Support: Use std::unique_ptr for SignpostEmitter::Impl, NFC

[dexonsmith]

Summary

Replace some manual memory management with std::unique_ptr.

[dsanders]

LGTM

[dexonsmith]

Apparently some hosts don't like using std::unique_ptr for types that only have forward declarations. Reverted in 078072285d3fbdaa94f9a91140eb5c1223b548af and left a comment.

llvm/include/llvm/Support/Signposts.h

 /// of Interest track on the instruments timeline.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_SUPPORT_SIGNPOSTS_H
 #define LLVM_SUPPORT_SIGNPOSTS_H
 
 #include "llvm/ADT/StringRef.h"
+#include <memory>
 
 namespace llvm {
 class SignpostEmitterImpl;
 
 /// Manages the emission of signposts into the recording method supported by
 /// the OS.
 class SignpostEmitter {
-  SignpostEmitterImpl *Impl;
+  std::unique_ptr<SignpostEmitterImpl> Impl;
 
 public:
   SignpostEmitter();
   ~SignpostEmitter();
 
   bool isEnabled() const;
 
   /// Begin a signposted interval for a given object.
   void startInterval(const void *O, StringRef Name);
   /// End a signposted interval for a given object.
   void endInterval(const void *O, StringRef Name);
 };
 
 } // end namespace llvm
 
 #endif // LLVM_SUPPORT_SIGNPOSTS_H

llvm/lib/Support/Signposts.cpp

 #if LLVM_SUPPORT_XCODE_SIGNPOSTS
 #define HAVE_ANY_SIGNPOST_IMPL 1
 #else
 #define HAVE_ANY_SIGNPOST_IMPL 0
 #endif
 
 SignpostEmitter::SignpostEmitter() {
 #if HAVE_ANY_SIGNPOST_IMPL
-  Impl = new SignpostEmitterImpl();
-#else  // if HAVE_ANY_SIGNPOST_IMPL
-  Impl = nullptr;
+  Impl = std::make_unique<SignpostEmitterImpl>();
 #endif // if !HAVE_ANY_SIGNPOST_IMPL
 }
 
-SignpostEmitter::~SignpostEmitter() {
-#if HAVE_ANY_SIGNPOST_IMPL
-  delete Impl;
-#endif // if HAVE_ANY_SIGNPOST_IMPL
-}
+SignpostEmitter::~SignpostEmitter() = default;
 
 bool SignpostEmitter::isEnabled() const {
 #if HAVE_ANY_SIGNPOST_IMPL
   return Impl->isEnabled();
 #else
   return false;
 #endif // if !HAVE_ANY_SIGNPOST_IMPL
 }