Fix Xcode 15.3 Release Crash

[stephencelis]

A SIL function we load seems to be unavailable, so let's limit old key path printing to DEBUG builds.

Fixes #107.

[aschwaighofer]

@stephencelis

The use of _silgen_name with a Swift runtime function (or also importing a C header file with runtime functions) is unsupported and strongly discouraged.

swift-custom-dump/Sources/CustomDump/Conformances/KeyPath.swift

Line 699 in 02d0f05

internal func _allocObject(_: UnsafeMutableRawPointer, _: Int, _: Int) -> AnyObject?

Swift compilers starting with Xcode 15.3 allow for the use of the Builtin module. In your case, you can use the Builtin.allocWithTailElems_1 to mimic what the standard library does.

Something like the following should work (I have only tested that this compiles with Xcode 15.3):

diff --git a/Sources/CustomDump/Conformances/KeyPath.swift b/Sources/CustomDump/Conformances/KeyPath.swift
index 24dacbc..380109e 100644
--- a/Sources/CustomDump/Conformances/KeyPath.swift
+++ b/Sources/CustomDump/Conformances/KeyPath.swift
@@ -1,5 +1,9 @@
 import Foundation
 
+#if swift(>=5.10)
+import Builtin
+#endif
+
 extension AnyKeyPath: CustomDumpStringConvertible {
   public var customDumpDescription: String {
     // NB: We gate this to 5.9+ due to this crasher: https://github.com/apple/swift/issues/64865
@@ -721,12 +725,17 @@ extension AnyKeyPath: CustomDumpStringConvertible {
 
       let alignment = metadata.instanceAlignMask | tailAlignMask
 
+    #if swift(>=5.10)
+      let object = Builtin.allocWithTailElems_1(self, (bytes/4)._builtinWordValue,
+                                                Int32.self)
+      let base = UnsafeMutableRawPointer(Builtin.projectTailElems(object,
+                                                                  Int32.self))
+    #else
       let object = _allocObject(
         UnsafeMutableRawPointer(mutating: metadata.pointer),
         size,
         alignment
       )
-
       guard object != nil else {
         fatalError("Allocating \(self) instance failed for keypath reflection")
       }
@@ -736,6 +745,8 @@ extension AnyKeyPath: CustomDumpStringConvertible {
       let base =
         unsafeBitCast(object, to: UnsafeMutableRawPointer.self) + MemoryLayout<Int>.size * 2
 
+    #endif
+
       // The first word is the kvc string pointer. Set it to 0 (nil).
       base.storeBytes(of: 0, as: Int.self)
 

And probably a Package file like (not a swift package configuration expert by any means):

diff --git a/Package@swift-5.10.swift b/Package@swift-5.10.swift
new file mode 100644
index 0000000..73cd1b7
--- /dev/null
+++ b/Package@swift-5.10.swift
+// swift-tools-version:5.10
+
+import PackageDescription
+
+let package = Package(
+  name: "swift-custom-dump",
+  platforms: [
+    .iOS(.v13),
+    .macOS(.v10_15),
+    .tvOS(.v13),
+    .watchOS(.v6),
+  ],
+  products: [
+    .library(
+      name: "CustomDump",
+      targets: ["CustomDump"]
+    )
+  ],
+  dependencies: [
+    .package(url: "https://github.com/pointfreeco/xctest-dynamic-overlay", from: "1.0.0")
+  ],
+  targets: [
+    .target(
+      name: "CustomDump",
+      dependencies: [
+        .product(name: "XCTestDynamicOverlay", package: "xctest-dynamic-overlay")
+      ],
+      swiftSettings: [.enableExperimentalFeature("BuiltinModule")]
+    ),
+    .testTarget(
+      name: "CustomDumpTests",
+      dependencies: [
+        "CustomDump"
+      ],
+      swiftSettings: [.enableExperimentalFeature("BuiltinModule")]
+    ),
+  ]
+)

[stephencelis]

@aschwaighofer Thanks for chiming in! Good to know about that option. I'm not sure swiftSettings can be customized for distributed package releases, though (at the very least we've found that the presence of unsafeFlags can break a versioned release).

Luckily we think we can delete the original code path, since it was mainly there for Swift <5.9, and we don't mind degrading the debug info for earlier versions of Swift.