[StdLib][RFC][DNM] Add isIdentical Methods for Quick Comparisons to Dictionary and Set

benchmark/CMakeLists.txt

@@ -80,6 +80,7 @@ set(SWIFT_BENCH_MODULES
     single-source/DictionaryCompactMapValues
     single-source/DictionaryCopy
     single-source/DictionaryGroup
+    single-source/DictionaryIdentical
     single-source/DictionaryKeysContains
     single-source/DictionaryLiteralTest
     single-source/DictionaryOfAnyHashableStrings
@@ -173,6 +174,7 @@ set(SWIFT_BENCH_MODULES
     # Disabled while layout prespecializations are experimental
     #single-source/SimpleArraySpecialization
     single-source/SequenceAlgos
+    single-source/SetIdentical
     single-source/SetTests
     single-source/SevenBoom
     single-source/Sim2DArray

benchmark/single-source/DictionaryIdentical.swift

@@ -0,0 +1,46 @@
+//===--- DictionaryIdentical.swift ----------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import TestsUtils
+
+public let benchmarks = [
+  BenchmarkInfo(name: "DictionaryEqualUnique", runFunction: run_DictionaryEqualUnique, tags: [.validation, .api, .Dictionary]),
+  BenchmarkInfo(name: "DictionaryEqualShared", runFunction: run_DictionaryEqualShared, tags: [.validation, .api, .Dictionary]),
+  BenchmarkInfo(name: "DictionaryIdentical", runFunction: run_DictionaryIdentical, tags: [.validation, .api, .Dictionary]),
+]
+
+@inline(never)
+public func run_DictionaryEqualUnique(_ n: Int) {
+  let d1 = Dictionary(uniqueKeysWithValues: zip(1...n, 1...n))
+  let d2 = Dictionary(uniqueKeysWithValues: zip(1...n, 1...n))
+  for _ in 0 ..< 100_000 {
+    check(d1 == d2)
+  }
+}
+
+@inline(never)
+public func run_DictionaryEqualShared(_ n: Int) {
+  let d1 = Dictionary(uniqueKeysWithValues: zip(1...n, 1...n))
+  let d2 = d1
+  for _ in 0 ..< 100_000 {
+    check(d1 == d2)
+  }
+}
+
+@inline(never)
+public func run_DictionaryIdentical(_ n: Int) {
+  let d1 = Dictionary(uniqueKeysWithValues: zip(1...n, 1...n))
+  let d2 = d1
+  for _ in 0 ..< 100_000 {
+    check(d1.isIdentical(to: d2))
+  }
+}

benchmark/single-source/SetIdentical.swift

@@ -0,0 +1,46 @@
+//===--- SetIdentical.swift -----------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import TestsUtils
+
+public let benchmarks = [
+  BenchmarkInfo(name: "SetEqualUnique", runFunction: run_SetEqualUnique, tags: [.validation, .api, .Set]),
+  BenchmarkInfo(name: "SetEqualShared", runFunction: run_SetEqualShared, tags: [.validation, .api, .Set]),
+  BenchmarkInfo(name: "SetIdentical", runFunction: run_SetIdentical, tags: [.validation, .api, .Set]),
+]
+
+@inline(never)
+public func run_SetEqualUnique(_ n: Int) {
+  let s1 = Set(1...n)
+  let s2 = Set(1...n)
+  for _ in 0 ..< 100_000 {
+    check(s1 == s2)
+  }
+}
+
+@inline(never)
+public func run_SetEqualShared(_ n: Int) {
+  let s1 = Set(1...n)
+  let s2 = s1
+  for _ in 0 ..< 100_000 {
+    check(s1 == s2)
+  }
+}
+
+@inline(never)
+public func run_SetIdentical(_ n: Int) {
+  let s1 = Set(1...n)
+  let s2 = s1
+  for _ in 0 ..< 100_000 {
+    check(s1.isIdentical(to: s2))
+  }
+}

benchmark/utils/main.swift

@@ -75,6 +75,7 @@ import DictionaryBridgeToObjC
 import DictionaryCompactMapValues
 import DictionaryCopy
 import DictionaryGroup
+import DictionaryIdentical
 import DictionaryKeysContains
 import DictionaryLiteralTest
 import DictionaryOfAnyHashableStrings
@@ -177,6 +178,7 @@ import RomanNumbers
 import SIMDRandomMask
 import SIMDReduceInteger
 import SequenceAlgos
+import SetIdentical
 import SetTests
 import SevenBoom
 import Sim2DArray
@@ -276,6 +278,7 @@ register(DictionaryBridgeToObjC.benchmarks)
 register(DictionaryCompactMapValues.benchmarks)
 register(DictionaryCopy.benchmarks)
 register(DictionaryGroup.benchmarks)
+register(DictionaryIdentical.benchmarks)
 register(DictionaryKeysContains.benchmarks)
 register(DictionaryLiteralTest.benchmarks)
 register(DictionaryOfAnyHashableStrings.benchmarks)
@@ -379,6 +382,7 @@ register(RomanNumbers.benchmarks)
 register(SIMDRandomMask.benchmarks)
 register(SIMDReduceInteger.benchmarks)
 register(SequenceAlgos.benchmarks)
+register(SetIdentical.benchmarks)
 register(SetTests.benchmarks)
 register(SevenBoom.benchmarks)
 register(Sim2DArray.benchmarks)

stdlib/public/core/Dictionary.swift

@@ -2154,3 +2154,43 @@ extension Dictionary.Index: @unchecked Sendable
   where Key: Sendable, Value: Sendable {}
 extension Dictionary.Iterator: @unchecked Sendable
   where Key: Sendable, Value: Sendable {}
+
+extension Dictionary {
+  /// Returns a boolean value indicating whether this dictionary is identical to
+  /// `other`.
+  ///
+  /// Two dictionary values are identical if there is no way to distinguish
+  /// between them.
+  ///
+  /// Comparing dictionaries this way includes comparing (normally) hidden
+  /// implementation details such as the memory location of any underlying
+  /// dictionary storage object. Therefore, identical dictionaries are
+  /// guaranteed to compare equal with `==`, but not all equal dictionaries are
+  /// considered identical.
+  ///
+  /// - Performance: O(1)
+  @_alwaysEmitIntoClient
+  public func isIdentical(to other: Self) -> Bool {
+#if _runtime(_ObjC)
+    if
+      self._variant.isNative,
+      other._variant.isNative,
+      unsafe (self._variant.asNative._storage === other._variant.asNative._storage)
+    {
+      return true
+    }
+    if
+      !self._variant.isNative,
+      !other._variant.isNative,
+      self._variant.asCocoa.object === other._variant.asCocoa.object
+    {
+      return true
+    }
+#else
+    if unsafe (self._variant.asNative._storage === other._variant.asNative._storage) {
+      return true
+    }
+#endif
+    return false
+  }
+}

stdlib/public/core/Set.swift

@@ -1658,3 +1658,42 @@ extension Set.Index: @unchecked Sendable
   where Element: Sendable { }
 extension Set.Iterator: @unchecked Sendable
   where Element: Sendable { }
+
+extension Set {
+  /// Returns a boolean value indicating whether this set is identical to
+  /// `other`.
+  ///
+  /// Two set values are identical if there is no way to distinguish between
+  /// them.
+  ///
+  /// Comparing sets this way includes comparing (normally) hidden
+  /// implementation details such as the memory location of any underlying set
+  /// storage object. Therefore, identical sets are guaranteed to compare equal
+  /// with `==`, but not all equal sets are considered identical.
+  ///
+  /// - Performance: O(1)
+  @_alwaysEmitIntoClient
+  public func isIdentical(to other: Self) -> Bool {
+#if _runtime(_ObjC)
+    if
+      self._variant.isNative,
+      other._variant.isNative,
+      unsafe (self._variant.asNative._storage === other._variant.asNative._storage)
+    {
+      return true
+    }
+    if
+      !self._variant.isNative,
+      !other._variant.isNative,
+      self._variant.asCocoa.object === other._variant.asCocoa.object
+    {
+      return true
+    }
+#else
+    if unsafe (self._variant.asNative._storage === other._variant.asNative._storage) {
+      return true
+    }
+#endif
+    return false
+  }
+}

test/stdlib/DictionaryTests.swift

@@ -0,0 +1,43 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// RUN: %target-run-simple-swift(-parse-as-library)
+// REQUIRES: executable_test
+// END.
+//
+//===----------------------------------------------------------------------===//
+
+import StdlibUnittest
+
+@main
+enum DictionaryTests {
+  static func main() {
+    let testSuite = TestSuite("DictionaryTests")
+    testSuite.test("Identical", testIdentical)
+    runAllTests()
+  }
+
+  static func testIdentical() {
+    let d1: Dictionary = ["a": 1, "b": 2, "c": 3]
+    expectTrue(d1.isIdentical(to: d1))
+
+    let d2: Dictionary = d1
+    expectTrue(d1.isIdentical(to: d2))
+
+    var d3: Dictionary = d2
+    d3.reserveCapacity(0)
+    expectFalse(d1.isIdentical(to: d3))
+
+    let d4: Dictionary = ["a": 1, "b": 2, "c": 3]
+    expectFalse(d1.isIdentical(to: d4))
+  }
+}

test/stdlib/SetTests.swift

@@ -0,0 +1,43 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// RUN: %target-run-simple-swift(-parse-as-library)
+// REQUIRES: executable_test
+// END.
+//
+//===----------------------------------------------------------------------===//
+
+import StdlibUnittest
+
+@main
+enum SetTests {
+  static func main() {
+    let testSuite = TestSuite("SetTests")
+    testSuite.test("Identical", testIdentical)
+    runAllTests()
+  }
+
+  static func testIdentical() {
+    let s1: Set = [0, 1, 2, 3]
+    expectTrue(s1.isIdentical(to: s1))
+
+    let s2: Set = s1
+    expectTrue(s1.isIdentical(to: s2))
+
+    var s3: Set = s2
+    s3.reserveCapacity(0)
+    expectFalse(s1.isIdentical(to: s3))
+
+    let s4: Set = [0, 1, 2, 3]
+    expectFalse(s1.isIdentical(to: s4))
+  }
+}