Allow Comparable: ~Copyable (#85747)

Builds on #85746 which covers Equatable

stdlib/public/core/Comparable.swift

@@ -135,7 +135,7 @@
 ///   (`FloatingPoint.nan`) compares as neither less than, greater than, nor
 ///   equal to any normal floating-point value. Exceptional values need not
 ///   take part in the strict total order.
-public protocol Comparable: Equatable {
+public protocol Comparable: Equatable, ~Copyable {
   /// Returns a Boolean value indicating whether the value of the first
   /// argument is less than that of the second argument.
   ///
@@ -146,7 +146,7 @@ public protocol Comparable: Equatable {
   /// - Parameters:
   ///   - lhs: A value to compare.
   ///   - rhs: Another value to compare.
-  static func < (lhs: Self, rhs: Self) -> Bool
+  static func < (lhs: borrowing Self, rhs: borrowing Self) -> Bool
 
   /// Returns a Boolean value indicating whether the value of the first
   /// argument is less than or equal to that of the second argument.
@@ -154,7 +154,7 @@ public protocol Comparable: Equatable {
   /// - Parameters:
   ///   - lhs: A value to compare.
   ///   - rhs: Another value to compare.
-  static func <= (lhs: Self, rhs: Self) -> Bool
+  static func <= (lhs: borrowing Self, rhs: borrowing Self) -> Bool
 
   /// Returns a Boolean value indicating whether the value of the first
   /// argument is greater than or equal to that of the second argument.
@@ -162,7 +162,7 @@ public protocol Comparable: Equatable {
   /// - Parameters:
   ///   - lhs: A value to compare.
   ///   - rhs: Another value to compare.
-  static func >= (lhs: Self, rhs: Self) -> Bool
+  static func >= (lhs: borrowing Self, rhs: borrowing Self) -> Bool
 
   /// Returns a Boolean value indicating whether the value of the first
   /// argument is greater than that of the second argument.
@@ -170,10 +170,10 @@ public protocol Comparable: Equatable {
   /// - Parameters:
   ///   - lhs: A value to compare.
   ///   - rhs: Another value to compare.
-  static func > (lhs: Self, rhs: Self) -> Bool
+  static func > (lhs: borrowing Self, rhs: borrowing Self) -> Bool
 }
 
-extension Comparable {
+extension Comparable where Self: ~Copyable {
   /// Returns a Boolean value indicating whether the value of the first argument
   /// is greater than that of the second argument.
   ///
@@ -184,7 +184,8 @@ extension Comparable {
   ///   - lhs: A value to compare.
   ///   - rhs: Another value to compare.
   @inlinable
-  public static func > (lhs: Self, rhs: Self) -> Bool {
+  @_preInverseGenerics
+  public static func > (lhs: borrowing Self, rhs: borrowing Self) -> Bool {
     return rhs < lhs
   }
 
@@ -198,7 +199,8 @@ extension Comparable {
   ///   - lhs: A value to compare.
   ///   - rhs: Another value to compare.
   @inlinable
-  public static func <= (lhs: Self, rhs: Self) -> Bool {
+  @_preInverseGenerics
+  public static func <= (lhs: borrowing Self, rhs: borrowing Self) -> Bool {
     return !(rhs < lhs)
   }
 
@@ -214,7 +216,8 @@ extension Comparable {
   /// - Returns: `true` if `lhs` is greater than or equal to `rhs`; otherwise,
   ///   `false`.
   @inlinable
-  public static func >= (lhs: Self, rhs: Self) -> Bool {
+  @_preInverseGenerics
+  public static func >= (lhs: borrowing Self, rhs: borrowing Self) -> Bool {
     return !(lhs < rhs)
   }
 }

test/Constraints/diagnostics.swift

@@ -1472,14 +1472,12 @@ func testUnwrapFixIts(x: Int?) throws {
   // expected-note@-2 {{force-unwrap using '!' to abort execution if the optional value contains 'nil'}} {{11-11=!}}
   foo(y: x ?? 0) 
 
-  let _ = x < 2 // expected-error {{value of optional type 'Int?' must be unwrapped to a value of type 'Int'}}
-  // expected-note@-1 {{coalesce using '??' to provide a default when the optional value contains 'nil'}} {{12-12= ?? <#default value#>}}
-  // expected-note@-2 {{force-unwrap using '!' to abort execution if the optional value contains 'nil'}} {{12-12=!}}
+  let _ = x < 2 // expected-error {{binary operator '<' cannot be applied to operands of type 'Int?' and 'Int'}}
+  // expected-note@-1 {{overloads for '<' exist with these partially matching parameter lists: (Int, Int)}}
   let _ = x ?? 0 < 2
 
-  let _ = 2 < x // expected-error {{value of optional type 'Int?' must be unwrapped to a value of type 'Int'}}
-  // expected-note@-1 {{coalesce using '??' to provide a default when the optional value contains 'nil'}} {{16-16= ?? <#default value#>}}
-  // expected-note@-2 {{force-unwrap using '!' to abort execution if the optional value contains 'nil'}} {{16-16=!}}
+  let _ = 2 < x // expected-error {{binary operator '<' cannot be applied to operands of type 'Int' and 'Int?'}}
+  // expected-note@-1 {{overloads for '<' exist with these partially matching parameter lists: (Int, Int)}}
   let _ = 2 < x ?? 0
 
   let _: Int = (.optionalIntMember) // expected-error {{value of optional type 'Int?' must be unwrapped to a value of type 'Int'}}
@@ -1497,9 +1495,8 @@ func testUnwrapFixIts(x: Int?) throws {
   // expected-note@-2 {{force-unwrap using '!' to abort execution if the optional value contains 'nil'}} {{36-36=!}}
   let _ = try (.optionalThrowsMember ?? 0) + 1
 
-  let _ = .optionalIntMember?.bitWidth > 0 // expected-error {{value of optional type 'Int?' must be unwrapped to a value of type 'Int'}}
-  // expected-note@-1 {{coalesce using '??' to provide a default when the optional value contains 'nil'}} {{39-39= ?? <#default value#>}}
-  // expected-note@-2 {{force-unwrap using '!' to abort execution if the optional value contains 'nil'}} {{11-11=(}} {{39-39=)!}}
+  let _ = .optionalIntMember?.bitWidth > 0 // expected-error {{binary operator '>' cannot be applied to operands of type 'Int?' and 'Int'}}
+  // expected-note@-1 {{overloads for '>' exist with these partially matching parameter lists: (Int, Int)}}
   let _ = (.optionalIntMember?.bitWidth)! > 0
   let _ = .optionalIntMember?.bitWidth ?? 0 > 0
 

test/SILOptimizer/mandatory_performance_optimizations.sil

@@ -84,7 +84,7 @@ bb0:
 sil [no_allocation] [ossa] @deserialize_and_inline_after_devirtualize : $@convention(thin) (@in Int) -> () {
 bb0(%0 : $*Int):
   %1 = metatype $@thick Int.Type
-  %2 = witness_method $Int, #Comparable."<" : <Self where Self : Comparable> (Self.Type) -> (Self, Self) -> Bool : $@convention(witness_method: Comparable) <τ_0_0 where τ_0_0 : Comparable> (@in_guaranteed τ_0_0, @in_guaranteed τ_0_0, @thick τ_0_0.Type) -> Bool
+  %2 = witness_method $Int, #Comparable."<" : <Self where Self : Comparable, Self : ~Copyable> (Self.Type) -> (borrowing Self, borrowing Self) -> Bool : $@convention(witness_method: Comparable) <τ_0_0 where τ_0_0 : Comparable> (@in_guaranteed τ_0_0, @in_guaranteed τ_0_0, @thick τ_0_0.Type) -> Bool
   %3 = apply %2<Int>(%0, %0, %1) : $@convention(witness_method: Comparable) <τ_0_0 where τ_0_0 : Comparable> (@in_guaranteed τ_0_0, @in_guaranteed τ_0_0, @thick τ_0_0.Type) -> Bool
   %4 = tuple()
   return %4 : $()
@@ -124,7 +124,7 @@ bb0(%0 : $*Int, %1 : $*Int, %2 : $@thick Int.Type):
 
 sil_witness_table public_external [serialized] Int: Comparable module Swift {
   base_protocol Equatable: Int: Equatable module Swift
-  method #Comparable."<": <Self where Self : Comparable> (Self.Type) -> (Self, Self) -> Bool : @$sSiSLsSL1loiySbx_xtFZTW
+  method #Comparable."<": <Self where Self : Comparable, Self : ~Copyable> (Self.Type) -> (borrowing Self, borrowing Self) -> Bool : @$sSiSLsSL1loiySbx_xtFZTW
 }
 
 sil [ossa] @get_int_value : $@convention(thin) () -> Int32 {

test/api-digester/Outputs/stability-stdlib-source-base.swift.expected

@@ -71,7 +71,6 @@ Protocol CodingKey has added inherited protocol Copyable
 Protocol CodingKey has added inherited protocol Escapable
 Protocol Collection has added inherited protocol Copyable
 Protocol Collection has added inherited protocol Escapable
-Protocol Comparable has added inherited protocol Copyable
 Protocol Comparable has added inherited protocol Escapable
 Protocol CustomDebugStringConvertible has added inherited protocol Copyable
 Protocol CustomDebugStringConvertible has added inherited protocol Escapable
@@ -387,3 +386,18 @@ Func Equatable.==(_:_:) has generic signature change from <Self where Self : Swi
 Func Equatable.==(_:_:) has parameter 0 changing from Default to Shared
 Func Equatable.==(_:_:) has parameter 1 changing from Default to Shared
 
+// Comparable: ~Copyable
+Protocol Comparable has generic signature change from <Self : Swift.Equatable> to <Self : Swift.Equatable, Self : ~Copyable>
+Func Comparable.<(_:_:) has generic signature change from <Self where Self : Swift.Comparable> to <Self where Self : Swift.Comparable, Self : ~Copyable>
+Func Comparable.<(_:_:) has parameter 0 changing from Default to Shared
+Func Comparable.<(_:_:) has parameter 1 changing from Default to Shared
+Func Comparable.<=(_:_:) has generic signature change from <Self where Self : Swift.Comparable> to <Self where Self : Swift.Comparable, Self : ~Copyable>
+Func Comparable.<=(_:_:) has parameter 0 changing from Default to Shared
+Func Comparable.<=(_:_:) has parameter 1 changing from Default to Shared
+Func Comparable.>(_:_:) has generic signature change from <Self where Self : Swift.Comparable> to <Self where Self : Swift.Comparable, Self : ~Copyable>
+Func Comparable.>(_:_:) has parameter 0 changing from Default to Shared
+Func Comparable.>(_:_:) has parameter 1 changing from Default to Shared
+Func Comparable.>=(_:_:) has generic signature change from <Self where Self : Swift.Comparable> to <Self where Self : Swift.Comparable, Self : ~Copyable>
+Func Comparable.>=(_:_:) has parameter 0 changing from Default to Shared
+Func Comparable.>=(_:_:) has parameter 1 changing from Default to Shared
+

test/api-digester/stability-stdlib-abi-without-asserts.test

@@ -189,7 +189,6 @@ Protocol CodingKey has added inherited protocol Copyable
 Protocol CodingKey has added inherited protocol Escapable
 Protocol Collection has added inherited protocol Copyable
 Protocol Collection has added inherited protocol Escapable
-Protocol Comparable has added inherited protocol Copyable
 Protocol Comparable has added inherited protocol Escapable
 Protocol CustomDebugStringConvertible has added inherited protocol Copyable
 Protocol CustomDebugStringConvertible has added inherited protocol Escapable
@@ -892,4 +891,26 @@ Func Equatable.==(_:_:) has generic signature change from <Self where Self : Swi
 Func Equatable.==(_:_:) has parameter 0 changing from Default to Shared
 Func Equatable.==(_:_:) has parameter 1 changing from Default to Shared
 
+// Comparable: ~Copyable
+Protocol Comparable has generic signature change from <Self : Swift.Equatable> to <Self : Swift.Equatable, Self : ~Copyable>
+Func Comparable.<(_:_:) has generic signature change from <Self where Self : Swift.Comparable> to <Self where Self : Swift.Comparable, Self : ~Copyable>
+Func Comparable.<(_:_:) has parameter 0 changing from Default to Shared
+Func Comparable.<(_:_:) has parameter 1 changing from Default to Shared
+Func Comparable.<=(_:_:) has generic signature change from <Self where Self : Swift.Comparable> to <Self where Self : Swift.Comparable, Self : ~Copyable>
+Func Comparable.<=(_:_:) has mangled name changing from 'static (extension in Swift):Swift.Comparable.<= infix(A, A) -> Swift.Bool' to 'static (extension in Swift):Swift.Comparable< where A: ~Swift.Copyable>.<= infix(A, A) -> Swift.Bool'
+Func Comparable.<=(_:_:) has parameter 0 changing from Default to Shared
+Func Comparable.<=(_:_:) has parameter 1 changing from Default to Shared
+Func Comparable.<=(_:_:) is now with @_preInverseGenerics
+Func Comparable.>(_:_:) has generic signature change from <Self where Self : Swift.Comparable> to <Self where Self : Swift.Comparable, Self : ~Copyable>
+Func Comparable.>(_:_:) has mangled name changing from 'static (extension in Swift):Swift.Comparable.> infix(A, A) -> Swift.Bool' to 'static (extension in Swift):Swift.Comparable< where A: ~Swift.Copyable>.> infix(A, A) -> Swift.Bool'
+Func Comparable.>(_:_:) has parameter 0 changing from Default to Shared
+Func Comparable.>(_:_:) has parameter 1 changing from Default to Shared
+Func Comparable.>(_:_:) is now with @_preInverseGenerics
+Func Comparable.>=(_:_:) has generic signature change from <Self where Self : Swift.Comparable> to <Self where Self : Swift.Comparable, Self : ~Copyable>
+Func Comparable.>=(_:_:) has mangled name changing from 'static (extension in Swift):Swift.Comparable.>= infix(A, A) -> Swift.Bool' to 'static (extension in Swift):Swift.Comparable< where A: ~Swift.Copyable>.>= infix(A, A) -> Swift.Bool'
+Func Comparable.>=(_:_:) has parameter 0 changing from Default to Shared
+Func Comparable.>=(_:_:) has parameter 1 changing from Default to Shared
+Func Comparable.>=(_:_:) is now with @_preInverseGenerics
+
+
 // *** DO NOT DISABLE OR XFAIL THIS TEST. *** (See comment above.)

test/stdlib/NoncopyableComparable.swift

@@ -0,0 +1,85 @@
+//===--- NoncopyableComparable.swift - tests for Comparable: ~Copyable -------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 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
+// REQUIRES: executable_test
+
+import StdlibUnittest
+
+let NoncopyableComparableTests = TestSuite("NoncopyableComparable")
+
+struct Noncopyable<Wrapped: ~Copyable>: ~Copyable {
+  var wrapped: Wrapped
+}
+
+extension Noncopyable: Equatable where Wrapped: Equatable & ~Copyable { }
+
+extension Noncopyable: Comparable where Wrapped: Comparable & ~Copyable {
+  static func < (lhs: borrowing Self, rhs: borrowing Self) -> Bool { lhs.wrapped < rhs.wrapped }
+}
+
+extension Comparable where Self: ~Copyable {
+  func isLessThan(_ other: borrowing Self) -> Bool {
+    self < other
+  }
+}
+
+func isLessOrEqual<T: Comparable & ~Copyable>(_ lhs: borrowing T, _ rhs: borrowing T) -> Bool {
+  lhs <= rhs
+}
+
+@available(SwiftStdlib 6.2, *)
+extension InlineArray where Element: Comparable & ~Copyable {
+    func minIndex() -> Int? {
+        indices.min { self[$0] < self[$1] }
+    }
+	
+	func inReverseOrder() -> Bool {
+		for i in indices.dropFirst() {
+			if self[i] > self[i-1] { return false }
+		}
+		return true
+	}
+}
+
+NoncopyableComparableTests.test("comparing noncopyables") {
+  let a = Noncopyable(wrapped: 0)
+  let b = Noncopyable(wrapped: 1)
+  let c = Noncopyable(wrapped: 2)
+  
+  expectTrue(a < b)
+  expectTrue(c > a)
+  expectFalse(a < a)
+  expectFalse(a > c)
+  expectFalse(c <= a)
+  expectTrue(a <= a)
+  expectTrue(a < b && b < c)
+
+  expectTrue(a.isLessThan(b))
+  expectTrue(isLessOrEqual(a,b))
+  expectFalse(b.isLessThan(a))
+
+  let nc2 = Noncopyable(wrapped: Noncopyable(wrapped: "1"))
+  expectFalse(nc2 < nc2)
+  expectFalse(nc2 > nc2)
+  expectTrue(nc2 >= nc2)
+  expectTrue(nc2 < .init(wrapped: .init(wrapped: "2")))
+
+  guard #available(SwiftStdlib 6.2, *) else { return }
+
+  var array: [3 of Noncopyable] = [c,b,a]
+  expectTrue(array.minIndex() == 2)
+  expectTrue(array.inReverseOrder())
+  array.swapAt(1, 2)
+  expectFalse(array.inReverseOrder())
+ }
+
+runAllTests()

test/stdlib/StringDiagnostics.swift

@@ -34,14 +34,18 @@ func testAmbiguousStringComparisons(s: String) {
   let nsString = s as NSString
   let a1 = s as NSString == nsString
   let a2 = s as NSString != nsString
-  let a3 = s < nsString // expected-error{{'NSString' is not implicitly convertible to 'String'; did you mean to use 'as' to explicitly convert?}} {{24-24= as String}}
+  let a3 = s < nsString 
+  // expected-error@-1{{binary operator '<' cannot be applied to operands of type 'String' and 'NSString'}}
+  // expected-note@-2{{overloads for '<' exist with these partially matching parameter lists: (String, String)}}
   let a4 = s <= nsString // expected-error{{'NSString' is not implicitly convertible to 'String'; did you mean to use 'as' to explicitly convert?}} {{25-25= as String}}
   let a5 = s >= nsString // expected-error{{'NSString' is not implicitly convertible to 'String'; did you mean to use 'as' to explicitly convert?}} {{25-25= as String}}
   let a6 = s > nsString // expected-error{{'NSString' is not implicitly convertible to 'String'; did you mean to use 'as' to explicitly convert?}} {{24-24= as String}}
   // now the other way
   let a7 = nsString == s as NSString
   let a8 = nsString != s as NSString
-  let a9 = nsString < s // expected-error{{'NSString' is not implicitly convertible to 'String'; did you mean to use 'as' to explicitly convert?}} {{20-20= as String}}
+  let a9 = nsString < s 
+  // expected-error@-1{{binary operator '<' cannot be applied to operands of type 'NSString' and 'String'}}
+  // expected-note@-2{{overloads for '<' exist with these partially matching parameter lists: (String, String)}}
   let a10 = nsString <= s // expected-error{{'NSString' is not implicitly convertible to 'String'; did you mean to use 'as' to explicitly convert?}} {{21-21= as String}}
   let a11 = nsString >= s // expected-error{{'NSString' is not implicitly convertible to 'String'; did you mean to use 'as' to explicitly convert?}} {{21-21= as String}}
   let a12 = nsString > s // expected-error{{'NSString' is not implicitly convertible to 'String'; did you mean to use 'as' to explicitly convert?}} {{21-21= as String}}