Add two test cases that regressed after a previous attempt at fixing a bug

Author: slavapestov

test/decl/protocol/req/associated_type_inference_foundation_1.swift

@@ -0,0 +1,33 @@
+// RUN: %target-typecheck-verify-swift -enable-experimental-associated-type-inference
+// RUN: %target-typecheck-verify-swift -disable-experimental-associated-type-inference
+
+// REQUIRES: objc_interop
+
+import Foundation
+
+public struct CustomCollection<T>: RandomAccessCollection {
+    public typealias Indices = Range<Int>
+    
+    public var startIndex: Int { fatalError() }
+    public var endIndex: Int { fatalError() }
+    public var count: Int { fatalError() }
+    
+    public subscript(position: Int) -> T {
+        get { fatalError() }
+        set { fatalError() }
+    }
+    
+    public var underestimatedCount: Int { fatalError() }
+}
+
+extension CustomCollection: ContiguousBytes where Element == UInt8 {
+    public func withUnsafeBytes<R>(_ body: (UnsafeRawBufferPointer) throws -> R) rethrows -> R {
+        fatalError()
+    }
+}
+
+extension CustomCollection: DataProtocol where Element == UInt8 {
+    public var regions: CollectionOfOne<CustomCollection<UInt8>> {
+        fatalError()
+    }
+}

test/decl/protocol/req/associated_type_inference_foundation_2.swift

@@ -0,0 +1,45 @@
+// RUN: %target-typecheck-verify-swift -enable-experimental-associated-type-inference
+// RUN: %target-typecheck-verify-swift -disable-experimental-associated-type-inference
+
+// REQUIRES: objc_interop
+
+import Foundation
+
+public struct CustomCollection<Element>: RandomAccessCollection, MutableCollection, ExpressibleByArrayLiteral {
+    public typealias Indices = Range<Int>
+    public typealias Index = Int
+
+    public init() {}
+
+    public init(arrayLiteral elements: Element ...) {
+        fatalError()
+    }
+}
+
+extension CustomCollection {
+    public var startIndex: Int { fatalError() }
+    public var endIndex: Int { fatalError() }
+
+    public subscript(position: Int) -> Element {
+        get { fatalError() }
+        set { fatalError() }
+    }
+}
+
+extension CustomCollection: RangeReplaceableCollection {
+    public mutating func append(_ newElement: Element) { }
+    public mutating func append<S: Sequence>(contentsOf newElements: S) where S.Element == Element { }
+    public mutating func reserveCapacity(_ minimumCapacity: Int) { }
+    public mutating func removeAll(keepingCapacity keepCapacity: Bool = false) { }
+    public mutating func replaceSubrange<C: Collection>(_ subRange: Range<Int>, with newElements: C) where C.Element == Element { }
+}
+
+extension CustomCollection {
+    public func withUnsafeBytes<R>(_ body: (UnsafeRawBufferPointer) throws -> R) rethrows -> R { fatalError() }
+}
+
+extension CustomCollection: ContiguousBytes where Element == UInt8 { }
+
+extension CustomCollection: DataProtocol where Element == UInt8 {
+    public var regions: CollectionOfOne<CustomCollection<UInt8>> { fatalError() }
+}