Turn off SWIFT_ENABLE_REFLECTION on the stdlib_minimal preset

[kubamracek]

No description provided.

[kubamracek]

@swift-ci please test

[yln]

Would it be possible to only #if-else the @availability annotation instead of duplicating all of the Mirror declarations here?

[yln]

The patch makes sense to me, but I was a bit disheartened by the sheer number of #if SWIFT_ENABLE_REFLECTION directives needed (77 files touched).

Would it be possible to leave Mirror declarations and uses intact, but "compile out" its implementation and return dummy values or crash. Similarly to what we do here for String.

[kubamracek]

Not sure what you're actually proposing. I think the @available attribute is required here, otherwise your code still compiles. I need to make let m = Mirror(x) not compile. Given that we can't #ifdef-out only the attribute, I'm not sure how else can I do this?

[mikeash]

Could we use availability macros for this? -define-availability 'SwiftReflection *' normally, and -define-availability 'SwiftReflection unavailable' when this stuff is turned off, then annotate everything with @available(SwiftReflection). I'm not entirely sure that availability macros actually work this way....

[kubamracek]

Very cool idea, though I don't think -define-availability lets us specify either "*" or "unavailable", I think it today only accepts specific platform names/versions:

-define-availability argument:1:18: error: expected version number
Dummy:unavailable
                 ^

[mikeash]

Well nuts. I wonder if it would be worth extending this feature to work here, or otherwise modifying @available or #if so that we can accomplish this.

[mikeash]

It would be interesting to see if there's some way to just tell the compiler "Mirror and associated types are unavailable, propagate that unavailability to everything that uses them in this module, but let us pretend to implement the stuff" so we can avoid sticking an #if on every single bit of code that deals with reflection.

[compnerd]

I'm kinda on the fence about this change. Conceptually, I think that the change is good, but practically, I think that I agree with @yln. I think that adding an extension to String and a few other core types might be nice. An example would be:

extension String {
  public init<T: Error>(reflecting object: T) {
    self = "\(object)"
  }
}

You already change a few places the case where you reflect error into the error's description. This would keep the standard library similar and reduce some of the sprinkled changes.

[kubamracek]

Could I redirect the conversation to #33617 where I'm trying to separate land the first half of this change? This PR is just a follow up to actually turn the flag off for stdlib_minimal.

[kubamracek]

@swift-ci please test

[kubamracek]

preset=stdlib_S_standalone_minimal_macho_x86_64,build,test
@swift-ci please test with toolchain and preset

[benrimmington]

[SR-15661] Tests with "// REQUIRES: reflection" are unsupported