Remove generalization of the result for Sequence.reduce

Author: Azoy

stdlib/public/core/SequenceAlgorithms.swift

@@ -665,9 +665,9 @@ extension Sequence {
   ///
   /// - Complexity: O(*n*), where *n* is the length of the sequence.
   @_alwaysEmitIntoClient
-  public func reduce<Result: ~Copyable, E: Error>(
-    _ initialResult: consuming Result,
-    _ nextPartialResult: (borrowing Result, Element) throws(E) -> Result
+  public func reduce<Result, E: Error>(
+    _ initialResult: Result,
+    _ nextPartialResult: (Result, Element) throws(E) -> Result
   ) throws(E) -> Result {
     var accumulator = initialResult
     for element in self {
@@ -721,8 +721,8 @@ extension Sequence {
   ///
   /// - Complexity: O(*n*), where *n* is the length of the sequence.
   @_alwaysEmitIntoClient
-  public func reduce<Result: ~Copyable, E: Error>(
-    into initialResult: consuming Result,
+  public func reduce<Result, E: Error>(
+    into initialResult: __owned Result,
     _ updateAccumulatingResult: (inout Result, Element) throws(E) -> ()
   ) throws(E) -> Result {
     var accumulator = initialResult

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

@@ -393,11 +393,10 @@ Func Sequence.forEach(_:) has generic signature change from <Self where Self : S
 Func Sequence.forEach(_:) is now without @rethrows
 
 // Adoption of typed throws for Sequence.reduce(_:_:)
-Func Sequence.reduce(_:_:) has generic signature change from <Self, Result where Self : Swift.Sequence> to <Self, Result, E where Self : Swift.Sequence, E : Swift.Error, Result : ~Copyable>
-Func Sequence.reduce(_:_:) has parameter 0 changing from Default to Owned
+Func Sequence.reduce(_:_:) has generic signature change from <Self, Result where Self : Swift.Sequence> to <Self, Result, E where Self : Swift.Sequence, E : Swift.Error>
 Func Sequence.reduce(_:_:) is now without @rethrows
 
 // Adoption of typed throws for Sequence.reduce(into:_:)
-Func Sequence.reduce(into:_:) has generic signature change from <Self, Result where Self : Swift.Sequence> to <Self, Result, E where Self : Swift.Sequence, E : Swift.Error, Result : ~Copyable>
+Func Sequence.reduce(into:_:) has generic signature change from <Self, Result where Self : Swift.Sequence> to <Self, Result, E where Self : Swift.Sequence, E : Swift.Error>
 Func Sequence.reduce(into:_:) has parameter 1 type change from (inout Result, Self.Element) throws -> () to (inout Result, Self.Element) throws(E) -> ()
 Func Sequence.reduce(into:_:) is now without @rethrows