C++ interop crash adding Strings of > 15 bytes to Swift Array.

[efroemling]

Description
When creating a Swift Array of Strings from C++ code (as described in the guide), adding strings with a size greater than 15 bytes causes a crash.

Steps to reproduce
The following steps reproduce the crash for me using XCode 15.0.1 (15A507) on an M1 Max MBP running Sonoma 14.1:

• Create a new ‘Command Line Tool’ project named “TestCommand”.
• Create a new C++ file named ‘test’ (with header). Click ‘Create Bridging Header’ when it asks.
• In TestCommand-Bridging-Header.h, add:

  #include "test.hpp"

• In test.hpp, add:

  void doTest();

• In test.cpp, add:

  #include <TestCommand-Swift.h>
  
  void doTest() {
    // Pass an array back to our Swift code to print.
    auto array = swift::Array<swift::String>::init();
    array.append("foo");
    TestCommand::printStrings(array);
  }

• In main.swift, add:

  // Expose a print call for C++ to use.
  public func printStrings(_ strings: [String]) {
    for s in strings {
      print("GOT STRING", s)
    }
    print("DONE PRINTING.")
  }
  
  // Call our c++ code.
  doTest()

• Under build settings for the TestCommand target, set C++ and Objective-C Interoperability to “C++/Objective C++”
• You should now be able to build and run the project, which should give the following output:

  Hello, World!
  GOT STRING foo
  DONE PRINTING.
  Program ended with exit code: 0
  

• Now, to trigger the crash, simply change the "foo" in test.cpp to "123456789ABCDEFG" and run again. You should see the following output followed by an EXC_BAD_ACCESS crash at the end of the doTest function.

  Hello, World!
  GOT STRING ����������������
  DONE PRINTING.
  <crashes here in swift::Array<swift::String>::~Array()>
  

As per the discussion of this crash on the swift forums, it appears that the threshold for causing a crash is strings > 15 characters which corresponds to String's inline storage size.

Environment

• Swift compiler version info: swift-driver version: 1.87.1 Apple Swift version 5.9 (swiftlang-5.9.0.128.108 clang-1500.0.40.1)

• Xcode version info: Xcode 15.0.1 Build version 15A507

• Deployment target: macOS Sonoma 14.1 (23B73)

[hyp]

Problem with @owned parameter convention here.

[hyp]

I have a fix on hand, just testing it.