Reimplement Zip to fix reference crash issue

RemainingCombineInterface.swift

@@ -901,52 +901,3 @@ extension Publishers.MergeMany : Equatable where Upstream : Equatable {
     ///   - rhs: Another value to compare.
     public static func == (lhs: Publishers.MergeMany<Upstream>, rhs: Publishers.MergeMany<Upstream>) -> Bool
 }
-
-extension Publishers.Zip : Equatable where A : Equatable, B : Equatable {
-
-    /// Returns a Boolean value that indicates whether two publishers are equivalent.
-    ///
-    /// - Parameters:
-    ///   - lhs: A zip publisher to compare for equality.
-    ///   - rhs: Another zip publisher to compare for equality.
-    /// - Returns: `true` if the corresponding upstream publishers of each zip publisher are equal, `false` otherwise.
-    public static func == (lhs: Publishers.Zip<A, B>, rhs: Publishers.Zip<A, B>) -> Bool
-}
-
-/// Returns a Boolean value that indicates whether two publishers are equivalent.
-///
-/// - Parameters:
-///   - lhs: A zip publisher to compare for equality.
-///   - rhs: Another zip publisher to compare for equality.
-/// - Returns: `true` if the corresponding upstream publishers of each zip publisher are equal, `false` otherwise.
-extension Publishers.Zip3 : Equatable where A : Equatable, B : Equatable, C : Equatable {
-
-    /// Returns a Boolean value indicating whether two values are equal.
-    ///
-    /// Equality is the inverse of inequality. For any values `a` and `b`,
-    /// `a == b` implies that `a != b` is `false`.
-    ///
-    /// - Parameters:
-    ///   - lhs: A value to compare.
-    ///   - rhs: Another value to compare.
-    public static func == (lhs: Publishers.Zip3<A, B, C>, rhs: Publishers.Zip3<A, B, C>) -> Bool
-}
-
-/// Returns a Boolean value that indicates whether two publishers are equivalent.
-///
-/// - Parameters:
-///   - lhs: A zip publisher to compare for equality.
-///   - rhs: Another zip publisher to compare for equality.
-/// - Returns: `true` if the corresponding upstream publishers of each zip publisher are equal, `false` otherwise.
-extension Publishers.Zip4 : Equatable where A : Equatable, B : Equatable, C : Equatable, D : Equatable {
-
-    /// Returns a Boolean value indicating whether two values are equal.
-    ///
-    /// Equality is the inverse of inequality. For any values `a` and `b`,
-    /// `a == b` implies that `a != b` is `false`.
-    ///
-    /// - Parameters:
-    ///   - lhs: A value to compare.
-    ///   - rhs: Another value to compare.
-    public static func == (lhs: Publishers.Zip4<A, B, C, D>, rhs: Publishers.Zip4<A, B, C, D>) -> Bool
-}

Sources/OpenCombine/Helpers/Violations.swift

@@ -30,4 +30,10 @@ extension Subscribers.Demand {
         precondition(rawValue <= Subscribers.Demand.unlimited.rawValue)
         precondition(rawValue > Subscribers.Demand.none.rawValue)
     }
+
+    @_transparent
+    @inline(__always)
+    internal func assertValid() {
+        precondition(rawValue <= Subscribers.Demand.unlimited.rawValue)
+    }
 }