[swift-evolution] Proposal: Initialization should not be required in precondition(false) case.
clattner at apple.com
Fri Feb 12 11:32:24 CST 2016
On Feb 12, 2016, at 9:27 AM, Amir Michail <a.michail at me.com> wrote:
>>> What’s wrong with having the compiler explicitly check for “false”?
>> Weird special cases make the compiler less predictable.
> True, but not having them requires deeper knowledge of the standard libraries.
> In practice, just checking for “false” would solve this problem.
That is not what you’re actually proposing. You are proposing that the compiler encode special knowledge of the precondition *library function* into the compiler, and teach it about a single special case. We don’t like the compiler to have special cases like this for a large number of reasons, in particular, if we did this, someone would file a bug asking for *their* equivalent reimplementation of precondition to have the same magic blessed behavior.
This is a slippery slope that leads to a lot of complexity downstream, it is better to keep the compiler simple and predictable. Also, as other people have pointed out, this has already been solved for you: just use preconditionFailure.
More information about the swift-evolution