[swift-evolution] Change default compiler fix for not-unwrapped Optional from ! To ?

Rod Brown rodney.brown6 at icloud.com
Fri Jul 14 01:05:28 CDT 2017

> On 14 Jul 2017, at 2:36 pm, Robert Bennett via swift-evolution <swift-evolution at swift.org> wrote:
> When writing Swift code, it is not uncommon to forget to unwrap optionals. The compiler will offer a fixit, telling you you must insert either a ? or a !. However, when you accept the fixit, ! is inserted (at least, it is for me in Xcode 8.3).
When you treat an optional as non-optional, the compiler has no way to do a fixit that would appropriately handle the optional. Felix made a good example. The only direct fixit would be a force unwrap. If you used “?” then your non-optional use would turn into an optional and your parameter would generally be non-optional. The fixit is just explicitly doing what you implicitly expected it to do.

> Ideally the fixit would default to ? because this is the preferred option; ! is often a sign of non-Swifty code and does not interact well with idiomatic Swift constructs such as if-let-(as?), guard-let-(as?)-else, etc. Also I think it’s safe to say that fixits should not err on the side of crashing at runtime.

" ! is often a sign of non-Swifty code “
I would strongly challenge this assumption. Many core team members have commented about appropriate uses of the ! operator. It shouldn’t be used lightly, but it’s there for a reason and it most definitely isn’t “non-swifty”.

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