The layouts of resilient value types shipped in the Swift 5 standard library
x and overlays will forever be frozen in time for backward deployment to old
Objective-C runtimes. This PR ensures that even if the layouts of these types
evolve in the future, binaries built to run on the old runtime will continue
to lay out class instances in a manner compatible with Swift 5.
Fixes <rdar://problem/45646886>.
Swift uses rt_swift_* functions to call the Swift runtime without using dyld's stubs. These functions are renamed to swift_rt_* to reduce namespace pollution.
rdar://28706212
Most tests were using %swift or similar substitutions, which did not
include the target triple and SDK. The driver was defaulting to the
host OS. Thus, we could not run the tests when the standard library was
not built for OS X.
Swift SVN r24504
The allocator's crimes include:
* It uses OS SPI that must not be used by non-OS apps.
* It does not play well with memory debugging tools like Instruments.
* It does not return memory to the OS in response to memory pressure.
* It is less tested than we would like because many configurations
inadvertently turn it off (such as running from Xcode).
* Its per-thread magazine implementation does not actually work.
* Its "try alloc" flag is incompletely implemented and never used.
* Its "zero fill" flag is unimplemented and inconsistently used.
Swift SVN r20757
