Revert "Merge pull request swiftlang#82284 from glessard/rdar153219174-UMBP-mutableSpan-62"

This reverts commit 845b68a, reversing
changes made to 3d1c592.

Author: glessard

stdlib/public/core/UnsafeBufferPointer.swift.gyb

@@ -583,18 +583,6 @@ extension Unsafe${Mutable}BufferPointer where Element: ~Copyable {
       return unsafe _overrideLifetime(span, borrowing: self)
     }
   }
-%if Mutable:
-
-  @unsafe
-  @available(SwiftStdlib 6.2, *)
-  public var mutableSpan: MutableSpan<Element> {
-    @lifetime(borrow self)
-    @_alwaysEmitIntoClient
-    get {
-      unsafe MutableSpan(_unsafeElements: self)
-    }
-  }
-%end
 }
 
 extension Unsafe${Mutable}BufferPointer {

stdlib/public/core/UnsafeRawBufferPointer.swift.gyb

@@ -1162,16 +1162,6 @@ extension Unsafe${Mutable}RawBufferPointer {
     }
   }
 
-  @unsafe
-  @available(SwiftStdlib 6.2, *)
-  public var mutableBytes: MutableRawSpan {
-    @lifetime(borrow self)
-    @_alwaysEmitIntoClient
-    get {
-      unsafe MutableRawSpan(_unsafeBytes: self)
-    }
-  }
-
 %  end
   @_alwaysEmitIntoClient
   public func withContiguousStorageIfAvailable<R>(

test/abi/macOS/arm64/stdlib.swift

@@ -933,8 +933,6 @@ Added: _$ss10ArraySliceV11mutableSpans07MutableD0VyxGvr
 Added: _$ss15ContiguousArrayV11mutableSpans07MutableD0VyxGvr
 Added: _$ss11InlineArrayVsRi__rlE11mutableSpans07MutableD0Vyq_Gvr
 Added: _$ss15CollectionOfOneV11mutableSpans07MutableE0VyxGvr
-Added: _$sSrsRi_zrlE11mutableSpans07MutableB0VyxGvr
-Added: _$sSw12mutableBytess14MutableRawSpanVvr
 
 // _SwiftifyInfo enum for _SwiftifyImports macro
 Added: _$ss13_SwiftifyExprO5paramyABSicABmFWC

test/abi/macOS/x86_64/stdlib.swift

@@ -934,8 +934,6 @@ Added: _$ss10ArraySliceV11mutableSpans07MutableD0VyxGvr
 Added: _$ss15ContiguousArrayV11mutableSpans07MutableD0VyxGvr
 Added: _$ss11InlineArrayVsRi__rlE11mutableSpans07MutableD0Vyq_Gvr
 Added: _$ss15CollectionOfOneV11mutableSpans07MutableE0VyxGvr
-Added: _$sSrsRi_zrlE11mutableSpans07MutableB0VyxGvr
-Added: _$sSw12mutableBytess14MutableRawSpanVvr
 
 // _SwiftifyInfo enum for _SwiftifyImports macro
 Added: _$ss13_SwiftifyExprO5paramyABSicABmFWC

test/stdlib/Span/MutableRawSpanTests.swift

@@ -514,26 +514,3 @@ suite.test("extracting suffixes")
     expectEqual(span.extracting(droppingFirst: 1).byteCount, b.count)
   }
 }
-
-suite.test("MutableRawSpan from UnsafeMutableRawBufferPointer")
-.require(.stdlib_6_2).code {
-  guard #available(SwiftStdlib 6.2, *) else { return }
-
-  let capacity = 4
-  let b = UnsafeMutableRawBufferPointer.allocate(
-    byteCount: capacity*MemoryLayout<Int64>.stride,
-    alignment: MemoryLayout<Int64>.alignment
-  )
-  defer {
-    b.deallocate()
-  }
-  _ = b.initializeMemory(as: Int64.self, fromContentsOf: 0..<Int64(capacity))
-
-  var span = b.mutableBytes
-  span.storeBytes(of: 3, toByteOffset: 10, as: UInt16.self)
-
-  _ = consume span
-
-  let v = b.load(fromByteOffset: 8, as: Int64.self)
-  expectNotEqual(v, 1)
-}

test/stdlib/Span/MutableSpanTests.swift

@@ -720,25 +720,3 @@ suite.test("extracting suffixes")
     expectEqual(span.extracting(droppingFirst: 1).count, b.count)
   }
 }
-
-suite.test("MutableSpan from UnsafeMutableBufferPointer")
-.require(.stdlib_6_2).code {
-  guard #available(SwiftStdlib 6.2, *) else { return }
-
-  let capacity = 4
-  let b = UnsafeMutableBufferPointer<Int>.allocate(capacity: capacity)
-  defer {
-    b.deallocate()
-  }
-  _ = b.initialize(fromContentsOf: 0..<capacity)
-
-  var span = b.mutableSpan
-  expectEqual(span.count, capacity)
-
-  span.swapAt(0, 3)
-  span.swapAt(1, 2)
-
-  _ = consume span
-
-  expectTrue(b.elementsEqual((0..<capacity).reversed()))
-}