Make SkNoncopyable movable

SkNoncopyable declares (but does not define) its copy constructor and
copy assignment operator. These are also private so the error for misuse
happens at compile-time instead of link-time.

However, this seems to be from before C++11.

Because other constructors were declared, the compiler does not generate
a move constructor or a move assignment operator. The result of this is
perfectly legal non-copying scenarios are also accidentally blocked. An
example of this is returning the non-copyable type. The object being
returned is a candidate for a move, since it is about to be destroyed.
And in C++17 copy elision is actually guaranteed.

Change-Id: Ia31be9091c644f31a45dd18216330a68be3cf456
Reviewed-on: https://skia-review.googlesource.com/14294
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/include/core/SkTypes.h b/include/core/SkTypes.h
index beb2be5143..1dd672bea4 100644
--- a/include/core/SkTypes.h
+++ b/include/core/SkTypes.h
@@ -442,11 +442,13 @@ be copied. It hides its copy-constructor and its assignment-operator.
 */
 class SK_API SkNoncopyable {
 public:
-    SkNoncopyable() {}
+    SkNoncopyable() = default;
 
-private:
-    SkNoncopyable(const SkNoncopyable&);
-    SkNoncopyable& operator=(const SkNoncopyable&);
+    SkNoncopyable(SkNoncopyable&&) = default;
+    SkNoncopyable& operator =(SkNoncopyable&&) = default;
+
+    SkNoncopyable(const SkNoncopyable&) = delete;
+    SkNoncopyable& operator=(const SkNoncopyable&) = delete;
 };
 
 #endif /* C++ */