Fix crash when creating predicate with generic root type (#1483)

Author: jmschonfeld

Sources/FoundationEssentials/Predicate/Archiving/PredicateCodableConfiguration.swift

@@ -310,7 +310,7 @@ extension PredicateCodableConfiguration {
             guard root == rootReflectionType.partial, let constructed = constructor(rootReflectionType.genericArguments) else {
                 return nil
             }
-            constructed._validateForPredicateUsage(restrictArguments: false)
+            constructed._validateForPredicateUsage()
             return constructed
         }
     }

Sources/FoundationEssentials/Predicate/KeyPath+Inspection.swift

@@ -50,7 +50,7 @@ extension UInt32 {
 extension AnyKeyPath {
     private static var WORD_SIZE: Int { MemoryLayout<Int>.size }
 
-    func _validateForPredicateUsage(restrictArguments: Bool = true) {
+    func _validateForPredicateUsage() {
         var ptr = unsafeBitCast(self, to: UnsafeRawPointer.self)
         ptr = ptr.advanced(by: Self.WORD_SIZE * 3) // skip isa, type metadata, and KVC string pointers
         let header = ptr.load(as: UInt32.self)
@@ -72,9 +72,7 @@ extension AnyKeyPath {
                 componentWords += 1
             }
             if firstComponentHeader._keyPathComponentHeader_computedHasArguments {
-                if restrictArguments {
-                    fatalError("Predicate does not support keypaths with arguments")
-                }
+                // TODO: Ensure KeyPath only contains generic arguments and not subscript arguments (https://github.com/swiftlang/swift-foundation/issues/1482)
                 let capturesSize = ptr.advanced(by: Self.WORD_SIZE * componentWords).load(as: UInt.self)
                 componentWords += 2 + (Int(capturesSize) / Self.WORD_SIZE)
             }

Tests/FoundationEssentialsTests/PredicateTests.swift

@@ -39,6 +39,22 @@ struct PredicateTestObject2 {
     var a: Bool
 }
 
+
+fileprivate protocol PredicateProducer {
+    var prop: Int { get }
+    func getPredicate() -> Predicate<Self>
+}
+
+fileprivate struct PredicateProducerConformer : PredicateProducer {
+    let prop = 2
+}
+
+extension PredicateProducer {
+    func getPredicate() -> Predicate<Self> {
+        #Predicate { $0.prop == 2 }
+    }
+}
+
 @Suite("Predicate")
 private struct PredicateTests {
     typealias Object = PredicateTestObject
@@ -318,6 +334,12 @@ private struct PredicateTests {
         _ = #Predicate<Foo> { $0.id == 2 }
     }
 
+    @Test func genericKeyPaths() {
+        let obj = PredicateProducerConformer()
+        // Ensure forming a predicate to a generic type does not cause crashes when validating keypaths
+        _ = obj.getPredicate()
+    }
+    
 #if FOUNDATION_EXIT_TESTS
     @Test func unsupportedKeyPaths() async {
         struct Sample {
@@ -370,12 +392,15 @@ private struct PredicateTests {
         }
 
         // subscripts with arguments
+        // This keypath is currently allow but should be considered invalid (https://github.com/swiftlang/swift-foundation/issues/1482)
+        #if false
         await #expect(processExitsWith: .failure) {
             _ = PredicateExpressions.KeyPath(
                 root: PredicateExpressions.Variable(),
                 keyPath: \Sample.[0]
             )
         }
+        #endif
 
         // Optional chaining
         await #expect(processExitsWith: .failure) {