`rustc --target aarch64-apple-ios --print cfg` shouldn't ICE

[japaric]

$ rustup run stable rustc --target aarch64-apple-ios --print cfg
error: internal compiler error: unexpected panic
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
thread 'rustc' panicked at 'failed to get iphoneos SDK path: No such file or directory (os error 2)', ../src/librustc_back/target/apple_ios_base.rs:59

I should be able to query information about the target even if I don't have the SDK installed.

Meta

$ rustup run stable rustc -V
rustc 1.11.0 (9b21dcd6a 2016-08-15)

I don't know if this has been fixed on nightly because of #36156

cc @alexcrichton

[alexcrichton]

I believe this has essentially always been the case, but I'd love to have a fix! I think the best choice here is to delay the pieces of the iOS target that are fallible until we actually need them, for example at link time.

[TimNN]

I think this is basically a duplicate of #29812.

[japaric]

I think this is basically a duplicate of #29812.

Yup, I'll close this one.