Print whether the metadata is a _ContiguousArrayStorage with a class element type

Author: aschwaighofer

tools/swift-inspect/Sources/swift-inspect/Metadata.swift

@@ -35,7 +35,8 @@ extension Allocation {
     let ptr = context.metadataPointer(allocation: allocation_t)
     if ptr != 0 {
       let name = context.name(metadata: ptr) ?? "<unknown>"
-      return .init(ptr: ptr, name: name)
+      let isClass = context.isAContiguousArrayOfClassElementType(metadata: ptr)
+      return .init(ptr: ptr, name: name, isArrayOfClass: isClass)
     } else {
       return nil
     }
@@ -59,6 +60,7 @@ struct Metadata {
   let ptr: swift_reflection_ptr_t
   var allocation: Allocation? = nil
   let name: String
+  let isArrayOfClass: Bool
 
   var offset: Int? { allocation.map { Int(self.ptr - $0.ptr) } }
 }

tools/swift-inspect/Sources/swift-inspect/RemoteMirrorExtensions.swift

@@ -31,6 +31,32 @@ extension SwiftReflectionContextRef {
     return String(cString: cstr)
   }
 
+  func isAContiguousArrayOfClassElementType(metadata: swift_reflection_ptr_t) ->
+  Bool {
+    guard let name = name(metadata: metadata) else { return false }
+    guard name.starts(with: "Swift._ContiguousArrayStorage") else {
+        return false
+    }
+    let tr = swift_reflection_typeRefForMetadata(self, UInt(metadata));
+    guard tr != 0 else {
+        fatalError("swift_reflection_typeRefForMetadata is null")
+        return false
+    }
+    let genericArgCnt = swift_reflection_genericArgumentCountOfTypeRef(tr);
+    guard genericArgCnt == 1 else {
+        fatalError("swift_reflection_genericArgumentCountOfTypeRef is \(genericArgCnt)")
+        return false
+    }
+
+    let argTr = swift_reflection_genericArgumentOfTypeRef(tr, 0)
+    guard argTr != 0 else {
+        fatalError("swift_reflection_genericArgumentOfTypeRef is null")
+        return false
+    }
+    let typeInfo = swift_reflection_infoForTypeRef(self, argTr)
+    return typeInfo.Kind == SWIFT_STRONG_REFERENCE
+  }
+
   func name(proto: swift_reflection_ptr_t) -> String? {
     guard let cstr = swift_reflection_copyDemangledNameForProtocolDescriptor(
       self, proto) else { return nil }

tools/swift-inspect/Sources/swift-inspect/main.swift

@@ -56,7 +56,7 @@ func dumpGenericMetadata(
   let metadatas = allocations.findGenericMetadata(in: context)
   let backtraces = backtraceStyle != nil ? context.allocationBacktraces : [:]
 
-  print("Address","Allocation","Size","Offset","Name", separator: "\t")
+  print("Address","Allocation","Size","Offset","isArrayOfClass", "Name", separator: "\t")
   for metadata in metadatas {
     print("\(hex: metadata.ptr)", terminator: "\t")
 
@@ -66,6 +66,7 @@ func dumpGenericMetadata(
     } else {
       print("???\t???\t???", terminator: "\t")
     }
+    print(metadata.isArrayOfClass, terminator: "\t")
     print(metadata.name)
     if let allocation = metadata.allocation {
       printBacktrace(style: backtraceStyle, for: allocation.ptr, in: backtraces, inspector: inspector)