When importing C++ methods, Swift always assumes that methods named `begin()` and `end()` are unsafe, since these methods commonly return iterator types that are inherently unsafe in Swift.
Some additional logic in Sema tries to diagnose usages of `.begin()` and `.end()` from Swift and suggest safe alternatives. That logic had a null pointer dereference bug.
rdar://153814676 / resolves https://github.com/swiftlang/swift/issues/82361
(cherry picked from commit 883ff18adb)
These tests are using FileCheck to check the result of diagnostic
formatting in ways that don't match the new formatter. Force the old
formatter or, where possible, generalize so that they match both
formatters.
