

Since NSCalendar is a bridged CF type it may be a failure in the ref counting from the bridge itself.

I added a unit test (currently disabled); this only exhibits on linux builds -
Process 41490 stopped

• thread Fixing whitespace formatting #1: tid = 41490, 0x00007ffff7b0ad0f libswiftCore.so, name = 'TestFoundation', stop reason = signal SIGTRAP
  frame #0: 0x00007ffff7b0ad0f libswiftCore.so
  -> 0x7ffff7b0ad0f: nop
  (lldb) bt

• thread Fixing whitespace formatting #1: tid = 41490, 0x00007ffff7b0ad0f libswiftCore.so, name = 'TestFoundation', stop reason = signal SIGTRAP

• frame #0: 0x00007ffff7b0ad0f libswiftCore.so
  frame Fixing whitespace formatting #1: 0x00007ffff731fae5 libFoundation.so`NSCalendar.AMSymbol.getter(self=0x000000000083cce0) + 213 at NSCalendar.swift:280
  frame Fixing grammar issue #2: 0x000000000041904b TestFoundation`TestNSCalendar.test_currentCalendarRRstability(self=0x00000000007e31a0) -> () + 155 at TestNSCalendar.swift:85
  frame Syntax highlighting in README.md #3: 0x000000000041969a TestFoundation`partial apply + 26 at TestNSCalendar.swift:0
  frame Add @noescape to Synchronous Enumeration, Predicate, and Comparator Blocks #4: 0x0000000000412711 TestFoundation`thunk + 17 at TestNSRunLoop.swift:0
  frame Verify contents of the file attributes dictionary #5: 0x00000000004163c1 TestFoundation`partial apply for thunk + 81 at TestNSCalendar.swift:0
  frame Fix URL in README.md #6: 0x00007ffff6d382ee libXCTest.so`ext.XCTest.XCTest.XCTestCase.invokeTest () -> () + 6014
  frame Use Correct Source Index in NSArray.getObjects #7: 0x00007ffff6d35ee8 libXCTest.so`XCTest.XCTMain (Swift.Array<XCTest.XCTestCase>) -> () + 328
  frame [WIP] Implement NSRangeFromString #8: 0x0000000000412229 TestFoundation`main + 1897 at main.swift:61
  frame Use Array.reserveCapacity in NSArray/NSMutableArray #9: 0x00007ffff5b47ec5 libc.so.6`__libc_start_main(main=(TestFoundation`main at main.swift), argc=1, argv=0x00007fffffffe478, init=<unavailable>, fini=<unavailable>, rtld_fini=<unavailable>, stack_end=0x00007fffffffe468) + 245 at libc-start.c:287
  frame Fix download link #10: 0x00000000004119f9 TestFoundation
  (lldb) up
  frame Fixing whitespace formatting #1: 0x00007ffff731fae5 libFoundation.so`NSCalendar.AMSymbol.getter(self=0x000000000083cce0) + 213 at NSCalendar.swift:280
  277 }
  278
  279 public var AMSymbol: String {
  -> 280 return _symbol(kCFDateFormatterAMSymbolKey)
  281 }
  282
  283 public var PMSymbol: String {
  (lldb) p self
  (Foundation.NSCalendar) $R0 = 0x000000000083cce0 {
  Foundation.NSObject = {}
  _base = (info = 8832, pad = 0)
  identifier = 0x00007ffff77da138 libFoundation.so`_kCFCalendarIdentifierGregorian
  _locale = 0x0000000000000000
  _localeID = 0x00007ffff77d2398 libFoundation.so`_CFLocaleCopyCurrentGuts.str
  _tz = 0x00000000007f1040 -> 0x00007ffff77cd238 full type metadata for Foundation.NSTimeZone + 16
  _cal = 0x0000000000000000
  }
  (lldb) po self
  <NSCalendar: 0x83cce0>

Comment by Collin Hundley (JIRA)

This is an old issue, but I'm experiencing the exact same problem on Swift 3 snapshot 08-23. Was this issue ever resolved?

The calendar releasing issue was fixed in SR-2879.

The unit test that Philippe added uncovered a different bug that was resolved in #1472