assert() and fatalError()
These functions are meant to be used in user code. They are enabled in debug
mode and disabled in release or fast mode.
_precondition() and _preconditionFailure()
These functions are meant to be used in library code to check preconditions at
the api boundry. They are enabled in debug mode (with a verbose message) and
release mode (trap). In fast mode they are disabled.
_debugPrecondition() and _debugPreconditionFailure()
These functions are meant to be used in library code to check preconditions that
are not neccesarily comprehensive for safety (UnsafePointer can be null or an
invalid pointer but we can't check both). They are enabled only in debug mode.
_sanityCheck() and _fatalError()
These are meant to be used for internal consistency checks. They are only
enabled when the library is build with -DSWIFT_STDLIB_INTERNAL_CHECKS=ON.
I modified the code in the standard library to the best of my judgement.
rdar://16477198
Swift SVN r18212
Before this commit, RandomAccessIndex was a refinement of
NumericOperations, which forced it to support inappropriate operations
such as multiplication. Many obvious random-access index types can't
support multiplication (e.g. a StridedIndex adapter, which moves its
underlying index by N positions for each increment).
Along the way:
* the addition and subtraction operations on RandomAccessIndex were
renamed to advancedBy and distanceTo, which prevents nasty ambiguities
when a type conforms to both RandomAccessIndex and Integer, and allows
Index DistanceTypes to actually be signed integers even when the Index
is unsigned.
* Before this commit, using internal interfaces, it was possible to
request static checking without also getting dynamic checks when
static checking is impossible. Now the relationship between static
and dynamic checking is built into the core protocols.
* NumericOperations.swift was moved into IntegerArithmetic.swift.gyb,
correcting missing operators by generating them programmatically and
in preparation for renaming the protocol to something more appropriate
Fixes
<rdar://problem/16246927> RandomAccessIndex is over-constrained
and possibly:
<rdar://problem/15605729> Make all operators generic over
protocols (in particular, get NumericOperations done)
Swift SVN r14854
