use UnsafeBufferPointer instead of Array

Sources/Runtime/Metadata/FuntionMetadata.swift

@@ -36,10 +36,10 @@ struct FunctionMetadata: MetadataType {
 
     private func argumentInfo() -> (Int, [Any.Type], Any.Type) {
         let n = numberArguments()
-        var argTypes = pointer.pointee.argumentVector.vector(n: n + 1)
+        let argTypeBuffer = pointer.pointee.argumentVector.vector(n: n + 1)
 
-        let resultType = argTypes[0]
-        argTypes.removeFirst()
+        let resultType = argTypeBuffer[0]
+        let argTypes = Array(argTypeBuffer.dropFirst())
 
         return (n, argTypes, resultType)
     }

Sources/Runtime/Metadata/TupleMetadata.swift

@@ -36,10 +36,8 @@ struct TupleMetadata: MetadataType, TypeInfoConvertible {
         return labels
     }
 
-    func elements() -> [TupleElementLayout] {
-        let n = numberOfElements()
-        guard n > 0 else { return [] }
-        return pointer.pointee.elementVector.vector(n: n)
+    func elements() -> UnsafeBufferPointer<TupleElementLayout> {
+        return pointer.pointee.elementVector.vector(n: numberOfElements())
     }
 
     func properies() -> [PropertyInfo] {

Sources/Runtime/Pointers/RelativeVectorPointer.swift

@@ -24,10 +24,10 @@ import Foundation
 
 struct RelativeVectorPointer<Offset: FixedWidthInteger, Pointee> {
     var offset: Offset
-    mutating func vector(metadata: UnsafePointer<Int>, n: Int) -> [Pointee] {
+    mutating func vector(metadata: UnsafePointer<Int>, n: Int) -> UnsafeBufferPointer<Pointee> {
         return metadata.advanced(by: numericCast(offset))
             .raw.assumingMemoryBound(to: Pointee.self)
-            .vector(n: n)
+            .buffer(n: n)
     }
 }
 

Sources/Runtime/Pointers/Vector.swift

@@ -26,10 +26,10 @@ struct Vector<Element> {
 
     var element: Element
 
-    mutating func vector(n: Int) -> [Element] {
+    mutating func vector(n: Int) -> UnsafeBufferPointer<Element> {
         return withUnsafePointer(to: &self) {
             $0.withMemoryRebound(to: Element.self, capacity: 1) { start in
-                return start.vector(n: n)
+                return start.buffer(n: n)
             }
         }
     }

Sources/Runtime/Utilities/Pointer+Extensions.swift

@@ -32,12 +32,8 @@ extension UnsafePointer {
         return UnsafeMutablePointer<Pointee>(mutating: self)
     }
 
-    func vector(n: Int) -> [Pointee] {
-        var result = [Pointee]()
-        for i in 0..<n {
-            result.append(advanced(by: i).pointee)
-        }
-        return result
+    func buffer(n: Int) -> UnsafeBufferPointer<Pointee> {
+        return UnsafeBufferPointer(start: self, count: n)
     }
 }
 
@@ -57,12 +53,8 @@ extension UnsafeMutablePointer {
         return UnsafeMutableRawPointer(self)
     }
 
-    func vector(n: Int) -> [Pointee] {
-        var result = [Pointee]()
-        for i in 0..<n {
-            result.append(advanced(by: i).pointee)
-        }
-        return result
+    func buffer(n: Int) -> UnsafeMutableBufferPointer<Pointee> {
+        return UnsafeMutableBufferPointer(start: self, count: n)
     }
 
     func advanced(by n: Int, wordSize: Int) -> UnsafeMutableRawPointer {