Restrict ScopedInstruction to SingleValueInstruction

Author: atrick

SwiftCompilerSources/Sources/SIL/Instruction.swift

@@ -865,7 +865,7 @@ final public class BeginAccessInst : SingleValueInstruction, UnaryInstruction {
 // An instruction that is always paired with a scope ending instruction
 // such as `begin_access` (ending with `end_access`) and `alloc_stack`
 // (ending with `dealloc_stack`).
-public protocol ScopedInstruction {
+public protocol ScopedInstruction: SingleValueInstruction {
   // The type of the ending instructions (while `IteratorProtocol` would be
   // ideal, for performance reasons we allow the user to specify any type as return)
   associatedtype EndInstructions