Now that allocator.resize() is allowed to fail, programs may wish to
test code paths that handle resize() failure. The simplest way to do
this now is to replace the vtable of the testing allocator with one
that uses Allocator.noResize for the 'resize' function pointer.
An alternative way to support this testing capability is to augment the
FailingAllocator (which is already useful for testing allocation failure
scenarios) to intentionally fail on calls to resize(). To do this, add a
'resize_fail_index' parameter to the FailingAllocator that causes
resize() to fail after the given number of calls.
* std.unicode: Add more UTF-16 decoding functions
This mostly makes parts of Utf16LeIterator reusable
* std.json: Fix decoding of UTF-16 surrogate pairs
Before this commit, there were 524,288 codepoints that would get decoded improperly. After this commit, there are 0.
Fixes#16828
