This adds in hooks so that the new hash/isEqual interop
(which bridges Obj-C hash/isEqual: calls to the corresponding
Swift Hashable/Equatable conformances) can be selectively
disabled based on the OS and/or client.
For now, enable the new semantics everywhere except Apple platforms
(which have legacy apps that may be relying on the old semantics).
For Apple platforms, enable the new stricter boxing semantics only
for apps built against the Fall 2023 or later SDK. This
avoids breaking apps that relied on the old behavior and
have not been updated since then.
This replaces a number of `#include`-s like this:
```
#include "../../../stdlib/public/SwiftShims/Visibility.h"
```
with this:
```
#include "swift/shims/Visibility.h"
```
This is needed to allow SwiftCompilerSources to use C++ headers which include SwiftShims headers. Currently trying to do that results in errors:
```
swift/swift/include/swift/Demangling/../../../stdlib/public/SwiftShims/module.modulemap:1:8: error: redefinition of module 'SwiftShims'
module SwiftShims {
^
Builds.noindex/swift/swift/bootstrapping0/lib/swift/shims/module.modulemap:1:8: note: previously defined here
module SwiftShims {
^
```
This happens because the headers in both the source dir and the build dir refer to SwiftShims headers by relative path, and both the source root and the build root contain SwiftShims headers (which are equivalent, but since they are located in different dirs, Clang treats them as different modules).
Swift 5.7 added stronger index validation for `String`, so some illegal cases that previously triggered inconsistently diagnosed out of bounds accesses now result in reliable runtime errors. Similarly, attempts at applying an index originally vended by a UTF-8 string on a UTF-16 string now result in a reliable runtime error.
As is usually the case, new traps to the stdlib exposes code that contains previously undiagnosed / unreliably diagnosed coding issues.
Allow invalid code in binaries built with earlier versions of the stdlib to continue running with the 5.7 library by disabling some of the new traps based on the version of Swift the binary was built with.
In the case of an index encoding mismatch, allow transcoding of string storage regardless of the direction of the mismatch. (Previously we only allowed transcoding a UTF-8 string to UTF-16.)
rdar://93379333
* Refactor Bincompat
Organize everything around internal functions that test for
a particular OS version.
Correctly handle cases where we don't know the version of the app.
Make all bincompat functions consistently return `true` for the
legacy semantics, `false` for new semantics. Consistently name
them all to reflect this.
* Conditionalize the support for SR-14635
SR-14635 pointed out a hole in the updated dynamic casting logic
that allowed certain casts that should have been illegal.
In particular, when casting certain types to Obj-C protocols,
the Swift value gets boxed; we would permit the cast to succeed
whenever the resulting box satisfied the protocol. For example,
this allowed any Swift value to be cast to `NSCopying` regardless of
whether or not it implemented the required `copy(with:)` method.
This was fixed in #37683 to reject such casts but of course some folks were
depending on this behavior to pass Swift data into Obj-C functions.
(The properly supported approach for passing arbitrary Swift data into
Obj-C functions is to cast the Swift value to `AnyObject`.)
This change makes that new behavior conditional. For now,
the legacy semantics are enabled on Apple platforms and the
new semantics are in use everywhere else. This will allow
us to gradually enable enforcement of the new behavior over
time.
* Just skip this test on Apple platforms, since it is inconsistently implemented there (and is therefore not really testable)
